Research ArticleEssential Oil Extracted from Cymbopogon citronella Leaves bySupercritical Carbon Dioxide Antioxidant andAntimicrobial Activities

Hong Wu123 Jilie Li 1 Yuan Jia1 Zhihong Xiao23 Peiwang Li23 Yixian Xie1

Aihua Zhang123 Rukuan Liu23 Zewen Ren1 Mengrui Zhao1 Chaozhen Zeng1

and Changzhu Li 23

1Key Laboratory of Cultivation and Protection Co-constructed for Non-wood Forest Trees Ministry of EducationCentral South University of Forestry and Technology Changsha 410004 China2Key Laboratory of State Forestry Administration on Utilization Science for Southern Woody Oil ResourceHunan Academy of Forestry Changsha 410004 China3Hunan Engineering and Technology Research Center of Lipids Changsha 410004 China

Correspondence should be addressed to Jilie Li lijilie12163com and Changzhu Lilichangzhu2013aliyuncom

Received 15 June 2018 Accepted 28 October 2018 Published 2 January 2019

Academic Editor Jesus Simal-Gandara

Copyright copy 2019 Hong Wu et al is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

To improve essential oil quality especially to reserve the thermal instability of compounds supercritical CO2 extraction (SFE) wasapplied to recover essential oil from Cymbopogon citronella leaves A response surface methodology was applied to optimize theextraction processe highest essential oil yield was predicted at extraction time 120 min extraction pressure 25 MPa extractiontemperature 35degC and CO2 flow 18 Lh for the SFE processing Under these experimental conditions the mean essential oil yieldis 440 In addition the chemical compositions of SFE were compared with those obtained by hydrodistillation extraction (HD)ere were 41 compounds obtained of SFE while 35 compounds of HD Alcohols and aldehydes were the main compositions inthe essential oils Furthermore the antioxidant activities and antimicrobial of essential oils obtained by HD and the evaluatedcondition of SFE were compared Results showed that the antioxidant activities of SFE oil are better than those of HD Minimuminhibitory concentrations (MICs) were determined by the microdilution method Essential oil obtained from SFE and HDexhibited a significant antimicrobial activity against all tested microorganisms It is confirmed that the SFE method can be analternative processing method to extract essential oils from Cymbopogon citronella leaves

1 Introduction

Cymbopogon citronella Stapf (C citronella) also known aslemongrass belongs to Cymbopogon Spreng familyC citronella is a perennial grass that is widely cultivated intropic and subtropic regions of the eastern hemisphere suchas China [1 2] C citronella is barren and drought resistantand can tolerate a temperature range from minus25degC to 40degCsuggesting that it can be planted in a wide range of envi-ronmental conditions [3] e essential oil of C citronellahas been studied widely Sriramavaratharajan et al [3] has

found that the essential oil was mainly distributed in the Ccitronella leaves In other research studies the componentsof the C citronella essential oil were identified includingmainly citral (aldehydes geranial + neral) and terpenes(myrcene-monoterpene and geranial-terpenic alcohol)[1 2] As an economic oil crop the fragrance odour togetherwith the various pharmacological activities promote theessential oil widely used as a flavor enhancer in food per-fumery soap cosmetic pharmaceutical insecticide in-dustries etc [4 5] For example the citral from the essentialoil could be used as a raw material to prepare vitamins (A E

HindawiJournal of Analytical Methods in ChemistryVolume 2019 Article ID 8192439 10 pageshttpsdoiorg10115520198192439

and K) ionone methylionone and perfumes [1 6] Con-sequently this essential oil-producing crop has attractedhuge economic interests in China and abroad in recent years

However the C citronella essential oil has always beenobtained by hydrodistillation extraction (HD) methodActually the HD is a widely used method to measure theyield of thermally stable essential oil even today Variousresearchers have extracted the essential oil from different oilcrops with HD [1 2] Other studies [1 2] extracted theessential oil (of 003 feedstock) from Artemisia capillarisT by HD Huang [7] extracted 025 and 175 of theessential oil from Cinnamomum cassia P and Zingiberofficinale R by the HD 269 of essential oil was extractedfrom C citronella by the HD with the response surfacemethod (RSM) reported in [1 2] In addition Sargenti andLanccedilas [2] performed and reviewed the relative analysis forextraction efficiently of essential oil with various methodsindicating HD can be widely used as a common processingfor most thermally stable essential oils However manyresearch studies had reported that the high temperature andlong treatment time in extraction processing contributed todegradation of thermosensitive compounds and need a greatamount of energy consumption [8] us it is necessary tocontinue to search and establish possible alternative processto further improve essential oil quality Furthermore inconsidering the subsequent separation of the essential oil inextraction processing our group proposed the method ofsupercritical fluid extraction (SFE) in this study

As a newly and environmentally separating technologySFE also referred to as pressurized extraction employsenvironmental-friendly agents such as CO2 and water asthe mediator SFE is an effective and selective sample sep-aration technique which has been widely used in industrialproduction environmental analysis and analytical chem-istry [9 10] Several studies have demonstrated that the SFEprocess was applied in extracting bioactive compounds suchas flavonoids active polysaccharide protein polyphenoland essential oil [9] Compared with various other extractionmethods Pavela [1] and SargentiLanccedilas [2] found that theSFE was efficient in selectively fractionating the essential oilunder mild extraction conditions ey also evaluated theeffect of different factors on extraction yield of essential oilby SFE resulting in 151 of essential oil [1 2] To ourknowledge nevertheless there was no report in the literatureon using SFE in extraction of essential oil from C citronella

In addition antioxidant and antimicrobial chemistryare interesting topics at present because they play a pivotalrole in pathogenesis of cardiovascular diseases neural dis-orders cancer and aging [11] Consequently a majority ofthe reports also have focused on biological characteristicsand compositions of essential oil extracted from variousother plants [4 8 11 12] such as Rosmarinus officinalisA capillaris and Z officinale but there was few informationabout the essential oil of C citronella leaves essential oil inthe literature

e objective of this study was therefore to optimize theSFE conditions so as to obtain the highest essential oil yieldfrom C citronella leaves In this study the supercriticalcarbon dioxide was employed to extract the essential oil and

the operational parameters were optimized using responsesurface methodology e chemical compositions of theessential oil obtained from C citronella leaves were alsoidentified by gas chromatography mass spectrometry (GC-MS) analysis Furthermore the antioxidant activities andantimicrobial activities of the essential oil extracted by SFEwere compared with those obtained by HD

2 Materials and Methods

21Materials Fresh C citronella leaves were collected froma local farm in Changsha Hunan soon after harvesting andthen transported and preserved in our laboratory e leaveswere air-dried (6 of moisture) and milled into powdersusing a frozen broken molecular machine (SPEX Sample-Prep USA) Powders were screened through an 80-meshsieve and kept in a refrigerator at 4degC until further use

22 Hydrodistillation (HD) Process 100 g of dried milledpowder was immersed in 300mL water and distilled for 3 husing a Clevenger-type apparatus which was found to besufficient for completing the extraction process e es-sential oil was collected and was then weighed e collectedoil was dried with a small amount of anhydrous sodiumsulfate and refrigerated prior to further analysis

23 Supercritical Fluid Extraction (SFE) Process e ex-traction processing was conducted in a 500mL extractionvessel (Hunan Supercritical Extraction Company LtdJiangsu province) e extraction was according to S RSargenti [2] with minor modification Briefly a 200 g driedsubstance would be placed in an extraction kettle includingextractor and separator would be heated to 30degC and 25degCrespectively CO2 is cooled in a condenser and filled into theextractor e pressurization was conducted to maintain thepressure at 20 MPa by filling the CO2 thereafter the flow ofCO2 was adjusted to 20 Lh for essential oil by circulatoryextraction After extraction the separation temperature andpressure were controlled to 25degC and 4MPa respectively Toevaluate the effect of the variables on the extraction yield ofessential oil those factors including the extraction timeextraction temperature and CO2 flow were studied re-spectively with single-factor experimental e standarddeviation is less than 40

24 Optimization of SFE Based on the single-factor studythe optimized experimental conditions for maximum ex-traction of essential oil from C citronella leaves using su-percritical CO2 were determined using the design-expertV806 Given the influence of the above variables the ex-traction processing of essential oil was optimized with aBoxndashBehnken design (BBD) and response surface meth-odology (RSM) [13] For the BBD experiments of 4 factorsthere were 24 experiments augmented and 3 replications atthe center values (zero level) e levels of each factor andthe design table are given in Tables 1 and 2

2 Journal of Analytical Methods in Chemistry

Design-expert V806 was used for the experiment de-signs and subsequent regression analysis of the responsedata Statistical analysis of the model was performed toevaluate the analysis of variance (ANOVA) e quality ofthe polynomial model equation was judged statistically usingthe coefficient of determination R2 and adjustment R2 andits statistical significance was determined by the F value andP value e significance of the regression coefficients wastested by some parameters such as coefficient of variation(CV) and adequate precision

25 GC-MS Analysis e compositions of essential oilobtained by HD and SFE (in evaluated condition) wereanalyzed by a GC-MS analysis e examination was per-formed on a Scion SQ (Bruker USA) equipped with an 8400autosampler Samples were injected into the capillary col-umn in the split and splitless modes A 1 μL aliquot of testsolution was injected into a DB-5 (30m times 250 μm times 025 μmAgilent USA) e oven temperature was programmed at

5degCmin from 40degC (hold 2min) to 100degC (hold 2min) andthen 10degCmin to 250degC (hold 2min) e injector tem-perature was set at 230degC in the split and splitless modeseflow rate of the carrier gas helium was set at 1mLmin thetransmission line temperature was set at 200degC and the ionsource temperature was set at 250degC e electron ionization(EI) source operated at minus70 eV e MS spectra weremonitored in the full scan mode from 15 to 500mz with ascan event time of 03 s and a scan speed of 2000 μs esolvent delay time was set to 600min MS data analyzed byGCMS were processed by Analyzer Pro Software (Spec-tralworks Ltd Runcorn UK) including deconvolution ofmass spectra data collection alignment and normalizationMetabolite peaks were deconvoluted and collected using anarea threshold of 7000 height threshold of 1 signal to noiseratio of 3 width threshold of 001 scan windows of 5 andsmoothing of 5 e data were aligned with a retention timewindow of 03min

26 Assay of Antioxidant Activities

261 DPPH Assay e free-radical scavenging activity ofessential oil from C citronella leaves was measured by 11-diphenyl-2-picryl-hydrazyl (DPPH) assay according to themethod of [13] Ascorbic acid (AA) and 26-di-tert-butyl-4-methylphenol (BHT) were used as positive control

262 Self-Oxidation Assay e scavenging ability of 123-phentriol to self-oxidize was investigated according to themethod with a minor modification [14] AA and BHT wereused as positive control

27 Assay of Antimicrobial Activities

271 Twofold Dilution Assay Two bacterial strains and twofungal strains were used in this study Staphylococcus aureusE coli Aspergillus niger and Aspergillus fumigatus Allstrains were gained from Key Laboratory of Academy of LifeSciences in Central South University of Forestry andTechnology Hunan China e bacterial cultures weregrown in the liquid medium at a suitable temperature ebacterial strains were incubated on micrococcus nutrientand YM media and then cultured with shaking for 12 h at37degC or 30degC Two plant extracts which were respectivelycollected within SFE and HD process were screened forantimicrobial activity using a serial twofold dilution assay[15 16] e minimum inhibitory concentration (MIC) ofeach compound was defined as the lowest concentration thatinhibited microorganism growth Bacterial growth wasevaluated visually based on the degree of turbidity Citral wasused as positive control

272 Paper Disc Diffusion Assay e antimicrobial activ-ities of the plant extracts and fractions were determined bypaper disc diffusion assay [15 17 18] e diameter of eachinhibitory zone was measured (in mm) Negative controls

Table 2 Full factorial BBD matrix of three variables in coded unitsand the experimentally observed response

Runs X1 X2 X3 X4 Extraction yield ()1 110 22 35 18 4292 110 28 35 18 4213 130 22 35 18 4234 130 28 35 18 4325 120 25 32 16 4066 120 25 32 20 3917 120 25 38 16 3898 120 25 38 20 3929 110 25 35 16 42610 110 25 35 20 41111 130 25 35 16 41912 130 25 35 20 41513 120 22 32 18 40714 120 22 38 18 39415 120 28 32 18 40616 120 28 38 18 39817 110 25 32 18 39518 110 25 38 18 40219 130 25 32 18 40820 130 25 38 18 40421 120 22 35 16 42622 120 22 35 20 41123 120 28 35 16 41924 120 28 35 20 42225 120 25 35 18 43726 120 25 35 18 43627 120 25 35 18 435

Table 1 Experimental range and levels of independent variables

Variables SymbolCode levelsminus1 0 1

Extraction time (min) X1 110 120 130Extraction pressure (MPa) X2 22 25 28Extraction temperature (degC) X3 32 35 38CO2 flow (Lh) X4 16 18 20

Journal of Analytical Methods in Chemistry 3

were prepared using the same solvents employed to dissolvethe plant extracts Citral was used as positive control

28 Analytical Procedures All samples were prepared andanalyzed in triplicate All figures were obtained by using oneof Origin 85 Microsoft 2010 Design-Expert 806 andonimic 90 To verify the statistical significance of all pa-rameters the values of mean plusmn SD were calculated e yieldof essential oil obtained by HD and SFE were determined bygravimetric analysis e extraction yield () of essential oilwas calculated as follows

Y1() 100 times ρ times V1 (1)

where Y1 is the extraction yield () ρ is the destiny of theessential oil andV1 is the volume of the essential oil ecapability of scavenging the DPPH radical was calculatedusing the following equation

I() 1minus Ai minusAj1113872 1113873

Ac

⎡⎣ ⎤⎦ times 100 (2)

where Ac is the absorbance of the bland Ai is the absorbanceof the sample reacted with the DPPH and Aj is the ab-sorbance of the sample e scavenging ability of 123-phentriol of essential oil to self-oxidize was calculated usingthe following equation

Y2() 1minus S1

S21113888 1113889 times 100 (3)

where Y2 is the scavenging ability S1 is the slope of thesample and S2 is the slope of control

3 Results and Discussion

31 Determining Levels for Independent Variables In recentreports many researchers have indicated the efficiency ofextraction would be impacted significantly by some factorsin SFE processing such as extraction time extractiontemperature and CO2 flow which were respectively studiedto evaluate the impact of parameters on the SFE the resultsare shown in Figure 1 Firstly the effect of different ex-traction time periods on the extraction essential oil yield wasexamined at 30 60 90 120 and 150min in the process ofSFE e essential oil produced during SFE with respect toextraction time on extraction yield is shown in Figure 1(a)Results in the extraction yield of essential oil was increasedwith the extraction time going up from 30min to 150minWhen the extraction time was shorter than 60min the oilwas extracted significantly from the C citronella but theyield was still at a lower level At 120min the extraction yieldof essential oil reached 40 (ww on origin feedstock)ereafter the extraction yield was almost stabilizing withthe extension of time which would increase the cost of SFEtreatment erefore it is favorable to choose the range of110ndash130min as a desirable holding time for the SFE ofessential oil

Extraction temperature was one of the factors affectingextraction effectiveness According to the above results

the influence of extraction temperature at 20 25 30 35 and40degC was studied (Figure 1(b)) As seen in Figure 1(b) theextraction yield of C citronella essential oil reduced sig-nificantly with the extraction temperature going up from20degC to 40degCus there are obviously a large number of theessential oils extracted during the SFE from 26 to 40e reason maybe the viscosity of supercritical fluid de-creased and the diffusion coefficient of fluid increased withthe elevation of extraction temperature meanwhile theBrownian motion of essential oil in C citronella was en-hanced so that accelerated the processing of mass transferresulting in improving the dissolubility of oil [2] At 35degC forexample the extraction yield of essential oil increased to42 (ww in original feedstock) approximately Howeverno obvious variation in extraction yield was shown after35degC In addition the constituent and structure of essentialoil would be degraded and destructed according to somereports [8] Considering the economical and extractionefficiency 32degCndash38degC was chosen as a desirable holdingtemperature during SFE process

e influence of CO2 flow of 8 12 14 18 and 22 Lh isshown in Figure 1(c) which indicated that the flow of CO2was a notable factor influencing the extraction results Whenthe CO2 flow increased from 8 Lh to 16 Lh the extractionyield of essential oil increased sharply achieving from 24to 36 With the increasing flow of CO2 nevertheless therewas an abnormal decrease in extraction yield of essential oilSome researchers indicated that it would be conducive to thearea of effective contact between feedstock and CO2 at thelower velocity condition so that it could be much easier toextract the essential oil from original [19] Besides when theflowing of CO2 was too higher it would possibly lead to theinadequacy for the area of contact but also part of extractedoil could be brought back to the extractor from the separatorin which the mixture was not separated thoroughly for theshorter separation time It was thus of interest to obtainessential oil within limits of CO2 flow

e effects of extraction pressure on the extraction yieldof essential oil were studied with five levels at intervals of5MPa from 10 to 30MPa As illustrated in Figure 1(d) withan increase in the extraction pressure from 10 to 25MPa theyield of essential oil was significantly increased (from 27 to40) As the extraction pressure rose from 25 to 30MPa theextraction yield of essential oil changed little (sim4)is wasprobably according to the supercritical extraction principlereported by some researchers [2 7 19 20] due to theenhancement in density and diffusivity of supercritical fluidwith the increasing extraction pressure which prompted theimprovement of the strength of extraction However it wasfound that higher extraction pressure decreased the masstransfer time even carrying part of extracted essential oil in aseparator Consequently the extraction yield would bestabilized within higher extraction pressure In consider-ation of cost within the range of 22ndash28MPa was the ap-propriate extraction pressure during SFE processing in thisstudy

By comparison some recent studies had reported thatvarious factors existed in the separation reactor would havehad an influence on the yield of active substance extracted

4 Journal of Analytical Methods in Chemistry

from biomass during SFE processing [21] Accordingly somekey factors such as separation pressure and separationtemperature were evaluated for the SFE treatment in thispart As shown in Figures 1(e) and 1(f) the effect of sepa-ration pressure and separation temperature was investigatedfrom 25MPa to 45MPa and 20degC to 40degC respectively It wasabnormally apparent that the separation pressure and sepa-ration temperature resulted in an insignificant impact onextraction yield wandering in 35 approximately e resultwas beyond the expectation and inconsistent with previousresults that the subsequent separation process would play arestrictive role on extracting essential oil indicating the su-percritical CO2 had an outstanding capability of efficientextraction of essential oil with SFE which was not affected byseparation pressure and separation temperature Conse-quently in consideration of cost 3MPa and 25degC (at roomtemperature) were selected to be the separation pressure andseparation temperature in the next experiment

32 Construction of the SFE Processing After the single-factor study about the evaluation of the impact of variousparameters on the SFE treatment as shown in Figure 1 theresults had revealed the various components that changedtendency in the material including extraction time ex-traction temperature CO2 flow extraction pressure sepa-ration pressure and separation temperature respectivelyereinto the separation pressure and separation temper-ature were not considered in this experiment Although alarge number of essential oils had been extracted fromC citronella in the SFE treatment the high efficiency needs

severe treatment conditions that would increase the cost ofSFE treatment In addition it would be also increase the costbecause of interaction of various variables Accordinglythese variables were taken into careful consideration byusing BoxndashBehnken design (BBD) with the soft of Design-Expert V806 in this study

e levels of each factor are given in Table 1 Twenty-seven experiments were carried out from the design (Ta-ble 2) e results of the second-order response surfacemodel fitting for extraction yield in the form of analysis ofvariance (ANOVA) are given in Table 3 To test the fit of themodel the regression equation and determination co-efficient R2 were evaluated e model presented a highdetermination coefficient (R2 0976) explaining 976 ofthe variability in the response (Table 3) e coefficients ofregression were calculated and the following regressionequation (4) was obtained

Table 3 presents Fisherrsquos F-test of ANOVA which alsoproves that this regression model was highly statisticallysignificant (Plt 00001) At the same time the relativelylower value of the coefficient of variation (CV 325 lt 10)indicates good precision and reliability of the experimentscarried out Adequate precision for our model has a signal-to-noise ratio of 18571 (gt4) which indicates an adequatesignal e signification of each coefficient was determinedby Tand Pwhich is also listed in Table 3 which demonstratesthat all the linear model terms (X3 and X4) and quadraticmodel term (X1X2 X2X4 and X3X4) were significantMoreover the interactive model terms X1X2 X2X4 andX3X4 were significant (Plt 005) while the interactive modelterms of X1X3 X1X4 and X2X3 were insignificant (Pgt 01)

2020

25

30

35

40Ex

trac

tion

yiel

d (

)

40 60 80 100 120 140 160Extraction time (min)

(a)

25

30

35

40

20 25 30 35 40Extraction temperature (degC)

Extr

actio

n yi

eld

()

(b)

8 12 16 20 24

24

28

32

36

Extr

actio

n yi

eld

()

CO2 flow (Lh)

(c)

Extr

actio

n yi

eld

()

10

40

35

30

2515 20 25 30

Extraction pressure (MPa)

(d)

25 30 35 40 45Separate pressure (MPa)

Extr

actio

n yi

eld

()

354

351

348

345

(e)

20 25 30 35 40Separate temperature (degC)

Extr

actio

n yi

eld

()

356

354

352

350

348

346

(f )

Figure 1 Influence of various parameters on SFE efficiency for essential oil

Journal of Analytical Methods in Chemistry 5

In addition the empirical model (Eq (1)) proved that thepredicted data of the response from the empirical model are inagreement with the observed ones in the range of the op-erating variables On the other hand the value of adjusted(R2 0948) is also very high that indicated a high significanceof the model e maximum extraction yield obtained byusing above selected variables was 436 and the experi-mental maximum obtained was 432 plusmn 006 e data showthat predicted data on the response from empirical modelwere in agreement with those observed in the range of theoperating variables e coefficients of regression were cal-culated and the following regression equation was obtained

Y 437 + 0014167X1 + 0006667X2 minus 0028333X3

minus 0035833X4 minus 005625X21 + 00425X1X2

minus 00275X1X3 + 00275X1X4 minus 00525X22

+ 00125X2X3 + 0045X2X4 minus 02975X23

+ 0045X3X4 minus 012875X24

(4)

where Y response (extraction yield) X1 extraction timeX2 extraction pressure X3 extraction temperature andX4 CO2 flow in coded values

In order to gain a better understanding of the effects ofthe variables on the essential oil of extraction yield from Ccitronella leaves the predicted model was presented as 3D2D response surface graphs as shown in Figure 2 re-spectively which were generated with one variable kept at itsoptimum level and varying the others within the experi-mental range (shown in Table 1) ese variables wereoptimized as follows extraction time 120min extractionpressure 25Mpa extraction temperature 35degC and CO2 flow18 Lh for the SFE process Under optimized condition theextracted essential oil reached 440 Nevertheless the resultis comparable to that reported elsewhere on extraction ofessential oil with various extraction methods indicating thatthe SFE had significantly higher extraction efficiency and

was the most energy-saving method than other methodscombining with an auxiliary instrument that could raise thecost of production [1 5 22ndash24] Consequently these resultshave suggested that the SFE treatment is effective for se-lectively extracting the essential oil from C citronella andmay be expected to use in others active componentsextracted from various plants in future

Recently many researchers argued the extraction yieldand essential oil compositions but paid little attention to theeffect of extraction methods on the essential oil composi-tions It would limit the development and application ofessential oils [5] Accordingly in the next experimentconstitute features of the extracted oil are characterized withmodern analytical equipment

33 Analysis of the Extracted Essential Oil e chemicalcompositions identified in the essential oils extracted by HDand SFE are summarized in Table 4 ere were 35 com-pounds identified in HD essential oils while 41 in SFE es-sential oils ese compositions were grouped into sevenclasses (hydrocarbons alcohols aldehydes esters ketonesalkanes and others) according to their functional groupsAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE e abundant al-cohols can promote the C citronella leaf essential oils usedfor cosmetic applicationse contents of flavourless alkanesin SFE oil were much lower than those of SFE (Table 4)indicating that the essential oil in SFE contains fewer im-purities which were similar to the previous report [8] emain component of essential oil extracted by SFE and HDwas geranialdehyde and the next was geraniol which wereconsistent with previous studies [23 25] Furthermore thecontent of this major compound in SFE extracts was higherthan HDis proved that supercritical fluid did not alter themain effective components in C citronella essential oil butthe content of effective composition and extraction yield ofessential oil was higher [8]

Table 3 ANOVA results for the quadratic equation for the extraction yield of essential oil

Term Freedom degrees Sum of squares Mean square F value Pr gt FModel 14 0564475 004032 3508174 lt00001X1 1 0002408 0002408 2095468 0173353X2 1 0000533 0000533 0464048 0508671X3 1 0009633 0009633 8381873 0013447X4 1 0015408 0015408 1340665 0003257X1 middot X1 1 0016875 0016875 1468278 0002388X1 middotX2 1 0007225 0007225 6286405 0027545X1 middotX3 1 0003025 0003025 2632024 0130689X1 middotX4 1 0003025 0003025 2632024 0130689X2 middotX2 1 00147 00147 1279033 0003808X2 middotX3 1 0000625 0000625 0543807 0475032X2 middotX4 1 00081 00081 7047734 0020994X3 middotX3 1 0472033 0472033 4107118 lt00001X3 middotX4 1 00081 00081 7047734 0020994X4 middotX4 1 0644342 0644342 7692326 lt00001Pure error 12 0013792 0001149 No clear No clear

R2 09761 Adj R2 09483 CV 325 Adeq precision 18571

6 Journal of Analytical Methods in Chemistry

34 Antioxidant Activity Analysis In this study antioxidantactivity of essential oil from the C citronella leaves wasevaluated using DPPH scavenging and 123-phentriol self-oxidation activity assays e IC50 values of essential oil aresummarized in Table 5 As reports 123-phentriol rapidlyautoxidizes in the autoxidized solution and several in-termediate products such as O2

minus were formed whichresulted in the solution to become yellow brown with aspectrum showing a shoulder between 400 and 425 nm eantioxidants could interfere with 123-phentriol autoxidationby acting as scavengers of O2

minus [11 12] erefore antioxidantability can be determined by the scavenging activity of self-oxidation of 123-phentriol Table 5 shows that both essentialoils extracted by SDE and SFE respectively had much moreeective scavenging power for self-oxidation of 123-phen-triol than BHTand ascorbic acid and it should be explored as apotential antioxidant with SFE process

Besides the model of scavenging the stable DPPH radicalis a widely used method of evaluating the free-radicalscavenging ability of natural compounds In the DPPHtest the antioxidants were able to reduce the stable DPPH

radical to the yellow-colored diphenylpicrylhydrazine eeect of antioxidants on DPPH radical scavenging wasthought to be due to their hydrogen-donating ability [12]e DPPH scavenging activity of the essential oils expressedin terms of IC50 is shown in Table 5 with the higher an-tioxidant potency of DPPH scavenging compared with theantioxidant potency of BHTand ascorbic acidereinto theessential oil extracted by SFE had the highest antioxidantpotency of DPPH scavenging

e antioxidant activities of antioxidants have been at-tributed to various mechanisms and one test is normally notenough to evaluate precisely the antioxidant activity of po-tential antioxidant [11]erefore we used these two assays toevaluate the total antioxidant capacity of essential oil from theC citronella leaves e results indicated that the essential oilhad a noticeable eect on scavenging self-oxidation of 123-phentriol and were able to scavenge free radicals

35 Antimicrobial Activity Analysis e antimicrobial ac-tivities of extracts gained from HD and SFE had been

Extraction temperature (degC)CO

2 flow (Lh)

Extr

actio

n yi

eld

()

45

44

43

42

41

40

39

38

37

36

1212

100806

040200

ndash02ndash04

ndash06ndash08

ndash10ndash12

1008

0604

0200

ndash02ndash04

ndash06ndash08

ndash10ndash12

(a)

44

43

42

41

39

40

Extraction pressure (Lh) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

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ndash04ndash06

ndash08ndash10

ndash12

(b)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction pressure (Lh)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06ndash08

ndash10ndash12

1210

0806

0402

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ndash04ndash06

ndash08ndash10

ndash12

(c)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

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ndash04ndash06

ndash08ndash10

ndash12

(d)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction time (min)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

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ndash04ndash06

ndash08ndash10

ndash12

(e)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction pressure (Lh)

Extr

actio

n yi

eld

()

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(f )

Figure 2 Response surface plot (3D and 2D) for the interactive eect of variables (a) Eect of CO2 ow and extraction temperature withxed extraction time and extraction pressure at 120min and 25Mpa respectively (b) eect of extraction time and extraction pressure withxed CO2 ow and extraction temperature at 18 Lh and 35degC respectively (c) eect of CO2 ow and extraction pressure with xedextraction time and extraction temperature at 120min and 35degC respectively (d) eect of extraction time and extraction temperature withxed CO2 ow and extraction pressure at 18 Lh and 25MPa respectively (e) eect of CO2 ow and extraction time with xed extractiontemperature and extraction pressure at 35degC and 25MPa respectively (f ) eect of extraction temperature and extraction pressure with xedCO2 ow and extraction time at 18 Lh and 120min respectively

Journal of Analytical Methods in Chemistry 7

Table 4 Chemical compositions of essential oils

No ComponentsConcentration of essential oil ()

HD SFE1 α-Pinene 071 0672 β-Pinene 431 6003 D-Limonene 02 3554 β-Ocimene ND 0155 8-Methyl 1-hendecene ND 0186 α-Guaiene 025 0457 β-Caryophyllene 246 018 α-Bergamotene ND ND9 3-Carene 046 ND10 α-Cubebene 094 04611 α-Muurolene 026 0312 c-Muurolene 167 0213 α-Copaene 129 11314 β-Bourbonene 197 ND15 β-Guaiene 014 ND

Hydrocarbons 1466 131916 Hinesol 091 2817 2-Borneol ND 07618 Isopulegol 035 01819 trans-Verbenol ND 03320 cis-Verbenol 046 09521 Nerol 035 01922 Geraniol 939 64323 trans-Farnesol ND 13424 Geraniol 2545 102225 trans-Geranylgeraniol 04 13126 3-Methyl cyclohexanol 071 20127 cis-Geranylgeraniol 035 ND28 Globulol 137 05529 c-Eucalyptol ND 08030 Carotol 037 ND31 α-Cadinol 025 14732 Cubenol 055 341

Alcohols 4091 327533 Citronellal 1277 125734 Lauraldehyde 03 01335 Neral 1115 151136 Geranialdehyde 1512 2002

Aldehydes 3934 478337 Citronellyl acetate ND 02338 Citronellyl isobutyrate 061 12739 Geraniol acetate 224 065

Esters 285 21540 D-Carvone ND 01541 D-Verbenone ND 030

Ketones 0 04542 Hexadecane 019 ND43 Dioctylmethane ND 040

Alkanes 019 04044 Rose oxide ND 01045 Geranic acid ND 01446 Eugenol 017 03347 2-Epoxy-trans-p-menthane ND 03948 Caryophyllene oxide 157 04149 3-Decyne 019 ND

Others 174 137Total identified 9969 9814ND not detected

8 Journal of Analytical Methods in Chemistry

assessed using a serial twofold dilution assay and paper discdiffusion assay according to Hu et al [23 24 26] Table 6shows the variation in the antimicrobial properties of theessential oil extracted from the C citronella leaves Amongbacterial strains the E coli has the strongest inhibitory effectby the essential oil Meanwhile the essential oil shows theantifungal or anticandidal activity as well On the otherhand more precise data concerning the antimicrobialproperties of the extracts were obtained by paper disc dif-fusion assay [26] Table 6 indicates the maximal inhibitoryzones for each of the microorganisms that were sensitive tothe extracts which were in the range of 15ndash35mmereinto the greater inhibition was observed in the case ofthe SFE extracts than the others Hence the SFE extracts wassignificant antimicrobial or antifungal activities against all ofthe microorganisms tested except A niger

In summary the SFE extracts have significant antimi-crobial activity against E coli and A niger respectivelyAntimicrobial activity in essential oil depended on mostlyaldehydes and acid esters [22 27] Recently some literaturereported there was the highest level of activity against E coliwith tea oil tannic acid and saponins [6 20 23] Ac-cordingly these observations suggested that the antimi-crobial activity of essential oil may be due to the presence ofester bond and ether bond [28] Other phenolic acid-likephenols were also thought to contribute to plant defensesagainst pests and pathogens [11]

4 Conclusions

e essential oil was attained from C citronella a commonherbaceous plant by supercritical fluid extraction resultingin 440 of essential oil extracted under mild conditionAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE Compared with HDessential oils the SFE essential oils contain fewer impuritiesand had better antioxidant and antimicrobial activitiesSupercritical fluid extraction has presented an outstandingfeature in efficient extraction of active components of the

plant which can be a desirable candidate for the currentextraction processing

Data Availability

e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was funded by the Project of Key Technologies ofHigh-Yield and Carbon Dioxide Emissions in the Full Uti-lization Process of Industrial Oil Plants (2017WK2021)National Sci-Tech Support Plan (2015BAD15B02) and Hu-nan Key Science and Technology Program (2016NK1001)

References

[1] R Pavela ldquoEssential oils for the development of eco-friendlymosquito larvicides a reviewrdquo Industrial Crops and Productsvol 76 no 4 pp 174ndash187 2015

[2] S R Sargenti and F M Lanccedilas ldquoSupercritical fluid extractionof Cymbopogon citratus (DC) Stapfrdquo Chromatographiavol 46 no 5-6 pp 285ndash290 1997

[3] V Sriramavaratharajan J Stephan V Sudha andR Murugan ldquoLeaf essential oil of Cinnamomum agasthya-malayanum from the Western Ghats India-A new source ofcamphorrdquo Industrial Crops and Products vol 86 pp 259ndash2612016

[4] R Pavela E Stepanycheva A Shchenikova T Chermenskayaand M Petrova ldquoEssential oils as prospective fumigants againstTetranychus urticae Kochrdquo Industrial Crops and Productsvol 94 pp 755ndash761 2016

[5] J R Calo P G Crandall C A OrsquoBryan and S C RickeldquoEssential oils as antimicrobials in food systems-a reviewrdquoFood Control vol 54 pp 111ndash119 2015

Table 5 Half-inhibition (IC50) values of antioxidant activities measured using DPPH radical scavenging and 123-phentriol self-oxidation

SamplesIC50 (mgg)

123-Phentriol self-oxidation DPPHSDE 274 plusmn 2 10 plusmn 1SFE 244 plusmn 3 9 plusmn 2AAlowast 5137 plusmn 4 2213 plusmn 4BHTlowast 8029 plusmn 1 895 plusmn 3lowastControl

Table 6 Minimal inhibitory concentration (MIC) of the essential oils with various extraction processes

Immature stagesInhibition zones (mm) MIC (mgmL)

S aureus E coli A niger A fumigatus S aureus E coli A niger A fumigatusSFE 178 plusmn 12 252 plusmn 09 141 plusmn 10 331 plusmn 13 56 plusmn 02 14 plusmn 01 28 plusmn 02 56 plusmn 0SDE 142 plusmn 11 196 plusmn 12 231 plusmn 11 243 plusmn 13 56 plusmn 01 28 plusmn 02 14 plusmn 01 28 plusmn 02Citrallowast 222 plusmn 06 187 plusmn 10 195 plusmn 34 146 plusmn 23 112 plusmn 05 112 plusmn 03 56 plusmn 01 112 plusmn 01lowastControl

Journal of Analytical Methods in Chemistry 9

[6] S Patel and P Gogna ldquoTapping botanicals for essential oilsprogress and hurdles in cancer mitigationrdquo Industrial Cropsand Products vol 76 pp 1148ndash1163 2015

[7] H G Huang Y E Xiao L Q Tian et al ldquoComparative studyon supercritical fluid extraction and steam distillation inextracting chemical constituents and relative contents ofvolatile oil from compatibility of Ramulus cinnamomi andRhizoma zingiberisrdquo Journal of Experimental TraditionalMedical Formulae (Chinese) vol 17 pp 85ndash92 2011

[8] R H Olmedo C M Asensio and N R Grosso ldquoermalstability and antioxidant activity of essential oils from aro-matic plants farmed in Argentinardquo Industrial Crops andProducts vol 69 no 6 pp 21ndash28 2015

[9] E Arranz L Jaime M C Lopez de las Hazas G Reglero andS Santoyo ldquoSupercritical fluid extraction as an alternativeprocess to obtain essential oils with anti-inflammatoryproperties from marjoram and sweet basilrdquo IndustrialCrops and Products vol 67 pp 121ndash129 2015

[10] A Berna A Tarrega M Blasco and S Subirats ldquoSupercriticalCO2 extraction of essential oil from orange peel effect of theheight of the bedrdquo Journal of Supercritical Fluids vol 18 no 3pp 227ndash237 2000

[11] M T Baratta H J D Dorman S G Deans A C FigueiredoJ G Barroso and G Ruberto ldquoAntimicrobial and antioxidantproperties of some commercial essential oilsrdquo Flavour andFragrance Journal vol 13 no 4 pp 235ndash244 2015

[12] H J D Dorman A C Figueiredo J G Barroso andS G Deans ldquoIn vitro evaluation of antioxidant activity ofessential oils and their componentsrdquo Flavour and FragranceJournal vol 15 no 1 pp 12ndash16 2015

[13] C Y Niu F Q Zhang D M Diao and F U Yan ldquoExtractionconditions optimization of essential oil from steamed ginsengwater by response surface methodology and GC-MS analysisrdquoScience and Technology of Food Industry (Chinese) vol 35no 18 pp 310ndash309 2014

[14] M L Harkat B Asma K Madani et al ldquoChemical com-position antibacterial and antioxidant activities of essentialoil of Eucalyptus globulus from Algeriardquo Industrial Crops andProducts vol 78 pp 148ndash153 2015

[15] H Y Kil E S Seong B K Ghimire et al ldquoAntioxidant andantimicrobial activities of crude sorghum extractrdquo FoodChemistry vol 115 no 4 pp 1234ndash1239 2009

[16] J Rakmai B Cheirsilp A Torrado-Agrasar J Simal-Gandaraand J C Mejuto ldquoEncapsulation of yarrow essential oil inhydroxypropyl-beta-cyclodextrin physiochemical character-ization and evaluation of bio-efficaciesrdquo CyTA-Journal ofFood vol 15 no 3 pp 409ndash417 2017

[17] J Rakmai B Cheirsilp J C Mejuto J Simal-Gandara andA Torrado-Agrasar ldquoAntioxidant and antimicrobial prop-erties of encapsulated guava leaf oil in hydroxypropyl-beta-cyclodextrinrdquo Industrial Crops and Products vol 111pp 219ndash225 2018

[18] J Rakmai B Cheirsilp J C Mejuto A Torrado-Agrasar andJ Simal-Gandara ldquoPhysico-chemical characterization andevaluation of bio-efficacies of black pepper essential oil en-capsulated in hydroxypropyl-beta-cyclodextrinrdquo Food Hy-drocolloids vol 65 pp 157ndash164 2016

[19] L H C Carlson R A F Machado C B SpricigoL K Pereira and A Bolzan ldquoExtraction of lemongrass es-sential oil with dense carbon dioxiderdquo Journal of SupercriticalFluids vol 21 no 1 pp 33ndash39 2001

[20] Q Qiu J LIing Y Ding H Chang J Wang and T LiuldquoComparison of supercritical fluid extraction and steamdistillation methods for the extraction of essential oils from

Schizonepeta tenuifolia briqrdquo Chromatography vol 23 no 6pp 646ndash650 2005

[21] G Sodeifian S A Sajadian and N Saadati Ardestani ldquoEx-perimental optimization and mathematical modeling of thesupercritical fluid extraction of essential oil from Eryngiumbillardieri application of simulated annealing (SA) algo-rithmrdquo Journal of Supercritical Fluids vol 127 pp 146ndash1572017

[22] A Gasparetto A Bella Cruz T M Wagner T J BonominiR Correa and A Malheiros ldquoSeasonal variation in thechemical composition antimicrobial and mutagenic potentialof essential oils from Piper cernuumrdquo Industrial Crops andProducts vol 95 pp 256ndash263 2017

[23] E Konoz N Hajikhani and A Abbasi ldquoComparison of twomethods for extraction of dill essential oil by gaschromatography-mass spectrometry coupled with chemo-metric resolution techniquesrdquo International Journal of FoodProperties vol 20 no 1 pp S1002ndashS1015 2017

[24] H J Zhang Y B Cao W B Xue H Ding G F Liu andJ Q Wang ldquoOptimization of extraction process of citronellaessential oil and its gas phase antibacterial propertiesrdquo ChinaCondiment vol 42 pp 15ndash20 2017

[25] M D Guillen N Cabo and J Burillo ldquoCharacterisation ofthe essential oils of some cultivated aromatic plants of in-dustrial interestrdquo Journal of the Science of Food and Agri-culture vol 70 no 3 pp 359ndash363 1996

[26] J Hu S Nie D Huang C Li and M Xie ldquoExtraction ofsaponin from camellia oleifera cake and evaluation of itsantioxidant activityrdquo International Journal of Food Scienceand Technology vol 47 no 8 pp 1676ndash1687 2012

[27] J Singh and N N Tripathi ldquoInhibition of storage fungi ofblackgram (Vigna mungo L) by some essential oilsrdquo Flavourand Fragrance Journal vol 14 no 1 pp 1ndash4 2015

[28] P Matusinsky M Zouhar R Pavela and P Novy ldquoAnti-fungal effect of five essential oils against important pathogenicfungi of cerealsrdquo Industrial Crops and Products vol 67pp 208ndash215 2015

10 Journal of Analytical Methods in Chemistry

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Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

Design-expert V806 was used for the experiment de-signs and subsequent regression analysis of the responsedata Statistical analysis of the model was performed toevaluate the analysis of variance (ANOVA) e quality ofthe polynomial model equation was judged statistically usingthe coefficient of determination R2 and adjustment R2 andits statistical significance was determined by the F value andP value e significance of the regression coefficients wastested by some parameters such as coefficient of variation(CV) and adequate precision

25 GC-MS Analysis e compositions of essential oilobtained by HD and SFE (in evaluated condition) wereanalyzed by a GC-MS analysis e examination was per-formed on a Scion SQ (Bruker USA) equipped with an 8400autosampler Samples were injected into the capillary col-umn in the split and splitless modes A 1 μL aliquot of testsolution was injected into a DB-5 (30m times 250 μm times 025 μmAgilent USA) e oven temperature was programmed at

5degCmin from 40degC (hold 2min) to 100degC (hold 2min) andthen 10degCmin to 250degC (hold 2min) e injector tem-perature was set at 230degC in the split and splitless modeseflow rate of the carrier gas helium was set at 1mLmin thetransmission line temperature was set at 200degC and the ionsource temperature was set at 250degC e electron ionization(EI) source operated at minus70 eV e MS spectra weremonitored in the full scan mode from 15 to 500mz with ascan event time of 03 s and a scan speed of 2000 μs esolvent delay time was set to 600min MS data analyzed byGCMS were processed by Analyzer Pro Software (Spec-tralworks Ltd Runcorn UK) including deconvolution ofmass spectra data collection alignment and normalizationMetabolite peaks were deconvoluted and collected using anarea threshold of 7000 height threshold of 1 signal to noiseratio of 3 width threshold of 001 scan windows of 5 andsmoothing of 5 e data were aligned with a retention timewindow of 03min

26 Assay of Antioxidant Activities

261 DPPH Assay e free-radical scavenging activity ofessential oil from C citronella leaves was measured by 11-diphenyl-2-picryl-hydrazyl (DPPH) assay according to themethod of [13] Ascorbic acid (AA) and 26-di-tert-butyl-4-methylphenol (BHT) were used as positive control

262 Self-Oxidation Assay e scavenging ability of 123-phentriol to self-oxidize was investigated according to themethod with a minor modification [14] AA and BHT wereused as positive control

27 Assay of Antimicrobial Activities

271 Twofold Dilution Assay Two bacterial strains and twofungal strains were used in this study Staphylococcus aureusE coli Aspergillus niger and Aspergillus fumigatus Allstrains were gained from Key Laboratory of Academy of LifeSciences in Central South University of Forestry andTechnology Hunan China e bacterial cultures weregrown in the liquid medium at a suitable temperature ebacterial strains were incubated on micrococcus nutrientand YM media and then cultured with shaking for 12 h at37degC or 30degC Two plant extracts which were respectivelycollected within SFE and HD process were screened forantimicrobial activity using a serial twofold dilution assay[15 16] e minimum inhibitory concentration (MIC) ofeach compound was defined as the lowest concentration thatinhibited microorganism growth Bacterial growth wasevaluated visually based on the degree of turbidity Citral wasused as positive control

272 Paper Disc Diffusion Assay e antimicrobial activ-ities of the plant extracts and fractions were determined bypaper disc diffusion assay [15 17 18] e diameter of eachinhibitory zone was measured (in mm) Negative controls

Table 2 Full factorial BBD matrix of three variables in coded unitsand the experimentally observed response

Runs X1 X2 X3 X4 Extraction yield ()1 110 22 35 18 4292 110 28 35 18 4213 130 22 35 18 4234 130 28 35 18 4325 120 25 32 16 4066 120 25 32 20 3917 120 25 38 16 3898 120 25 38 20 3929 110 25 35 16 42610 110 25 35 20 41111 130 25 35 16 41912 130 25 35 20 41513 120 22 32 18 40714 120 22 38 18 39415 120 28 32 18 40616 120 28 38 18 39817 110 25 32 18 39518 110 25 38 18 40219 130 25 32 18 40820 130 25 38 18 40421 120 22 35 16 42622 120 22 35 20 41123 120 28 35 16 41924 120 28 35 20 42225 120 25 35 18 43726 120 25 35 18 43627 120 25 35 18 435

Table 1 Experimental range and levels of independent variables

Variables SymbolCode levelsminus1 0 1

Extraction time (min) X1 110 120 130Extraction pressure (MPa) X2 22 25 28Extraction temperature (degC) X3 32 35 38CO2 flow (Lh) X4 16 18 20

Journal of Analytical Methods in Chemistry 3

were prepared using the same solvents employed to dissolvethe plant extracts Citral was used as positive control

28 Analytical Procedures All samples were prepared andanalyzed in triplicate All figures were obtained by using oneof Origin 85 Microsoft 2010 Design-Expert 806 andonimic 90 To verify the statistical significance of all pa-rameters the values of mean plusmn SD were calculated e yieldof essential oil obtained by HD and SFE were determined bygravimetric analysis e extraction yield () of essential oilwas calculated as follows

Y1() 100 times ρ times V1 (1)

where Y1 is the extraction yield () ρ is the destiny of theessential oil andV1 is the volume of the essential oil ecapability of scavenging the DPPH radical was calculatedusing the following equation

I() 1minus Ai minusAj1113872 1113873

Ac

⎡⎣ ⎤⎦ times 100 (2)

where Ac is the absorbance of the bland Ai is the absorbanceof the sample reacted with the DPPH and Aj is the ab-sorbance of the sample e scavenging ability of 123-phentriol of essential oil to self-oxidize was calculated usingthe following equation

Y2() 1minus S1

S21113888 1113889 times 100 (3)

where Y2 is the scavenging ability S1 is the slope of thesample and S2 is the slope of control

3 Results and Discussion

31 Determining Levels for Independent Variables In recentreports many researchers have indicated the efficiency ofextraction would be impacted significantly by some factorsin SFE processing such as extraction time extractiontemperature and CO2 flow which were respectively studiedto evaluate the impact of parameters on the SFE the resultsare shown in Figure 1 Firstly the effect of different ex-traction time periods on the extraction essential oil yield wasexamined at 30 60 90 120 and 150min in the process ofSFE e essential oil produced during SFE with respect toextraction time on extraction yield is shown in Figure 1(a)Results in the extraction yield of essential oil was increasedwith the extraction time going up from 30min to 150minWhen the extraction time was shorter than 60min the oilwas extracted significantly from the C citronella but theyield was still at a lower level At 120min the extraction yieldof essential oil reached 40 (ww on origin feedstock)ereafter the extraction yield was almost stabilizing withthe extension of time which would increase the cost of SFEtreatment erefore it is favorable to choose the range of110ndash130min as a desirable holding time for the SFE ofessential oil

Extraction temperature was one of the factors affectingextraction effectiveness According to the above results

the influence of extraction temperature at 20 25 30 35 and40degC was studied (Figure 1(b)) As seen in Figure 1(b) theextraction yield of C citronella essential oil reduced sig-nificantly with the extraction temperature going up from20degC to 40degCus there are obviously a large number of theessential oils extracted during the SFE from 26 to 40e reason maybe the viscosity of supercritical fluid de-creased and the diffusion coefficient of fluid increased withthe elevation of extraction temperature meanwhile theBrownian motion of essential oil in C citronella was en-hanced so that accelerated the processing of mass transferresulting in improving the dissolubility of oil [2] At 35degC forexample the extraction yield of essential oil increased to42 (ww in original feedstock) approximately Howeverno obvious variation in extraction yield was shown after35degC In addition the constituent and structure of essentialoil would be degraded and destructed according to somereports [8] Considering the economical and extractionefficiency 32degCndash38degC was chosen as a desirable holdingtemperature during SFE process

e influence of CO2 flow of 8 12 14 18 and 22 Lh isshown in Figure 1(c) which indicated that the flow of CO2was a notable factor influencing the extraction results Whenthe CO2 flow increased from 8 Lh to 16 Lh the extractionyield of essential oil increased sharply achieving from 24to 36 With the increasing flow of CO2 nevertheless therewas an abnormal decrease in extraction yield of essential oilSome researchers indicated that it would be conducive to thearea of effective contact between feedstock and CO2 at thelower velocity condition so that it could be much easier toextract the essential oil from original [19] Besides when theflowing of CO2 was too higher it would possibly lead to theinadequacy for the area of contact but also part of extractedoil could be brought back to the extractor from the separatorin which the mixture was not separated thoroughly for theshorter separation time It was thus of interest to obtainessential oil within limits of CO2 flow

e effects of extraction pressure on the extraction yieldof essential oil were studied with five levels at intervals of5MPa from 10 to 30MPa As illustrated in Figure 1(d) withan increase in the extraction pressure from 10 to 25MPa theyield of essential oil was significantly increased (from 27 to40) As the extraction pressure rose from 25 to 30MPa theextraction yield of essential oil changed little (sim4)is wasprobably according to the supercritical extraction principlereported by some researchers [2 7 19 20] due to theenhancement in density and diffusivity of supercritical fluidwith the increasing extraction pressure which prompted theimprovement of the strength of extraction However it wasfound that higher extraction pressure decreased the masstransfer time even carrying part of extracted essential oil in aseparator Consequently the extraction yield would bestabilized within higher extraction pressure In consider-ation of cost within the range of 22ndash28MPa was the ap-propriate extraction pressure during SFE processing in thisstudy

By comparison some recent studies had reported thatvarious factors existed in the separation reactor would havehad an influence on the yield of active substance extracted

4 Journal of Analytical Methods in Chemistry

from biomass during SFE processing [21] Accordingly somekey factors such as separation pressure and separationtemperature were evaluated for the SFE treatment in thispart As shown in Figures 1(e) and 1(f) the effect of sepa-ration pressure and separation temperature was investigatedfrom 25MPa to 45MPa and 20degC to 40degC respectively It wasabnormally apparent that the separation pressure and sepa-ration temperature resulted in an insignificant impact onextraction yield wandering in 35 approximately e resultwas beyond the expectation and inconsistent with previousresults that the subsequent separation process would play arestrictive role on extracting essential oil indicating the su-percritical CO2 had an outstanding capability of efficientextraction of essential oil with SFE which was not affected byseparation pressure and separation temperature Conse-quently in consideration of cost 3MPa and 25degC (at roomtemperature) were selected to be the separation pressure andseparation temperature in the next experiment

32 Construction of the SFE Processing After the single-factor study about the evaluation of the impact of variousparameters on the SFE treatment as shown in Figure 1 theresults had revealed the various components that changedtendency in the material including extraction time ex-traction temperature CO2 flow extraction pressure sepa-ration pressure and separation temperature respectivelyereinto the separation pressure and separation temper-ature were not considered in this experiment Although alarge number of essential oils had been extracted fromC citronella in the SFE treatment the high efficiency needs

severe treatment conditions that would increase the cost ofSFE treatment In addition it would be also increase the costbecause of interaction of various variables Accordinglythese variables were taken into careful consideration byusing BoxndashBehnken design (BBD) with the soft of Design-Expert V806 in this study

e levels of each factor are given in Table 1 Twenty-seven experiments were carried out from the design (Ta-ble 2) e results of the second-order response surfacemodel fitting for extraction yield in the form of analysis ofvariance (ANOVA) are given in Table 3 To test the fit of themodel the regression equation and determination co-efficient R2 were evaluated e model presented a highdetermination coefficient (R2 0976) explaining 976 ofthe variability in the response (Table 3) e coefficients ofregression were calculated and the following regressionequation (4) was obtained

Table 3 presents Fisherrsquos F-test of ANOVA which alsoproves that this regression model was highly statisticallysignificant (Plt 00001) At the same time the relativelylower value of the coefficient of variation (CV 325 lt 10)indicates good precision and reliability of the experimentscarried out Adequate precision for our model has a signal-to-noise ratio of 18571 (gt4) which indicates an adequatesignal e signification of each coefficient was determinedby Tand Pwhich is also listed in Table 3 which demonstratesthat all the linear model terms (X3 and X4) and quadraticmodel term (X1X2 X2X4 and X3X4) were significantMoreover the interactive model terms X1X2 X2X4 andX3X4 were significant (Plt 005) while the interactive modelterms of X1X3 X1X4 and X2X3 were insignificant (Pgt 01)

2020

25

30

35

40Ex

trac

tion

yiel

d (

)

40 60 80 100 120 140 160Extraction time (min)

(a)

25

30

35

40

20 25 30 35 40Extraction temperature (degC)

Extr

actio

n yi

eld

()

(b)

8 12 16 20 24

24

28

32

36

Extr

actio

n yi

eld

()

CO2 flow (Lh)

(c)

Extr

actio

n yi

eld

()

10

40

35

30

2515 20 25 30

Extraction pressure (MPa)

(d)

25 30 35 40 45Separate pressure (MPa)

Extr

actio

n yi

eld

()

354

351

348

345

(e)

20 25 30 35 40Separate temperature (degC)

Extr

actio

n yi

eld

()

356

354

352

350

348

346

(f )

Figure 1 Influence of various parameters on SFE efficiency for essential oil

Journal of Analytical Methods in Chemistry 5

In addition the empirical model (Eq (1)) proved that thepredicted data of the response from the empirical model are inagreement with the observed ones in the range of the op-erating variables On the other hand the value of adjusted(R2 0948) is also very high that indicated a high significanceof the model e maximum extraction yield obtained byusing above selected variables was 436 and the experi-mental maximum obtained was 432 plusmn 006 e data showthat predicted data on the response from empirical modelwere in agreement with those observed in the range of theoperating variables e coefficients of regression were cal-culated and the following regression equation was obtained

Y 437 + 0014167X1 + 0006667X2 minus 0028333X3

minus 0035833X4 minus 005625X21 + 00425X1X2

minus 00275X1X3 + 00275X1X4 minus 00525X22

+ 00125X2X3 + 0045X2X4 minus 02975X23

+ 0045X3X4 minus 012875X24

(4)

where Y response (extraction yield) X1 extraction timeX2 extraction pressure X3 extraction temperature andX4 CO2 flow in coded values

In order to gain a better understanding of the effects ofthe variables on the essential oil of extraction yield from Ccitronella leaves the predicted model was presented as 3D2D response surface graphs as shown in Figure 2 re-spectively which were generated with one variable kept at itsoptimum level and varying the others within the experi-mental range (shown in Table 1) ese variables wereoptimized as follows extraction time 120min extractionpressure 25Mpa extraction temperature 35degC and CO2 flow18 Lh for the SFE process Under optimized condition theextracted essential oil reached 440 Nevertheless the resultis comparable to that reported elsewhere on extraction ofessential oil with various extraction methods indicating thatthe SFE had significantly higher extraction efficiency and

was the most energy-saving method than other methodscombining with an auxiliary instrument that could raise thecost of production [1 5 22ndash24] Consequently these resultshave suggested that the SFE treatment is effective for se-lectively extracting the essential oil from C citronella andmay be expected to use in others active componentsextracted from various plants in future

Recently many researchers argued the extraction yieldand essential oil compositions but paid little attention to theeffect of extraction methods on the essential oil composi-tions It would limit the development and application ofessential oils [5] Accordingly in the next experimentconstitute features of the extracted oil are characterized withmodern analytical equipment

33 Analysis of the Extracted Essential Oil e chemicalcompositions identified in the essential oils extracted by HDand SFE are summarized in Table 4 ere were 35 com-pounds identified in HD essential oils while 41 in SFE es-sential oils ese compositions were grouped into sevenclasses (hydrocarbons alcohols aldehydes esters ketonesalkanes and others) according to their functional groupsAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE e abundant al-cohols can promote the C citronella leaf essential oils usedfor cosmetic applicationse contents of flavourless alkanesin SFE oil were much lower than those of SFE (Table 4)indicating that the essential oil in SFE contains fewer im-purities which were similar to the previous report [8] emain component of essential oil extracted by SFE and HDwas geranialdehyde and the next was geraniol which wereconsistent with previous studies [23 25] Furthermore thecontent of this major compound in SFE extracts was higherthan HDis proved that supercritical fluid did not alter themain effective components in C citronella essential oil butthe content of effective composition and extraction yield ofessential oil was higher [8]

Table 3 ANOVA results for the quadratic equation for the extraction yield of essential oil

Term Freedom degrees Sum of squares Mean square F value Pr gt FModel 14 0564475 004032 3508174 lt00001X1 1 0002408 0002408 2095468 0173353X2 1 0000533 0000533 0464048 0508671X3 1 0009633 0009633 8381873 0013447X4 1 0015408 0015408 1340665 0003257X1 middot X1 1 0016875 0016875 1468278 0002388X1 middotX2 1 0007225 0007225 6286405 0027545X1 middotX3 1 0003025 0003025 2632024 0130689X1 middotX4 1 0003025 0003025 2632024 0130689X2 middotX2 1 00147 00147 1279033 0003808X2 middotX3 1 0000625 0000625 0543807 0475032X2 middotX4 1 00081 00081 7047734 0020994X3 middotX3 1 0472033 0472033 4107118 lt00001X3 middotX4 1 00081 00081 7047734 0020994X4 middotX4 1 0644342 0644342 7692326 lt00001Pure error 12 0013792 0001149 No clear No clear

R2 09761 Adj R2 09483 CV 325 Adeq precision 18571

6 Journal of Analytical Methods in Chemistry

34 Antioxidant Activity Analysis In this study antioxidantactivity of essential oil from the C citronella leaves wasevaluated using DPPH scavenging and 123-phentriol self-oxidation activity assays e IC50 values of essential oil aresummarized in Table 5 As reports 123-phentriol rapidlyautoxidizes in the autoxidized solution and several in-termediate products such as O2

minus were formed whichresulted in the solution to become yellow brown with aspectrum showing a shoulder between 400 and 425 nm eantioxidants could interfere with 123-phentriol autoxidationby acting as scavengers of O2

minus [11 12] erefore antioxidantability can be determined by the scavenging activity of self-oxidation of 123-phentriol Table 5 shows that both essentialoils extracted by SDE and SFE respectively had much moreeective scavenging power for self-oxidation of 123-phen-triol than BHTand ascorbic acid and it should be explored as apotential antioxidant with SFE process

Besides the model of scavenging the stable DPPH radicalis a widely used method of evaluating the free-radicalscavenging ability of natural compounds In the DPPHtest the antioxidants were able to reduce the stable DPPH

radical to the yellow-colored diphenylpicrylhydrazine eeect of antioxidants on DPPH radical scavenging wasthought to be due to their hydrogen-donating ability [12]e DPPH scavenging activity of the essential oils expressedin terms of IC50 is shown in Table 5 with the higher an-tioxidant potency of DPPH scavenging compared with theantioxidant potency of BHTand ascorbic acidereinto theessential oil extracted by SFE had the highest antioxidantpotency of DPPH scavenging

e antioxidant activities of antioxidants have been at-tributed to various mechanisms and one test is normally notenough to evaluate precisely the antioxidant activity of po-tential antioxidant [11]erefore we used these two assays toevaluate the total antioxidant capacity of essential oil from theC citronella leaves e results indicated that the essential oilhad a noticeable eect on scavenging self-oxidation of 123-phentriol and were able to scavenge free radicals

35 Antimicrobial Activity Analysis e antimicrobial ac-tivities of extracts gained from HD and SFE had been

Extraction temperature (degC)CO

2 flow (Lh)

Extr

actio

n yi

eld

()

45

44

43

42

41

40

39

38

37

36

1212

100806

040200

ndash02ndash04

ndash06ndash08

ndash10ndash12

1008

0604

0200

ndash02ndash04

ndash06ndash08

ndash10ndash12

(a)

44

43

42

41

39

40

Extraction pressure (Lh) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(b)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction pressure (Lh)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06ndash08

ndash10ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(c)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(d)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction time (min)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(e)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction pressure (Lh)

Extr

actio

n yi

eld

()

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(f )

Figure 2 Response surface plot (3D and 2D) for the interactive eect of variables (a) Eect of CO2 ow and extraction temperature withxed extraction time and extraction pressure at 120min and 25Mpa respectively (b) eect of extraction time and extraction pressure withxed CO2 ow and extraction temperature at 18 Lh and 35degC respectively (c) eect of CO2 ow and extraction pressure with xedextraction time and extraction temperature at 120min and 35degC respectively (d) eect of extraction time and extraction temperature withxed CO2 ow and extraction pressure at 18 Lh and 25MPa respectively (e) eect of CO2 ow and extraction time with xed extractiontemperature and extraction pressure at 35degC and 25MPa respectively (f ) eect of extraction temperature and extraction pressure with xedCO2 ow and extraction time at 18 Lh and 120min respectively

Journal of Analytical Methods in Chemistry 7

Table 4 Chemical compositions of essential oils

No ComponentsConcentration of essential oil ()

HD SFE1 α-Pinene 071 0672 β-Pinene 431 6003 D-Limonene 02 3554 β-Ocimene ND 0155 8-Methyl 1-hendecene ND 0186 α-Guaiene 025 0457 β-Caryophyllene 246 018 α-Bergamotene ND ND9 3-Carene 046 ND10 α-Cubebene 094 04611 α-Muurolene 026 0312 c-Muurolene 167 0213 α-Copaene 129 11314 β-Bourbonene 197 ND15 β-Guaiene 014 ND

Hydrocarbons 1466 131916 Hinesol 091 2817 2-Borneol ND 07618 Isopulegol 035 01819 trans-Verbenol ND 03320 cis-Verbenol 046 09521 Nerol 035 01922 Geraniol 939 64323 trans-Farnesol ND 13424 Geraniol 2545 102225 trans-Geranylgeraniol 04 13126 3-Methyl cyclohexanol 071 20127 cis-Geranylgeraniol 035 ND28 Globulol 137 05529 c-Eucalyptol ND 08030 Carotol 037 ND31 α-Cadinol 025 14732 Cubenol 055 341

Alcohols 4091 327533 Citronellal 1277 125734 Lauraldehyde 03 01335 Neral 1115 151136 Geranialdehyde 1512 2002

Aldehydes 3934 478337 Citronellyl acetate ND 02338 Citronellyl isobutyrate 061 12739 Geraniol acetate 224 065

Esters 285 21540 D-Carvone ND 01541 D-Verbenone ND 030

Ketones 0 04542 Hexadecane 019 ND43 Dioctylmethane ND 040

Alkanes 019 04044 Rose oxide ND 01045 Geranic acid ND 01446 Eugenol 017 03347 2-Epoxy-trans-p-menthane ND 03948 Caryophyllene oxide 157 04149 3-Decyne 019 ND

Others 174 137Total identified 9969 9814ND not detected

8 Journal of Analytical Methods in Chemistry

assessed using a serial twofold dilution assay and paper discdiffusion assay according to Hu et al [23 24 26] Table 6shows the variation in the antimicrobial properties of theessential oil extracted from the C citronella leaves Amongbacterial strains the E coli has the strongest inhibitory effectby the essential oil Meanwhile the essential oil shows theantifungal or anticandidal activity as well On the otherhand more precise data concerning the antimicrobialproperties of the extracts were obtained by paper disc dif-fusion assay [26] Table 6 indicates the maximal inhibitoryzones for each of the microorganisms that were sensitive tothe extracts which were in the range of 15ndash35mmereinto the greater inhibition was observed in the case ofthe SFE extracts than the others Hence the SFE extracts wassignificant antimicrobial or antifungal activities against all ofthe microorganisms tested except A niger

In summary the SFE extracts have significant antimi-crobial activity against E coli and A niger respectivelyAntimicrobial activity in essential oil depended on mostlyaldehydes and acid esters [22 27] Recently some literaturereported there was the highest level of activity against E coliwith tea oil tannic acid and saponins [6 20 23] Ac-cordingly these observations suggested that the antimi-crobial activity of essential oil may be due to the presence ofester bond and ether bond [28] Other phenolic acid-likephenols were also thought to contribute to plant defensesagainst pests and pathogens [11]

4 Conclusions

e essential oil was attained from C citronella a commonherbaceous plant by supercritical fluid extraction resultingin 440 of essential oil extracted under mild conditionAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE Compared with HDessential oils the SFE essential oils contain fewer impuritiesand had better antioxidant and antimicrobial activitiesSupercritical fluid extraction has presented an outstandingfeature in efficient extraction of active components of the

plant which can be a desirable candidate for the currentextraction processing

Data Availability

e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was funded by the Project of Key Technologies ofHigh-Yield and Carbon Dioxide Emissions in the Full Uti-lization Process of Industrial Oil Plants (2017WK2021)National Sci-Tech Support Plan (2015BAD15B02) and Hu-nan Key Science and Technology Program (2016NK1001)

References

[1] R Pavela ldquoEssential oils for the development of eco-friendlymosquito larvicides a reviewrdquo Industrial Crops and Productsvol 76 no 4 pp 174ndash187 2015

[2] S R Sargenti and F M Lanccedilas ldquoSupercritical fluid extractionof Cymbopogon citratus (DC) Stapfrdquo Chromatographiavol 46 no 5-6 pp 285ndash290 1997

[3] V Sriramavaratharajan J Stephan V Sudha andR Murugan ldquoLeaf essential oil of Cinnamomum agasthya-malayanum from the Western Ghats India-A new source ofcamphorrdquo Industrial Crops and Products vol 86 pp 259ndash2612016

[4] R Pavela E Stepanycheva A Shchenikova T Chermenskayaand M Petrova ldquoEssential oils as prospective fumigants againstTetranychus urticae Kochrdquo Industrial Crops and Productsvol 94 pp 755ndash761 2016

[5] J R Calo P G Crandall C A OrsquoBryan and S C RickeldquoEssential oils as antimicrobials in food systems-a reviewrdquoFood Control vol 54 pp 111ndash119 2015

Table 5 Half-inhibition (IC50) values of antioxidant activities measured using DPPH radical scavenging and 123-phentriol self-oxidation

SamplesIC50 (mgg)

123-Phentriol self-oxidation DPPHSDE 274 plusmn 2 10 plusmn 1SFE 244 plusmn 3 9 plusmn 2AAlowast 5137 plusmn 4 2213 plusmn 4BHTlowast 8029 plusmn 1 895 plusmn 3lowastControl

Table 6 Minimal inhibitory concentration (MIC) of the essential oils with various extraction processes

Immature stagesInhibition zones (mm) MIC (mgmL)

S aureus E coli A niger A fumigatus S aureus E coli A niger A fumigatusSFE 178 plusmn 12 252 plusmn 09 141 plusmn 10 331 plusmn 13 56 plusmn 02 14 plusmn 01 28 plusmn 02 56 plusmn 0SDE 142 plusmn 11 196 plusmn 12 231 plusmn 11 243 plusmn 13 56 plusmn 01 28 plusmn 02 14 plusmn 01 28 plusmn 02Citrallowast 222 plusmn 06 187 plusmn 10 195 plusmn 34 146 plusmn 23 112 plusmn 05 112 plusmn 03 56 plusmn 01 112 plusmn 01lowastControl

Journal of Analytical Methods in Chemistry 9

[6] S Patel and P Gogna ldquoTapping botanicals for essential oilsprogress and hurdles in cancer mitigationrdquo Industrial Cropsand Products vol 76 pp 1148ndash1163 2015

[7] H G Huang Y E Xiao L Q Tian et al ldquoComparative studyon supercritical fluid extraction and steam distillation inextracting chemical constituents and relative contents ofvolatile oil from compatibility of Ramulus cinnamomi andRhizoma zingiberisrdquo Journal of Experimental TraditionalMedical Formulae (Chinese) vol 17 pp 85ndash92 2011

[8] R H Olmedo C M Asensio and N R Grosso ldquoermalstability and antioxidant activity of essential oils from aro-matic plants farmed in Argentinardquo Industrial Crops andProducts vol 69 no 6 pp 21ndash28 2015

[9] E Arranz L Jaime M C Lopez de las Hazas G Reglero andS Santoyo ldquoSupercritical fluid extraction as an alternativeprocess to obtain essential oils with anti-inflammatoryproperties from marjoram and sweet basilrdquo IndustrialCrops and Products vol 67 pp 121ndash129 2015

[10] A Berna A Tarrega M Blasco and S Subirats ldquoSupercriticalCO2 extraction of essential oil from orange peel effect of theheight of the bedrdquo Journal of Supercritical Fluids vol 18 no 3pp 227ndash237 2000

[11] M T Baratta H J D Dorman S G Deans A C FigueiredoJ G Barroso and G Ruberto ldquoAntimicrobial and antioxidantproperties of some commercial essential oilsrdquo Flavour andFragrance Journal vol 13 no 4 pp 235ndash244 2015

[12] H J D Dorman A C Figueiredo J G Barroso andS G Deans ldquoIn vitro evaluation of antioxidant activity ofessential oils and their componentsrdquo Flavour and FragranceJournal vol 15 no 1 pp 12ndash16 2015

[13] C Y Niu F Q Zhang D M Diao and F U Yan ldquoExtractionconditions optimization of essential oil from steamed ginsengwater by response surface methodology and GC-MS analysisrdquoScience and Technology of Food Industry (Chinese) vol 35no 18 pp 310ndash309 2014

[14] M L Harkat B Asma K Madani et al ldquoChemical com-position antibacterial and antioxidant activities of essentialoil of Eucalyptus globulus from Algeriardquo Industrial Crops andProducts vol 78 pp 148ndash153 2015

[15] H Y Kil E S Seong B K Ghimire et al ldquoAntioxidant andantimicrobial activities of crude sorghum extractrdquo FoodChemistry vol 115 no 4 pp 1234ndash1239 2009

[16] J Rakmai B Cheirsilp A Torrado-Agrasar J Simal-Gandaraand J C Mejuto ldquoEncapsulation of yarrow essential oil inhydroxypropyl-beta-cyclodextrin physiochemical character-ization and evaluation of bio-efficaciesrdquo CyTA-Journal ofFood vol 15 no 3 pp 409ndash417 2017

[17] J Rakmai B Cheirsilp J C Mejuto J Simal-Gandara andA Torrado-Agrasar ldquoAntioxidant and antimicrobial prop-erties of encapsulated guava leaf oil in hydroxypropyl-beta-cyclodextrinrdquo Industrial Crops and Products vol 111pp 219ndash225 2018

[18] J Rakmai B Cheirsilp J C Mejuto A Torrado-Agrasar andJ Simal-Gandara ldquoPhysico-chemical characterization andevaluation of bio-efficacies of black pepper essential oil en-capsulated in hydroxypropyl-beta-cyclodextrinrdquo Food Hy-drocolloids vol 65 pp 157ndash164 2016

[19] L H C Carlson R A F Machado C B SpricigoL K Pereira and A Bolzan ldquoExtraction of lemongrass es-sential oil with dense carbon dioxiderdquo Journal of SupercriticalFluids vol 21 no 1 pp 33ndash39 2001

[20] Q Qiu J LIing Y Ding H Chang J Wang and T LiuldquoComparison of supercritical fluid extraction and steamdistillation methods for the extraction of essential oils from

Schizonepeta tenuifolia briqrdquo Chromatography vol 23 no 6pp 646ndash650 2005

[21] G Sodeifian S A Sajadian and N Saadati Ardestani ldquoEx-perimental optimization and mathematical modeling of thesupercritical fluid extraction of essential oil from Eryngiumbillardieri application of simulated annealing (SA) algo-rithmrdquo Journal of Supercritical Fluids vol 127 pp 146ndash1572017

[22] A Gasparetto A Bella Cruz T M Wagner T J BonominiR Correa and A Malheiros ldquoSeasonal variation in thechemical composition antimicrobial and mutagenic potentialof essential oils from Piper cernuumrdquo Industrial Crops andProducts vol 95 pp 256ndash263 2017

[23] E Konoz N Hajikhani and A Abbasi ldquoComparison of twomethods for extraction of dill essential oil by gaschromatography-mass spectrometry coupled with chemo-metric resolution techniquesrdquo International Journal of FoodProperties vol 20 no 1 pp S1002ndashS1015 2017

[24] H J Zhang Y B Cao W B Xue H Ding G F Liu andJ Q Wang ldquoOptimization of extraction process of citronellaessential oil and its gas phase antibacterial propertiesrdquo ChinaCondiment vol 42 pp 15ndash20 2017

[25] M D Guillen N Cabo and J Burillo ldquoCharacterisation ofthe essential oils of some cultivated aromatic plants of in-dustrial interestrdquo Journal of the Science of Food and Agri-culture vol 70 no 3 pp 359ndash363 1996

[26] J Hu S Nie D Huang C Li and M Xie ldquoExtraction ofsaponin from camellia oleifera cake and evaluation of itsantioxidant activityrdquo International Journal of Food Scienceand Technology vol 47 no 8 pp 1676ndash1687 2012

[27] J Singh and N N Tripathi ldquoInhibition of storage fungi ofblackgram (Vigna mungo L) by some essential oilsrdquo Flavourand Fragrance Journal vol 14 no 1 pp 1ndash4 2015

[28] P Matusinsky M Zouhar R Pavela and P Novy ldquoAnti-fungal effect of five essential oils against important pathogenicfungi of cerealsrdquo Industrial Crops and Products vol 67pp 208ndash215 2015

10 Journal of Analytical Methods in Chemistry

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Submit your manuscripts atwwwhindawicom

were prepared using the same solvents employed to dissolvethe plant extracts Citral was used as positive control

28 Analytical Procedures All samples were prepared andanalyzed in triplicate All figures were obtained by using oneof Origin 85 Microsoft 2010 Design-Expert 806 andonimic 90 To verify the statistical significance of all pa-rameters the values of mean plusmn SD were calculated e yieldof essential oil obtained by HD and SFE were determined bygravimetric analysis e extraction yield () of essential oilwas calculated as follows

Y1() 100 times ρ times V1 (1)

where Y1 is the extraction yield () ρ is the destiny of theessential oil andV1 is the volume of the essential oil ecapability of scavenging the DPPH radical was calculatedusing the following equation

I() 1minus Ai minusAj1113872 1113873

Ac

⎡⎣ ⎤⎦ times 100 (2)

where Ac is the absorbance of the bland Ai is the absorbanceof the sample reacted with the DPPH and Aj is the ab-sorbance of the sample e scavenging ability of 123-phentriol of essential oil to self-oxidize was calculated usingthe following equation

Y2() 1minus S1

S21113888 1113889 times 100 (3)

where Y2 is the scavenging ability S1 is the slope of thesample and S2 is the slope of control

3 Results and Discussion

31 Determining Levels for Independent Variables In recentreports many researchers have indicated the efficiency ofextraction would be impacted significantly by some factorsin SFE processing such as extraction time extractiontemperature and CO2 flow which were respectively studiedto evaluate the impact of parameters on the SFE the resultsare shown in Figure 1 Firstly the effect of different ex-traction time periods on the extraction essential oil yield wasexamined at 30 60 90 120 and 150min in the process ofSFE e essential oil produced during SFE with respect toextraction time on extraction yield is shown in Figure 1(a)Results in the extraction yield of essential oil was increasedwith the extraction time going up from 30min to 150minWhen the extraction time was shorter than 60min the oilwas extracted significantly from the C citronella but theyield was still at a lower level At 120min the extraction yieldof essential oil reached 40 (ww on origin feedstock)ereafter the extraction yield was almost stabilizing withthe extension of time which would increase the cost of SFEtreatment erefore it is favorable to choose the range of110ndash130min as a desirable holding time for the SFE ofessential oil

Extraction temperature was one of the factors affectingextraction effectiveness According to the above results

the influence of extraction temperature at 20 25 30 35 and40degC was studied (Figure 1(b)) As seen in Figure 1(b) theextraction yield of C citronella essential oil reduced sig-nificantly with the extraction temperature going up from20degC to 40degCus there are obviously a large number of theessential oils extracted during the SFE from 26 to 40e reason maybe the viscosity of supercritical fluid de-creased and the diffusion coefficient of fluid increased withthe elevation of extraction temperature meanwhile theBrownian motion of essential oil in C citronella was en-hanced so that accelerated the processing of mass transferresulting in improving the dissolubility of oil [2] At 35degC forexample the extraction yield of essential oil increased to42 (ww in original feedstock) approximately Howeverno obvious variation in extraction yield was shown after35degC In addition the constituent and structure of essentialoil would be degraded and destructed according to somereports [8] Considering the economical and extractionefficiency 32degCndash38degC was chosen as a desirable holdingtemperature during SFE process

e influence of CO2 flow of 8 12 14 18 and 22 Lh isshown in Figure 1(c) which indicated that the flow of CO2was a notable factor influencing the extraction results Whenthe CO2 flow increased from 8 Lh to 16 Lh the extractionyield of essential oil increased sharply achieving from 24to 36 With the increasing flow of CO2 nevertheless therewas an abnormal decrease in extraction yield of essential oilSome researchers indicated that it would be conducive to thearea of effective contact between feedstock and CO2 at thelower velocity condition so that it could be much easier toextract the essential oil from original [19] Besides when theflowing of CO2 was too higher it would possibly lead to theinadequacy for the area of contact but also part of extractedoil could be brought back to the extractor from the separatorin which the mixture was not separated thoroughly for theshorter separation time It was thus of interest to obtainessential oil within limits of CO2 flow

e effects of extraction pressure on the extraction yieldof essential oil were studied with five levels at intervals of5MPa from 10 to 30MPa As illustrated in Figure 1(d) withan increase in the extraction pressure from 10 to 25MPa theyield of essential oil was significantly increased (from 27 to40) As the extraction pressure rose from 25 to 30MPa theextraction yield of essential oil changed little (sim4)is wasprobably according to the supercritical extraction principlereported by some researchers [2 7 19 20] due to theenhancement in density and diffusivity of supercritical fluidwith the increasing extraction pressure which prompted theimprovement of the strength of extraction However it wasfound that higher extraction pressure decreased the masstransfer time even carrying part of extracted essential oil in aseparator Consequently the extraction yield would bestabilized within higher extraction pressure In consider-ation of cost within the range of 22ndash28MPa was the ap-propriate extraction pressure during SFE processing in thisstudy

By comparison some recent studies had reported thatvarious factors existed in the separation reactor would havehad an influence on the yield of active substance extracted

4 Journal of Analytical Methods in Chemistry

from biomass during SFE processing [21] Accordingly somekey factors such as separation pressure and separationtemperature were evaluated for the SFE treatment in thispart As shown in Figures 1(e) and 1(f) the effect of sepa-ration pressure and separation temperature was investigatedfrom 25MPa to 45MPa and 20degC to 40degC respectively It wasabnormally apparent that the separation pressure and sepa-ration temperature resulted in an insignificant impact onextraction yield wandering in 35 approximately e resultwas beyond the expectation and inconsistent with previousresults that the subsequent separation process would play arestrictive role on extracting essential oil indicating the su-percritical CO2 had an outstanding capability of efficientextraction of essential oil with SFE which was not affected byseparation pressure and separation temperature Conse-quently in consideration of cost 3MPa and 25degC (at roomtemperature) were selected to be the separation pressure andseparation temperature in the next experiment

32 Construction of the SFE Processing After the single-factor study about the evaluation of the impact of variousparameters on the SFE treatment as shown in Figure 1 theresults had revealed the various components that changedtendency in the material including extraction time ex-traction temperature CO2 flow extraction pressure sepa-ration pressure and separation temperature respectivelyereinto the separation pressure and separation temper-ature were not considered in this experiment Although alarge number of essential oils had been extracted fromC citronella in the SFE treatment the high efficiency needs

severe treatment conditions that would increase the cost ofSFE treatment In addition it would be also increase the costbecause of interaction of various variables Accordinglythese variables were taken into careful consideration byusing BoxndashBehnken design (BBD) with the soft of Design-Expert V806 in this study

e levels of each factor are given in Table 1 Twenty-seven experiments were carried out from the design (Ta-ble 2) e results of the second-order response surfacemodel fitting for extraction yield in the form of analysis ofvariance (ANOVA) are given in Table 3 To test the fit of themodel the regression equation and determination co-efficient R2 were evaluated e model presented a highdetermination coefficient (R2 0976) explaining 976 ofthe variability in the response (Table 3) e coefficients ofregression were calculated and the following regressionequation (4) was obtained

Table 3 presents Fisherrsquos F-test of ANOVA which alsoproves that this regression model was highly statisticallysignificant (Plt 00001) At the same time the relativelylower value of the coefficient of variation (CV 325 lt 10)indicates good precision and reliability of the experimentscarried out Adequate precision for our model has a signal-to-noise ratio of 18571 (gt4) which indicates an adequatesignal e signification of each coefficient was determinedby Tand Pwhich is also listed in Table 3 which demonstratesthat all the linear model terms (X3 and X4) and quadraticmodel term (X1X2 X2X4 and X3X4) were significantMoreover the interactive model terms X1X2 X2X4 andX3X4 were significant (Plt 005) while the interactive modelterms of X1X3 X1X4 and X2X3 were insignificant (Pgt 01)

2020

25

30

35

40Ex

trac

tion

yiel

d (

)

40 60 80 100 120 140 160Extraction time (min)

(a)

25

30

35

40

20 25 30 35 40Extraction temperature (degC)

Extr

actio

n yi

eld

()

(b)

8 12 16 20 24

24

28

32

36

Extr

actio

n yi

eld

()

CO2 flow (Lh)

(c)

Extr

actio

n yi

eld

()

10

40

35

30

2515 20 25 30

Extraction pressure (MPa)

(d)

25 30 35 40 45Separate pressure (MPa)

Extr

actio

n yi

eld

()

354

351

348

345

(e)

20 25 30 35 40Separate temperature (degC)

Extr

actio

n yi

eld

()

356

354

352

350

348

346

(f )

Figure 1 Influence of various parameters on SFE efficiency for essential oil

Journal of Analytical Methods in Chemistry 5

In addition the empirical model (Eq (1)) proved that thepredicted data of the response from the empirical model are inagreement with the observed ones in the range of the op-erating variables On the other hand the value of adjusted(R2 0948) is also very high that indicated a high significanceof the model e maximum extraction yield obtained byusing above selected variables was 436 and the experi-mental maximum obtained was 432 plusmn 006 e data showthat predicted data on the response from empirical modelwere in agreement with those observed in the range of theoperating variables e coefficients of regression were cal-culated and the following regression equation was obtained

Y 437 + 0014167X1 + 0006667X2 minus 0028333X3

minus 0035833X4 minus 005625X21 + 00425X1X2

minus 00275X1X3 + 00275X1X4 minus 00525X22

+ 00125X2X3 + 0045X2X4 minus 02975X23

+ 0045X3X4 minus 012875X24

(4)

where Y response (extraction yield) X1 extraction timeX2 extraction pressure X3 extraction temperature andX4 CO2 flow in coded values

In order to gain a better understanding of the effects ofthe variables on the essential oil of extraction yield from Ccitronella leaves the predicted model was presented as 3D2D response surface graphs as shown in Figure 2 re-spectively which were generated with one variable kept at itsoptimum level and varying the others within the experi-mental range (shown in Table 1) ese variables wereoptimized as follows extraction time 120min extractionpressure 25Mpa extraction temperature 35degC and CO2 flow18 Lh for the SFE process Under optimized condition theextracted essential oil reached 440 Nevertheless the resultis comparable to that reported elsewhere on extraction ofessential oil with various extraction methods indicating thatthe SFE had significantly higher extraction efficiency and

was the most energy-saving method than other methodscombining with an auxiliary instrument that could raise thecost of production [1 5 22ndash24] Consequently these resultshave suggested that the SFE treatment is effective for se-lectively extracting the essential oil from C citronella andmay be expected to use in others active componentsextracted from various plants in future

Recently many researchers argued the extraction yieldand essential oil compositions but paid little attention to theeffect of extraction methods on the essential oil composi-tions It would limit the development and application ofessential oils [5] Accordingly in the next experimentconstitute features of the extracted oil are characterized withmodern analytical equipment

33 Analysis of the Extracted Essential Oil e chemicalcompositions identified in the essential oils extracted by HDand SFE are summarized in Table 4 ere were 35 com-pounds identified in HD essential oils while 41 in SFE es-sential oils ese compositions were grouped into sevenclasses (hydrocarbons alcohols aldehydes esters ketonesalkanes and others) according to their functional groupsAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE e abundant al-cohols can promote the C citronella leaf essential oils usedfor cosmetic applicationse contents of flavourless alkanesin SFE oil were much lower than those of SFE (Table 4)indicating that the essential oil in SFE contains fewer im-purities which were similar to the previous report [8] emain component of essential oil extracted by SFE and HDwas geranialdehyde and the next was geraniol which wereconsistent with previous studies [23 25] Furthermore thecontent of this major compound in SFE extracts was higherthan HDis proved that supercritical fluid did not alter themain effective components in C citronella essential oil butthe content of effective composition and extraction yield ofessential oil was higher [8]

Table 3 ANOVA results for the quadratic equation for the extraction yield of essential oil

Term Freedom degrees Sum of squares Mean square F value Pr gt FModel 14 0564475 004032 3508174 lt00001X1 1 0002408 0002408 2095468 0173353X2 1 0000533 0000533 0464048 0508671X3 1 0009633 0009633 8381873 0013447X4 1 0015408 0015408 1340665 0003257X1 middot X1 1 0016875 0016875 1468278 0002388X1 middotX2 1 0007225 0007225 6286405 0027545X1 middotX3 1 0003025 0003025 2632024 0130689X1 middotX4 1 0003025 0003025 2632024 0130689X2 middotX2 1 00147 00147 1279033 0003808X2 middotX3 1 0000625 0000625 0543807 0475032X2 middotX4 1 00081 00081 7047734 0020994X3 middotX3 1 0472033 0472033 4107118 lt00001X3 middotX4 1 00081 00081 7047734 0020994X4 middotX4 1 0644342 0644342 7692326 lt00001Pure error 12 0013792 0001149 No clear No clear

R2 09761 Adj R2 09483 CV 325 Adeq precision 18571

6 Journal of Analytical Methods in Chemistry

34 Antioxidant Activity Analysis In this study antioxidantactivity of essential oil from the C citronella leaves wasevaluated using DPPH scavenging and 123-phentriol self-oxidation activity assays e IC50 values of essential oil aresummarized in Table 5 As reports 123-phentriol rapidlyautoxidizes in the autoxidized solution and several in-termediate products such as O2

minus were formed whichresulted in the solution to become yellow brown with aspectrum showing a shoulder between 400 and 425 nm eantioxidants could interfere with 123-phentriol autoxidationby acting as scavengers of O2

minus [11 12] erefore antioxidantability can be determined by the scavenging activity of self-oxidation of 123-phentriol Table 5 shows that both essentialoils extracted by SDE and SFE respectively had much moreeective scavenging power for self-oxidation of 123-phen-triol than BHTand ascorbic acid and it should be explored as apotential antioxidant with SFE process

Besides the model of scavenging the stable DPPH radicalis a widely used method of evaluating the free-radicalscavenging ability of natural compounds In the DPPHtest the antioxidants were able to reduce the stable DPPH

radical to the yellow-colored diphenylpicrylhydrazine eeect of antioxidants on DPPH radical scavenging wasthought to be due to their hydrogen-donating ability [12]e DPPH scavenging activity of the essential oils expressedin terms of IC50 is shown in Table 5 with the higher an-tioxidant potency of DPPH scavenging compared with theantioxidant potency of BHTand ascorbic acidereinto theessential oil extracted by SFE had the highest antioxidantpotency of DPPH scavenging

e antioxidant activities of antioxidants have been at-tributed to various mechanisms and one test is normally notenough to evaluate precisely the antioxidant activity of po-tential antioxidant [11]erefore we used these two assays toevaluate the total antioxidant capacity of essential oil from theC citronella leaves e results indicated that the essential oilhad a noticeable eect on scavenging self-oxidation of 123-phentriol and were able to scavenge free radicals

35 Antimicrobial Activity Analysis e antimicrobial ac-tivities of extracts gained from HD and SFE had been

Extraction temperature (degC)CO

2 flow (Lh)

Extr

actio

n yi

eld

()

45

44

43

42

41

40

39

38

37

36

1212

100806

040200

ndash02ndash04

ndash06ndash08

ndash10ndash12

1008

0604

0200

ndash02ndash04

ndash06ndash08

ndash10ndash12

(a)

44

43

42

41

39

40

Extraction pressure (Lh) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(b)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction pressure (Lh)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06ndash08

ndash10ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(c)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(d)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction time (min)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(e)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction pressure (Lh)

Extr

actio

n yi

eld

()

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(f )

Figure 2 Response surface plot (3D and 2D) for the interactive eect of variables (a) Eect of CO2 ow and extraction temperature withxed extraction time and extraction pressure at 120min and 25Mpa respectively (b) eect of extraction time and extraction pressure withxed CO2 ow and extraction temperature at 18 Lh and 35degC respectively (c) eect of CO2 ow and extraction pressure with xedextraction time and extraction temperature at 120min and 35degC respectively (d) eect of extraction time and extraction temperature withxed CO2 ow and extraction pressure at 18 Lh and 25MPa respectively (e) eect of CO2 ow and extraction time with xed extractiontemperature and extraction pressure at 35degC and 25MPa respectively (f ) eect of extraction temperature and extraction pressure with xedCO2 ow and extraction time at 18 Lh and 120min respectively

Journal of Analytical Methods in Chemistry 7

Table 4 Chemical compositions of essential oils

No ComponentsConcentration of essential oil ()

HD SFE1 α-Pinene 071 0672 β-Pinene 431 6003 D-Limonene 02 3554 β-Ocimene ND 0155 8-Methyl 1-hendecene ND 0186 α-Guaiene 025 0457 β-Caryophyllene 246 018 α-Bergamotene ND ND9 3-Carene 046 ND10 α-Cubebene 094 04611 α-Muurolene 026 0312 c-Muurolene 167 0213 α-Copaene 129 11314 β-Bourbonene 197 ND15 β-Guaiene 014 ND

Hydrocarbons 1466 131916 Hinesol 091 2817 2-Borneol ND 07618 Isopulegol 035 01819 trans-Verbenol ND 03320 cis-Verbenol 046 09521 Nerol 035 01922 Geraniol 939 64323 trans-Farnesol ND 13424 Geraniol 2545 102225 trans-Geranylgeraniol 04 13126 3-Methyl cyclohexanol 071 20127 cis-Geranylgeraniol 035 ND28 Globulol 137 05529 c-Eucalyptol ND 08030 Carotol 037 ND31 α-Cadinol 025 14732 Cubenol 055 341

Alcohols 4091 327533 Citronellal 1277 125734 Lauraldehyde 03 01335 Neral 1115 151136 Geranialdehyde 1512 2002

Aldehydes 3934 478337 Citronellyl acetate ND 02338 Citronellyl isobutyrate 061 12739 Geraniol acetate 224 065

Esters 285 21540 D-Carvone ND 01541 D-Verbenone ND 030

Ketones 0 04542 Hexadecane 019 ND43 Dioctylmethane ND 040

Alkanes 019 04044 Rose oxide ND 01045 Geranic acid ND 01446 Eugenol 017 03347 2-Epoxy-trans-p-menthane ND 03948 Caryophyllene oxide 157 04149 3-Decyne 019 ND

Others 174 137Total identified 9969 9814ND not detected

8 Journal of Analytical Methods in Chemistry

assessed using a serial twofold dilution assay and paper discdiffusion assay according to Hu et al [23 24 26] Table 6shows the variation in the antimicrobial properties of theessential oil extracted from the C citronella leaves Amongbacterial strains the E coli has the strongest inhibitory effectby the essential oil Meanwhile the essential oil shows theantifungal or anticandidal activity as well On the otherhand more precise data concerning the antimicrobialproperties of the extracts were obtained by paper disc dif-fusion assay [26] Table 6 indicates the maximal inhibitoryzones for each of the microorganisms that were sensitive tothe extracts which were in the range of 15ndash35mmereinto the greater inhibition was observed in the case ofthe SFE extracts than the others Hence the SFE extracts wassignificant antimicrobial or antifungal activities against all ofthe microorganisms tested except A niger

In summary the SFE extracts have significant antimi-crobial activity against E coli and A niger respectivelyAntimicrobial activity in essential oil depended on mostlyaldehydes and acid esters [22 27] Recently some literaturereported there was the highest level of activity against E coliwith tea oil tannic acid and saponins [6 20 23] Ac-cordingly these observations suggested that the antimi-crobial activity of essential oil may be due to the presence ofester bond and ether bond [28] Other phenolic acid-likephenols were also thought to contribute to plant defensesagainst pests and pathogens [11]

4 Conclusions

e essential oil was attained from C citronella a commonherbaceous plant by supercritical fluid extraction resultingin 440 of essential oil extracted under mild conditionAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE Compared with HDessential oils the SFE essential oils contain fewer impuritiesand had better antioxidant and antimicrobial activitiesSupercritical fluid extraction has presented an outstandingfeature in efficient extraction of active components of the

plant which can be a desirable candidate for the currentextraction processing

Data Availability

e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was funded by the Project of Key Technologies ofHigh-Yield and Carbon Dioxide Emissions in the Full Uti-lization Process of Industrial Oil Plants (2017WK2021)National Sci-Tech Support Plan (2015BAD15B02) and Hu-nan Key Science and Technology Program (2016NK1001)

References

[1] R Pavela ldquoEssential oils for the development of eco-friendlymosquito larvicides a reviewrdquo Industrial Crops and Productsvol 76 no 4 pp 174ndash187 2015

[2] S R Sargenti and F M Lanccedilas ldquoSupercritical fluid extractionof Cymbopogon citratus (DC) Stapfrdquo Chromatographiavol 46 no 5-6 pp 285ndash290 1997

[3] V Sriramavaratharajan J Stephan V Sudha andR Murugan ldquoLeaf essential oil of Cinnamomum agasthya-malayanum from the Western Ghats India-A new source ofcamphorrdquo Industrial Crops and Products vol 86 pp 259ndash2612016

[4] R Pavela E Stepanycheva A Shchenikova T Chermenskayaand M Petrova ldquoEssential oils as prospective fumigants againstTetranychus urticae Kochrdquo Industrial Crops and Productsvol 94 pp 755ndash761 2016

[5] J R Calo P G Crandall C A OrsquoBryan and S C RickeldquoEssential oils as antimicrobials in food systems-a reviewrdquoFood Control vol 54 pp 111ndash119 2015

Table 5 Half-inhibition (IC50) values of antioxidant activities measured using DPPH radical scavenging and 123-phentriol self-oxidation

SamplesIC50 (mgg)

123-Phentriol self-oxidation DPPHSDE 274 plusmn 2 10 plusmn 1SFE 244 plusmn 3 9 plusmn 2AAlowast 5137 plusmn 4 2213 plusmn 4BHTlowast 8029 plusmn 1 895 plusmn 3lowastControl

Table 6 Minimal inhibitory concentration (MIC) of the essential oils with various extraction processes

Immature stagesInhibition zones (mm) MIC (mgmL)

S aureus E coli A niger A fumigatus S aureus E coli A niger A fumigatusSFE 178 plusmn 12 252 plusmn 09 141 plusmn 10 331 plusmn 13 56 plusmn 02 14 plusmn 01 28 plusmn 02 56 plusmn 0SDE 142 plusmn 11 196 plusmn 12 231 plusmn 11 243 plusmn 13 56 plusmn 01 28 plusmn 02 14 plusmn 01 28 plusmn 02Citrallowast 222 plusmn 06 187 plusmn 10 195 plusmn 34 146 plusmn 23 112 plusmn 05 112 plusmn 03 56 plusmn 01 112 plusmn 01lowastControl

Journal of Analytical Methods in Chemistry 9

[6] S Patel and P Gogna ldquoTapping botanicals for essential oilsprogress and hurdles in cancer mitigationrdquo Industrial Cropsand Products vol 76 pp 1148ndash1163 2015

[7] H G Huang Y E Xiao L Q Tian et al ldquoComparative studyon supercritical fluid extraction and steam distillation inextracting chemical constituents and relative contents ofvolatile oil from compatibility of Ramulus cinnamomi andRhizoma zingiberisrdquo Journal of Experimental TraditionalMedical Formulae (Chinese) vol 17 pp 85ndash92 2011

[8] R H Olmedo C M Asensio and N R Grosso ldquoermalstability and antioxidant activity of essential oils from aro-matic plants farmed in Argentinardquo Industrial Crops andProducts vol 69 no 6 pp 21ndash28 2015

[9] E Arranz L Jaime M C Lopez de las Hazas G Reglero andS Santoyo ldquoSupercritical fluid extraction as an alternativeprocess to obtain essential oils with anti-inflammatoryproperties from marjoram and sweet basilrdquo IndustrialCrops and Products vol 67 pp 121ndash129 2015

[10] A Berna A Tarrega M Blasco and S Subirats ldquoSupercriticalCO2 extraction of essential oil from orange peel effect of theheight of the bedrdquo Journal of Supercritical Fluids vol 18 no 3pp 227ndash237 2000

[11] M T Baratta H J D Dorman S G Deans A C FigueiredoJ G Barroso and G Ruberto ldquoAntimicrobial and antioxidantproperties of some commercial essential oilsrdquo Flavour andFragrance Journal vol 13 no 4 pp 235ndash244 2015

[12] H J D Dorman A C Figueiredo J G Barroso andS G Deans ldquoIn vitro evaluation of antioxidant activity ofessential oils and their componentsrdquo Flavour and FragranceJournal vol 15 no 1 pp 12ndash16 2015

[13] C Y Niu F Q Zhang D M Diao and F U Yan ldquoExtractionconditions optimization of essential oil from steamed ginsengwater by response surface methodology and GC-MS analysisrdquoScience and Technology of Food Industry (Chinese) vol 35no 18 pp 310ndash309 2014

[14] M L Harkat B Asma K Madani et al ldquoChemical com-position antibacterial and antioxidant activities of essentialoil of Eucalyptus globulus from Algeriardquo Industrial Crops andProducts vol 78 pp 148ndash153 2015

[15] H Y Kil E S Seong B K Ghimire et al ldquoAntioxidant andantimicrobial activities of crude sorghum extractrdquo FoodChemistry vol 115 no 4 pp 1234ndash1239 2009

[16] J Rakmai B Cheirsilp A Torrado-Agrasar J Simal-Gandaraand J C Mejuto ldquoEncapsulation of yarrow essential oil inhydroxypropyl-beta-cyclodextrin physiochemical character-ization and evaluation of bio-efficaciesrdquo CyTA-Journal ofFood vol 15 no 3 pp 409ndash417 2017

[17] J Rakmai B Cheirsilp J C Mejuto J Simal-Gandara andA Torrado-Agrasar ldquoAntioxidant and antimicrobial prop-erties of encapsulated guava leaf oil in hydroxypropyl-beta-cyclodextrinrdquo Industrial Crops and Products vol 111pp 219ndash225 2018

[18] J Rakmai B Cheirsilp J C Mejuto A Torrado-Agrasar andJ Simal-Gandara ldquoPhysico-chemical characterization andevaluation of bio-efficacies of black pepper essential oil en-capsulated in hydroxypropyl-beta-cyclodextrinrdquo Food Hy-drocolloids vol 65 pp 157ndash164 2016

[19] L H C Carlson R A F Machado C B SpricigoL K Pereira and A Bolzan ldquoExtraction of lemongrass es-sential oil with dense carbon dioxiderdquo Journal of SupercriticalFluids vol 21 no 1 pp 33ndash39 2001

[20] Q Qiu J LIing Y Ding H Chang J Wang and T LiuldquoComparison of supercritical fluid extraction and steamdistillation methods for the extraction of essential oils from

Schizonepeta tenuifolia briqrdquo Chromatography vol 23 no 6pp 646ndash650 2005

[21] G Sodeifian S A Sajadian and N Saadati Ardestani ldquoEx-perimental optimization and mathematical modeling of thesupercritical fluid extraction of essential oil from Eryngiumbillardieri application of simulated annealing (SA) algo-rithmrdquo Journal of Supercritical Fluids vol 127 pp 146ndash1572017

[22] A Gasparetto A Bella Cruz T M Wagner T J BonominiR Correa and A Malheiros ldquoSeasonal variation in thechemical composition antimicrobial and mutagenic potentialof essential oils from Piper cernuumrdquo Industrial Crops andProducts vol 95 pp 256ndash263 2017

[23] E Konoz N Hajikhani and A Abbasi ldquoComparison of twomethods for extraction of dill essential oil by gaschromatography-mass spectrometry coupled with chemo-metric resolution techniquesrdquo International Journal of FoodProperties vol 20 no 1 pp S1002ndashS1015 2017

[24] H J Zhang Y B Cao W B Xue H Ding G F Liu andJ Q Wang ldquoOptimization of extraction process of citronellaessential oil and its gas phase antibacterial propertiesrdquo ChinaCondiment vol 42 pp 15ndash20 2017

[25] M D Guillen N Cabo and J Burillo ldquoCharacterisation ofthe essential oils of some cultivated aromatic plants of in-dustrial interestrdquo Journal of the Science of Food and Agri-culture vol 70 no 3 pp 359ndash363 1996

[26] J Hu S Nie D Huang C Li and M Xie ldquoExtraction ofsaponin from camellia oleifera cake and evaluation of itsantioxidant activityrdquo International Journal of Food Scienceand Technology vol 47 no 8 pp 1676ndash1687 2012

[27] J Singh and N N Tripathi ldquoInhibition of storage fungi ofblackgram (Vigna mungo L) by some essential oilsrdquo Flavourand Fragrance Journal vol 14 no 1 pp 1ndash4 2015

[28] P Matusinsky M Zouhar R Pavela and P Novy ldquoAnti-fungal effect of five essential oils against important pathogenicfungi of cerealsrdquo Industrial Crops and Products vol 67pp 208ndash215 2015

10 Journal of Analytical Methods in Chemistry

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Submit your manuscripts atwwwhindawicom

from biomass during SFE processing [21] Accordingly somekey factors such as separation pressure and separationtemperature were evaluated for the SFE treatment in thispart As shown in Figures 1(e) and 1(f) the effect of sepa-ration pressure and separation temperature was investigatedfrom 25MPa to 45MPa and 20degC to 40degC respectively It wasabnormally apparent that the separation pressure and sepa-ration temperature resulted in an insignificant impact onextraction yield wandering in 35 approximately e resultwas beyond the expectation and inconsistent with previousresults that the subsequent separation process would play arestrictive role on extracting essential oil indicating the su-percritical CO2 had an outstanding capability of efficientextraction of essential oil with SFE which was not affected byseparation pressure and separation temperature Conse-quently in consideration of cost 3MPa and 25degC (at roomtemperature) were selected to be the separation pressure andseparation temperature in the next experiment

32 Construction of the SFE Processing After the single-factor study about the evaluation of the impact of variousparameters on the SFE treatment as shown in Figure 1 theresults had revealed the various components that changedtendency in the material including extraction time ex-traction temperature CO2 flow extraction pressure sepa-ration pressure and separation temperature respectivelyereinto the separation pressure and separation temper-ature were not considered in this experiment Although alarge number of essential oils had been extracted fromC citronella in the SFE treatment the high efficiency needs

severe treatment conditions that would increase the cost ofSFE treatment In addition it would be also increase the costbecause of interaction of various variables Accordinglythese variables were taken into careful consideration byusing BoxndashBehnken design (BBD) with the soft of Design-Expert V806 in this study

e levels of each factor are given in Table 1 Twenty-seven experiments were carried out from the design (Ta-ble 2) e results of the second-order response surfacemodel fitting for extraction yield in the form of analysis ofvariance (ANOVA) are given in Table 3 To test the fit of themodel the regression equation and determination co-efficient R2 were evaluated e model presented a highdetermination coefficient (R2 0976) explaining 976 ofthe variability in the response (Table 3) e coefficients ofregression were calculated and the following regressionequation (4) was obtained

Table 3 presents Fisherrsquos F-test of ANOVA which alsoproves that this regression model was highly statisticallysignificant (Plt 00001) At the same time the relativelylower value of the coefficient of variation (CV 325 lt 10)indicates good precision and reliability of the experimentscarried out Adequate precision for our model has a signal-to-noise ratio of 18571 (gt4) which indicates an adequatesignal e signification of each coefficient was determinedby Tand Pwhich is also listed in Table 3 which demonstratesthat all the linear model terms (X3 and X4) and quadraticmodel term (X1X2 X2X4 and X3X4) were significantMoreover the interactive model terms X1X2 X2X4 andX3X4 were significant (Plt 005) while the interactive modelterms of X1X3 X1X4 and X2X3 were insignificant (Pgt 01)

2020

25

30

35

40Ex

trac

tion

yiel

d (

)

40 60 80 100 120 140 160Extraction time (min)

(a)

25

30

35

40

20 25 30 35 40Extraction temperature (degC)

Extr

actio

n yi

eld

()

(b)

8 12 16 20 24

24

28

32

36

Extr

actio

n yi

eld

()

CO2 flow (Lh)

(c)

Extr

actio

n yi

eld

()

10

40

35

30

2515 20 25 30

Extraction pressure (MPa)

(d)

25 30 35 40 45Separate pressure (MPa)

Extr

actio

n yi

eld

()

354

351

348

345

(e)

20 25 30 35 40Separate temperature (degC)

Extr

actio

n yi

eld

()

356

354

352

350

348

346

(f )

Figure 1 Influence of various parameters on SFE efficiency for essential oil

Journal of Analytical Methods in Chemistry 5

In addition the empirical model (Eq (1)) proved that thepredicted data of the response from the empirical model are inagreement with the observed ones in the range of the op-erating variables On the other hand the value of adjusted(R2 0948) is also very high that indicated a high significanceof the model e maximum extraction yield obtained byusing above selected variables was 436 and the experi-mental maximum obtained was 432 plusmn 006 e data showthat predicted data on the response from empirical modelwere in agreement with those observed in the range of theoperating variables e coefficients of regression were cal-culated and the following regression equation was obtained

Y 437 + 0014167X1 + 0006667X2 minus 0028333X3

minus 0035833X4 minus 005625X21 + 00425X1X2

minus 00275X1X3 + 00275X1X4 minus 00525X22

+ 00125X2X3 + 0045X2X4 minus 02975X23

+ 0045X3X4 minus 012875X24

(4)

where Y response (extraction yield) X1 extraction timeX2 extraction pressure X3 extraction temperature andX4 CO2 flow in coded values

In order to gain a better understanding of the effects ofthe variables on the essential oil of extraction yield from Ccitronella leaves the predicted model was presented as 3D2D response surface graphs as shown in Figure 2 re-spectively which were generated with one variable kept at itsoptimum level and varying the others within the experi-mental range (shown in Table 1) ese variables wereoptimized as follows extraction time 120min extractionpressure 25Mpa extraction temperature 35degC and CO2 flow18 Lh for the SFE process Under optimized condition theextracted essential oil reached 440 Nevertheless the resultis comparable to that reported elsewhere on extraction ofessential oil with various extraction methods indicating thatthe SFE had significantly higher extraction efficiency and

was the most energy-saving method than other methodscombining with an auxiliary instrument that could raise thecost of production [1 5 22ndash24] Consequently these resultshave suggested that the SFE treatment is effective for se-lectively extracting the essential oil from C citronella andmay be expected to use in others active componentsextracted from various plants in future

Recently many researchers argued the extraction yieldand essential oil compositions but paid little attention to theeffect of extraction methods on the essential oil composi-tions It would limit the development and application ofessential oils [5] Accordingly in the next experimentconstitute features of the extracted oil are characterized withmodern analytical equipment

33 Analysis of the Extracted Essential Oil e chemicalcompositions identified in the essential oils extracted by HDand SFE are summarized in Table 4 ere were 35 com-pounds identified in HD essential oils while 41 in SFE es-sential oils ese compositions were grouped into sevenclasses (hydrocarbons alcohols aldehydes esters ketonesalkanes and others) according to their functional groupsAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE e abundant al-cohols can promote the C citronella leaf essential oils usedfor cosmetic applicationse contents of flavourless alkanesin SFE oil were much lower than those of SFE (Table 4)indicating that the essential oil in SFE contains fewer im-purities which were similar to the previous report [8] emain component of essential oil extracted by SFE and HDwas geranialdehyde and the next was geraniol which wereconsistent with previous studies [23 25] Furthermore thecontent of this major compound in SFE extracts was higherthan HDis proved that supercritical fluid did not alter themain effective components in C citronella essential oil butthe content of effective composition and extraction yield ofessential oil was higher [8]

Table 3 ANOVA results for the quadratic equation for the extraction yield of essential oil

Term Freedom degrees Sum of squares Mean square F value Pr gt FModel 14 0564475 004032 3508174 lt00001X1 1 0002408 0002408 2095468 0173353X2 1 0000533 0000533 0464048 0508671X3 1 0009633 0009633 8381873 0013447X4 1 0015408 0015408 1340665 0003257X1 middot X1 1 0016875 0016875 1468278 0002388X1 middotX2 1 0007225 0007225 6286405 0027545X1 middotX3 1 0003025 0003025 2632024 0130689X1 middotX4 1 0003025 0003025 2632024 0130689X2 middotX2 1 00147 00147 1279033 0003808X2 middotX3 1 0000625 0000625 0543807 0475032X2 middotX4 1 00081 00081 7047734 0020994X3 middotX3 1 0472033 0472033 4107118 lt00001X3 middotX4 1 00081 00081 7047734 0020994X4 middotX4 1 0644342 0644342 7692326 lt00001Pure error 12 0013792 0001149 No clear No clear

R2 09761 Adj R2 09483 CV 325 Adeq precision 18571

6 Journal of Analytical Methods in Chemistry

34 Antioxidant Activity Analysis In this study antioxidantactivity of essential oil from the C citronella leaves wasevaluated using DPPH scavenging and 123-phentriol self-oxidation activity assays e IC50 values of essential oil aresummarized in Table 5 As reports 123-phentriol rapidlyautoxidizes in the autoxidized solution and several in-termediate products such as O2

minus were formed whichresulted in the solution to become yellow brown with aspectrum showing a shoulder between 400 and 425 nm eantioxidants could interfere with 123-phentriol autoxidationby acting as scavengers of O2

minus [11 12] erefore antioxidantability can be determined by the scavenging activity of self-oxidation of 123-phentriol Table 5 shows that both essentialoils extracted by SDE and SFE respectively had much moreeective scavenging power for self-oxidation of 123-phen-triol than BHTand ascorbic acid and it should be explored as apotential antioxidant with SFE process

Besides the model of scavenging the stable DPPH radicalis a widely used method of evaluating the free-radicalscavenging ability of natural compounds In the DPPHtest the antioxidants were able to reduce the stable DPPH

radical to the yellow-colored diphenylpicrylhydrazine eeect of antioxidants on DPPH radical scavenging wasthought to be due to their hydrogen-donating ability [12]e DPPH scavenging activity of the essential oils expressedin terms of IC50 is shown in Table 5 with the higher an-tioxidant potency of DPPH scavenging compared with theantioxidant potency of BHTand ascorbic acidereinto theessential oil extracted by SFE had the highest antioxidantpotency of DPPH scavenging

e antioxidant activities of antioxidants have been at-tributed to various mechanisms and one test is normally notenough to evaluate precisely the antioxidant activity of po-tential antioxidant [11]erefore we used these two assays toevaluate the total antioxidant capacity of essential oil from theC citronella leaves e results indicated that the essential oilhad a noticeable eect on scavenging self-oxidation of 123-phentriol and were able to scavenge free radicals

35 Antimicrobial Activity Analysis e antimicrobial ac-tivities of extracts gained from HD and SFE had been

Extraction temperature (degC)CO

2 flow (Lh)

Extr

actio

n yi

eld

()

45

44

43

42

41

40

39

38

37

36

1212

100806

040200

ndash02ndash04

ndash06ndash08

ndash10ndash12

1008

0604

0200

ndash02ndash04

ndash06ndash08

ndash10ndash12

(a)

44

43

42

41

39

40

Extraction pressure (Lh) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(b)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction pressure (Lh)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06ndash08

ndash10ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(c)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(d)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction time (min)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(e)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction pressure (Lh)

Extr

actio

n yi

eld

()

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(f )

Figure 2 Response surface plot (3D and 2D) for the interactive eect of variables (a) Eect of CO2 ow and extraction temperature withxed extraction time and extraction pressure at 120min and 25Mpa respectively (b) eect of extraction time and extraction pressure withxed CO2 ow and extraction temperature at 18 Lh and 35degC respectively (c) eect of CO2 ow and extraction pressure with xedextraction time and extraction temperature at 120min and 35degC respectively (d) eect of extraction time and extraction temperature withxed CO2 ow and extraction pressure at 18 Lh and 25MPa respectively (e) eect of CO2 ow and extraction time with xed extractiontemperature and extraction pressure at 35degC and 25MPa respectively (f ) eect of extraction temperature and extraction pressure with xedCO2 ow and extraction time at 18 Lh and 120min respectively

Journal of Analytical Methods in Chemistry 7

Table 4 Chemical compositions of essential oils

No ComponentsConcentration of essential oil ()

HD SFE1 α-Pinene 071 0672 β-Pinene 431 6003 D-Limonene 02 3554 β-Ocimene ND 0155 8-Methyl 1-hendecene ND 0186 α-Guaiene 025 0457 β-Caryophyllene 246 018 α-Bergamotene ND ND9 3-Carene 046 ND10 α-Cubebene 094 04611 α-Muurolene 026 0312 c-Muurolene 167 0213 α-Copaene 129 11314 β-Bourbonene 197 ND15 β-Guaiene 014 ND

Hydrocarbons 1466 131916 Hinesol 091 2817 2-Borneol ND 07618 Isopulegol 035 01819 trans-Verbenol ND 03320 cis-Verbenol 046 09521 Nerol 035 01922 Geraniol 939 64323 trans-Farnesol ND 13424 Geraniol 2545 102225 trans-Geranylgeraniol 04 13126 3-Methyl cyclohexanol 071 20127 cis-Geranylgeraniol 035 ND28 Globulol 137 05529 c-Eucalyptol ND 08030 Carotol 037 ND31 α-Cadinol 025 14732 Cubenol 055 341

Alcohols 4091 327533 Citronellal 1277 125734 Lauraldehyde 03 01335 Neral 1115 151136 Geranialdehyde 1512 2002

Aldehydes 3934 478337 Citronellyl acetate ND 02338 Citronellyl isobutyrate 061 12739 Geraniol acetate 224 065

Esters 285 21540 D-Carvone ND 01541 D-Verbenone ND 030

Ketones 0 04542 Hexadecane 019 ND43 Dioctylmethane ND 040

Alkanes 019 04044 Rose oxide ND 01045 Geranic acid ND 01446 Eugenol 017 03347 2-Epoxy-trans-p-menthane ND 03948 Caryophyllene oxide 157 04149 3-Decyne 019 ND

Others 174 137Total identified 9969 9814ND not detected

8 Journal of Analytical Methods in Chemistry

assessed using a serial twofold dilution assay and paper discdiffusion assay according to Hu et al [23 24 26] Table 6shows the variation in the antimicrobial properties of theessential oil extracted from the C citronella leaves Amongbacterial strains the E coli has the strongest inhibitory effectby the essential oil Meanwhile the essential oil shows theantifungal or anticandidal activity as well On the otherhand more precise data concerning the antimicrobialproperties of the extracts were obtained by paper disc dif-fusion assay [26] Table 6 indicates the maximal inhibitoryzones for each of the microorganisms that were sensitive tothe extracts which were in the range of 15ndash35mmereinto the greater inhibition was observed in the case ofthe SFE extracts than the others Hence the SFE extracts wassignificant antimicrobial or antifungal activities against all ofthe microorganisms tested except A niger

In summary the SFE extracts have significant antimi-crobial activity against E coli and A niger respectivelyAntimicrobial activity in essential oil depended on mostlyaldehydes and acid esters [22 27] Recently some literaturereported there was the highest level of activity against E coliwith tea oil tannic acid and saponins [6 20 23] Ac-cordingly these observations suggested that the antimi-crobial activity of essential oil may be due to the presence ofester bond and ether bond [28] Other phenolic acid-likephenols were also thought to contribute to plant defensesagainst pests and pathogens [11]

4 Conclusions

e essential oil was attained from C citronella a commonherbaceous plant by supercritical fluid extraction resultingin 440 of essential oil extracted under mild conditionAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE Compared with HDessential oils the SFE essential oils contain fewer impuritiesand had better antioxidant and antimicrobial activitiesSupercritical fluid extraction has presented an outstandingfeature in efficient extraction of active components of the

plant which can be a desirable candidate for the currentextraction processing

Data Availability

e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was funded by the Project of Key Technologies ofHigh-Yield and Carbon Dioxide Emissions in the Full Uti-lization Process of Industrial Oil Plants (2017WK2021)National Sci-Tech Support Plan (2015BAD15B02) and Hu-nan Key Science and Technology Program (2016NK1001)

References

[1] R Pavela ldquoEssential oils for the development of eco-friendlymosquito larvicides a reviewrdquo Industrial Crops and Productsvol 76 no 4 pp 174ndash187 2015

[2] S R Sargenti and F M Lanccedilas ldquoSupercritical fluid extractionof Cymbopogon citratus (DC) Stapfrdquo Chromatographiavol 46 no 5-6 pp 285ndash290 1997

[3] V Sriramavaratharajan J Stephan V Sudha andR Murugan ldquoLeaf essential oil of Cinnamomum agasthya-malayanum from the Western Ghats India-A new source ofcamphorrdquo Industrial Crops and Products vol 86 pp 259ndash2612016

[4] R Pavela E Stepanycheva A Shchenikova T Chermenskayaand M Petrova ldquoEssential oils as prospective fumigants againstTetranychus urticae Kochrdquo Industrial Crops and Productsvol 94 pp 755ndash761 2016

[5] J R Calo P G Crandall C A OrsquoBryan and S C RickeldquoEssential oils as antimicrobials in food systems-a reviewrdquoFood Control vol 54 pp 111ndash119 2015

Table 5 Half-inhibition (IC50) values of antioxidant activities measured using DPPH radical scavenging and 123-phentriol self-oxidation

SamplesIC50 (mgg)

123-Phentriol self-oxidation DPPHSDE 274 plusmn 2 10 plusmn 1SFE 244 plusmn 3 9 plusmn 2AAlowast 5137 plusmn 4 2213 plusmn 4BHTlowast 8029 plusmn 1 895 plusmn 3lowastControl

Table 6 Minimal inhibitory concentration (MIC) of the essential oils with various extraction processes

Immature stagesInhibition zones (mm) MIC (mgmL)

S aureus E coli A niger A fumigatus S aureus E coli A niger A fumigatusSFE 178 plusmn 12 252 plusmn 09 141 plusmn 10 331 plusmn 13 56 plusmn 02 14 plusmn 01 28 plusmn 02 56 plusmn 0SDE 142 plusmn 11 196 plusmn 12 231 plusmn 11 243 plusmn 13 56 plusmn 01 28 plusmn 02 14 plusmn 01 28 plusmn 02Citrallowast 222 plusmn 06 187 plusmn 10 195 plusmn 34 146 plusmn 23 112 plusmn 05 112 plusmn 03 56 plusmn 01 112 plusmn 01lowastControl

Journal of Analytical Methods in Chemistry 9

[6] S Patel and P Gogna ldquoTapping botanicals for essential oilsprogress and hurdles in cancer mitigationrdquo Industrial Cropsand Products vol 76 pp 1148ndash1163 2015

[7] H G Huang Y E Xiao L Q Tian et al ldquoComparative studyon supercritical fluid extraction and steam distillation inextracting chemical constituents and relative contents ofvolatile oil from compatibility of Ramulus cinnamomi andRhizoma zingiberisrdquo Journal of Experimental TraditionalMedical Formulae (Chinese) vol 17 pp 85ndash92 2011

[8] R H Olmedo C M Asensio and N R Grosso ldquoermalstability and antioxidant activity of essential oils from aro-matic plants farmed in Argentinardquo Industrial Crops andProducts vol 69 no 6 pp 21ndash28 2015

[9] E Arranz L Jaime M C Lopez de las Hazas G Reglero andS Santoyo ldquoSupercritical fluid extraction as an alternativeprocess to obtain essential oils with anti-inflammatoryproperties from marjoram and sweet basilrdquo IndustrialCrops and Products vol 67 pp 121ndash129 2015

[10] A Berna A Tarrega M Blasco and S Subirats ldquoSupercriticalCO2 extraction of essential oil from orange peel effect of theheight of the bedrdquo Journal of Supercritical Fluids vol 18 no 3pp 227ndash237 2000

[11] M T Baratta H J D Dorman S G Deans A C FigueiredoJ G Barroso and G Ruberto ldquoAntimicrobial and antioxidantproperties of some commercial essential oilsrdquo Flavour andFragrance Journal vol 13 no 4 pp 235ndash244 2015

[12] H J D Dorman A C Figueiredo J G Barroso andS G Deans ldquoIn vitro evaluation of antioxidant activity ofessential oils and their componentsrdquo Flavour and FragranceJournal vol 15 no 1 pp 12ndash16 2015

[13] C Y Niu F Q Zhang D M Diao and F U Yan ldquoExtractionconditions optimization of essential oil from steamed ginsengwater by response surface methodology and GC-MS analysisrdquoScience and Technology of Food Industry (Chinese) vol 35no 18 pp 310ndash309 2014

[14] M L Harkat B Asma K Madani et al ldquoChemical com-position antibacterial and antioxidant activities of essentialoil of Eucalyptus globulus from Algeriardquo Industrial Crops andProducts vol 78 pp 148ndash153 2015

[15] H Y Kil E S Seong B K Ghimire et al ldquoAntioxidant andantimicrobial activities of crude sorghum extractrdquo FoodChemistry vol 115 no 4 pp 1234ndash1239 2009

[16] J Rakmai B Cheirsilp A Torrado-Agrasar J Simal-Gandaraand J C Mejuto ldquoEncapsulation of yarrow essential oil inhydroxypropyl-beta-cyclodextrin physiochemical character-ization and evaluation of bio-efficaciesrdquo CyTA-Journal ofFood vol 15 no 3 pp 409ndash417 2017

[17] J Rakmai B Cheirsilp J C Mejuto J Simal-Gandara andA Torrado-Agrasar ldquoAntioxidant and antimicrobial prop-erties of encapsulated guava leaf oil in hydroxypropyl-beta-cyclodextrinrdquo Industrial Crops and Products vol 111pp 219ndash225 2018

[18] J Rakmai B Cheirsilp J C Mejuto A Torrado-Agrasar andJ Simal-Gandara ldquoPhysico-chemical characterization andevaluation of bio-efficacies of black pepper essential oil en-capsulated in hydroxypropyl-beta-cyclodextrinrdquo Food Hy-drocolloids vol 65 pp 157ndash164 2016

[19] L H C Carlson R A F Machado C B SpricigoL K Pereira and A Bolzan ldquoExtraction of lemongrass es-sential oil with dense carbon dioxiderdquo Journal of SupercriticalFluids vol 21 no 1 pp 33ndash39 2001

[20] Q Qiu J LIing Y Ding H Chang J Wang and T LiuldquoComparison of supercritical fluid extraction and steamdistillation methods for the extraction of essential oils from

Schizonepeta tenuifolia briqrdquo Chromatography vol 23 no 6pp 646ndash650 2005

[21] G Sodeifian S A Sajadian and N Saadati Ardestani ldquoEx-perimental optimization and mathematical modeling of thesupercritical fluid extraction of essential oil from Eryngiumbillardieri application of simulated annealing (SA) algo-rithmrdquo Journal of Supercritical Fluids vol 127 pp 146ndash1572017

[22] A Gasparetto A Bella Cruz T M Wagner T J BonominiR Correa and A Malheiros ldquoSeasonal variation in thechemical composition antimicrobial and mutagenic potentialof essential oils from Piper cernuumrdquo Industrial Crops andProducts vol 95 pp 256ndash263 2017

[23] E Konoz N Hajikhani and A Abbasi ldquoComparison of twomethods for extraction of dill essential oil by gaschromatography-mass spectrometry coupled with chemo-metric resolution techniquesrdquo International Journal of FoodProperties vol 20 no 1 pp S1002ndashS1015 2017

[24] H J Zhang Y B Cao W B Xue H Ding G F Liu andJ Q Wang ldquoOptimization of extraction process of citronellaessential oil and its gas phase antibacterial propertiesrdquo ChinaCondiment vol 42 pp 15ndash20 2017

[25] M D Guillen N Cabo and J Burillo ldquoCharacterisation ofthe essential oils of some cultivated aromatic plants of in-dustrial interestrdquo Journal of the Science of Food and Agri-culture vol 70 no 3 pp 359ndash363 1996

[26] J Hu S Nie D Huang C Li and M Xie ldquoExtraction ofsaponin from camellia oleifera cake and evaluation of itsantioxidant activityrdquo International Journal of Food Scienceand Technology vol 47 no 8 pp 1676ndash1687 2012

[27] J Singh and N N Tripathi ldquoInhibition of storage fungi ofblackgram (Vigna mungo L) by some essential oilsrdquo Flavourand Fragrance Journal vol 14 no 1 pp 1ndash4 2015

[28] P Matusinsky M Zouhar R Pavela and P Novy ldquoAnti-fungal effect of five essential oils against important pathogenicfungi of cerealsrdquo Industrial Crops and Products vol 67pp 208ndash215 2015

10 Journal of Analytical Methods in Chemistry

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Advances inPhysical Chemistry

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Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of

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Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

In addition the empirical model (Eq (1)) proved that thepredicted data of the response from the empirical model are inagreement with the observed ones in the range of the op-erating variables On the other hand the value of adjusted(R2 0948) is also very high that indicated a high significanceof the model e maximum extraction yield obtained byusing above selected variables was 436 and the experi-mental maximum obtained was 432 plusmn 006 e data showthat predicted data on the response from empirical modelwere in agreement with those observed in the range of theoperating variables e coefficients of regression were cal-culated and the following regression equation was obtained

Y 437 + 0014167X1 + 0006667X2 minus 0028333X3

minus 0035833X4 minus 005625X21 + 00425X1X2

minus 00275X1X3 + 00275X1X4 minus 00525X22

+ 00125X2X3 + 0045X2X4 minus 02975X23

+ 0045X3X4 minus 012875X24

(4)

where Y response (extraction yield) X1 extraction timeX2 extraction pressure X3 extraction temperature andX4 CO2 flow in coded values

In order to gain a better understanding of the effects ofthe variables on the essential oil of extraction yield from Ccitronella leaves the predicted model was presented as 3D2D response surface graphs as shown in Figure 2 re-spectively which were generated with one variable kept at itsoptimum level and varying the others within the experi-mental range (shown in Table 1) ese variables wereoptimized as follows extraction time 120min extractionpressure 25Mpa extraction temperature 35degC and CO2 flow18 Lh for the SFE process Under optimized condition theextracted essential oil reached 440 Nevertheless the resultis comparable to that reported elsewhere on extraction ofessential oil with various extraction methods indicating thatthe SFE had significantly higher extraction efficiency and

was the most energy-saving method than other methodscombining with an auxiliary instrument that could raise thecost of production [1 5 22ndash24] Consequently these resultshave suggested that the SFE treatment is effective for se-lectively extracting the essential oil from C citronella andmay be expected to use in others active componentsextracted from various plants in future

Recently many researchers argued the extraction yieldand essential oil compositions but paid little attention to theeffect of extraction methods on the essential oil composi-tions It would limit the development and application ofessential oils [5] Accordingly in the next experimentconstitute features of the extracted oil are characterized withmodern analytical equipment

33 Analysis of the Extracted Essential Oil e chemicalcompositions identified in the essential oils extracted by HDand SFE are summarized in Table 4 ere were 35 com-pounds identified in HD essential oils while 41 in SFE es-sential oils ese compositions were grouped into sevenclasses (hydrocarbons alcohols aldehydes esters ketonesalkanes and others) according to their functional groupsAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE e abundant al-cohols can promote the C citronella leaf essential oils usedfor cosmetic applicationse contents of flavourless alkanesin SFE oil were much lower than those of SFE (Table 4)indicating that the essential oil in SFE contains fewer im-purities which were similar to the previous report [8] emain component of essential oil extracted by SFE and HDwas geranialdehyde and the next was geraniol which wereconsistent with previous studies [23 25] Furthermore thecontent of this major compound in SFE extracts was higherthan HDis proved that supercritical fluid did not alter themain effective components in C citronella essential oil butthe content of effective composition and extraction yield ofessential oil was higher [8]

Table 3 ANOVA results for the quadratic equation for the extraction yield of essential oil

Term Freedom degrees Sum of squares Mean square F value Pr gt FModel 14 0564475 004032 3508174 lt00001X1 1 0002408 0002408 2095468 0173353X2 1 0000533 0000533 0464048 0508671X3 1 0009633 0009633 8381873 0013447X4 1 0015408 0015408 1340665 0003257X1 middot X1 1 0016875 0016875 1468278 0002388X1 middotX2 1 0007225 0007225 6286405 0027545X1 middotX3 1 0003025 0003025 2632024 0130689X1 middotX4 1 0003025 0003025 2632024 0130689X2 middotX2 1 00147 00147 1279033 0003808X2 middotX3 1 0000625 0000625 0543807 0475032X2 middotX4 1 00081 00081 7047734 0020994X3 middotX3 1 0472033 0472033 4107118 lt00001X3 middotX4 1 00081 00081 7047734 0020994X4 middotX4 1 0644342 0644342 7692326 lt00001Pure error 12 0013792 0001149 No clear No clear

R2 09761 Adj R2 09483 CV 325 Adeq precision 18571

6 Journal of Analytical Methods in Chemistry

34 Antioxidant Activity Analysis In this study antioxidantactivity of essential oil from the C citronella leaves wasevaluated using DPPH scavenging and 123-phentriol self-oxidation activity assays e IC50 values of essential oil aresummarized in Table 5 As reports 123-phentriol rapidlyautoxidizes in the autoxidized solution and several in-termediate products such as O2

minus were formed whichresulted in the solution to become yellow brown with aspectrum showing a shoulder between 400 and 425 nm eantioxidants could interfere with 123-phentriol autoxidationby acting as scavengers of O2

minus [11 12] erefore antioxidantability can be determined by the scavenging activity of self-oxidation of 123-phentriol Table 5 shows that both essentialoils extracted by SDE and SFE respectively had much moreeective scavenging power for self-oxidation of 123-phen-triol than BHTand ascorbic acid and it should be explored as apotential antioxidant with SFE process

Besides the model of scavenging the stable DPPH radicalis a widely used method of evaluating the free-radicalscavenging ability of natural compounds In the DPPHtest the antioxidants were able to reduce the stable DPPH

radical to the yellow-colored diphenylpicrylhydrazine eeect of antioxidants on DPPH radical scavenging wasthought to be due to their hydrogen-donating ability [12]e DPPH scavenging activity of the essential oils expressedin terms of IC50 is shown in Table 5 with the higher an-tioxidant potency of DPPH scavenging compared with theantioxidant potency of BHTand ascorbic acidereinto theessential oil extracted by SFE had the highest antioxidantpotency of DPPH scavenging

e antioxidant activities of antioxidants have been at-tributed to various mechanisms and one test is normally notenough to evaluate precisely the antioxidant activity of po-tential antioxidant [11]erefore we used these two assays toevaluate the total antioxidant capacity of essential oil from theC citronella leaves e results indicated that the essential oilhad a noticeable eect on scavenging self-oxidation of 123-phentriol and were able to scavenge free radicals

35 Antimicrobial Activity Analysis e antimicrobial ac-tivities of extracts gained from HD and SFE had been

Extraction temperature (degC)CO

2 flow (Lh)

Extr

actio

n yi

eld

()

45

44

43

42

41

40

39

38

37

36

1212

100806

040200

ndash02ndash04

ndash06ndash08

ndash10ndash12

1008

0604

0200

ndash02ndash04

ndash06ndash08

ndash10ndash12

(a)

44

43

42

41

39

40

Extraction pressure (Lh) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(b)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction pressure (Lh)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06ndash08

ndash10ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(c)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(d)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction time (min)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(e)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction pressure (Lh)

Extr

actio

n yi

eld

()

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(f )

Figure 2 Response surface plot (3D and 2D) for the interactive eect of variables (a) Eect of CO2 ow and extraction temperature withxed extraction time and extraction pressure at 120min and 25Mpa respectively (b) eect of extraction time and extraction pressure withxed CO2 ow and extraction temperature at 18 Lh and 35degC respectively (c) eect of CO2 ow and extraction pressure with xedextraction time and extraction temperature at 120min and 35degC respectively (d) eect of extraction time and extraction temperature withxed CO2 ow and extraction pressure at 18 Lh and 25MPa respectively (e) eect of CO2 ow and extraction time with xed extractiontemperature and extraction pressure at 35degC and 25MPa respectively (f ) eect of extraction temperature and extraction pressure with xedCO2 ow and extraction time at 18 Lh and 120min respectively

Journal of Analytical Methods in Chemistry 7

Table 4 Chemical compositions of essential oils

No ComponentsConcentration of essential oil ()

HD SFE1 α-Pinene 071 0672 β-Pinene 431 6003 D-Limonene 02 3554 β-Ocimene ND 0155 8-Methyl 1-hendecene ND 0186 α-Guaiene 025 0457 β-Caryophyllene 246 018 α-Bergamotene ND ND9 3-Carene 046 ND10 α-Cubebene 094 04611 α-Muurolene 026 0312 c-Muurolene 167 0213 α-Copaene 129 11314 β-Bourbonene 197 ND15 β-Guaiene 014 ND

Hydrocarbons 1466 131916 Hinesol 091 2817 2-Borneol ND 07618 Isopulegol 035 01819 trans-Verbenol ND 03320 cis-Verbenol 046 09521 Nerol 035 01922 Geraniol 939 64323 trans-Farnesol ND 13424 Geraniol 2545 102225 trans-Geranylgeraniol 04 13126 3-Methyl cyclohexanol 071 20127 cis-Geranylgeraniol 035 ND28 Globulol 137 05529 c-Eucalyptol ND 08030 Carotol 037 ND31 α-Cadinol 025 14732 Cubenol 055 341

Alcohols 4091 327533 Citronellal 1277 125734 Lauraldehyde 03 01335 Neral 1115 151136 Geranialdehyde 1512 2002

Aldehydes 3934 478337 Citronellyl acetate ND 02338 Citronellyl isobutyrate 061 12739 Geraniol acetate 224 065

Esters 285 21540 D-Carvone ND 01541 D-Verbenone ND 030

Ketones 0 04542 Hexadecane 019 ND43 Dioctylmethane ND 040

Alkanes 019 04044 Rose oxide ND 01045 Geranic acid ND 01446 Eugenol 017 03347 2-Epoxy-trans-p-menthane ND 03948 Caryophyllene oxide 157 04149 3-Decyne 019 ND

Others 174 137Total identified 9969 9814ND not detected

8 Journal of Analytical Methods in Chemistry

assessed using a serial twofold dilution assay and paper discdiffusion assay according to Hu et al [23 24 26] Table 6shows the variation in the antimicrobial properties of theessential oil extracted from the C citronella leaves Amongbacterial strains the E coli has the strongest inhibitory effectby the essential oil Meanwhile the essential oil shows theantifungal or anticandidal activity as well On the otherhand more precise data concerning the antimicrobialproperties of the extracts were obtained by paper disc dif-fusion assay [26] Table 6 indicates the maximal inhibitoryzones for each of the microorganisms that were sensitive tothe extracts which were in the range of 15ndash35mmereinto the greater inhibition was observed in the case ofthe SFE extracts than the others Hence the SFE extracts wassignificant antimicrobial or antifungal activities against all ofthe microorganisms tested except A niger

In summary the SFE extracts have significant antimi-crobial activity against E coli and A niger respectivelyAntimicrobial activity in essential oil depended on mostlyaldehydes and acid esters [22 27] Recently some literaturereported there was the highest level of activity against E coliwith tea oil tannic acid and saponins [6 20 23] Ac-cordingly these observations suggested that the antimi-crobial activity of essential oil may be due to the presence ofester bond and ether bond [28] Other phenolic acid-likephenols were also thought to contribute to plant defensesagainst pests and pathogens [11]

4 Conclusions

e essential oil was attained from C citronella a commonherbaceous plant by supercritical fluid extraction resultingin 440 of essential oil extracted under mild conditionAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE Compared with HDessential oils the SFE essential oils contain fewer impuritiesand had better antioxidant and antimicrobial activitiesSupercritical fluid extraction has presented an outstandingfeature in efficient extraction of active components of the

plant which can be a desirable candidate for the currentextraction processing

Data Availability

e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was funded by the Project of Key Technologies ofHigh-Yield and Carbon Dioxide Emissions in the Full Uti-lization Process of Industrial Oil Plants (2017WK2021)National Sci-Tech Support Plan (2015BAD15B02) and Hu-nan Key Science and Technology Program (2016NK1001)

References

[1] R Pavela ldquoEssential oils for the development of eco-friendlymosquito larvicides a reviewrdquo Industrial Crops and Productsvol 76 no 4 pp 174ndash187 2015

[2] S R Sargenti and F M Lanccedilas ldquoSupercritical fluid extractionof Cymbopogon citratus (DC) Stapfrdquo Chromatographiavol 46 no 5-6 pp 285ndash290 1997

[3] V Sriramavaratharajan J Stephan V Sudha andR Murugan ldquoLeaf essential oil of Cinnamomum agasthya-malayanum from the Western Ghats India-A new source ofcamphorrdquo Industrial Crops and Products vol 86 pp 259ndash2612016

[4] R Pavela E Stepanycheva A Shchenikova T Chermenskayaand M Petrova ldquoEssential oils as prospective fumigants againstTetranychus urticae Kochrdquo Industrial Crops and Productsvol 94 pp 755ndash761 2016

[5] J R Calo P G Crandall C A OrsquoBryan and S C RickeldquoEssential oils as antimicrobials in food systems-a reviewrdquoFood Control vol 54 pp 111ndash119 2015

Table 5 Half-inhibition (IC50) values of antioxidant activities measured using DPPH radical scavenging and 123-phentriol self-oxidation

SamplesIC50 (mgg)

123-Phentriol self-oxidation DPPHSDE 274 plusmn 2 10 plusmn 1SFE 244 plusmn 3 9 plusmn 2AAlowast 5137 plusmn 4 2213 plusmn 4BHTlowast 8029 plusmn 1 895 plusmn 3lowastControl

Table 6 Minimal inhibitory concentration (MIC) of the essential oils with various extraction processes

Immature stagesInhibition zones (mm) MIC (mgmL)

S aureus E coli A niger A fumigatus S aureus E coli A niger A fumigatusSFE 178 plusmn 12 252 plusmn 09 141 plusmn 10 331 plusmn 13 56 plusmn 02 14 plusmn 01 28 plusmn 02 56 plusmn 0SDE 142 plusmn 11 196 plusmn 12 231 plusmn 11 243 plusmn 13 56 plusmn 01 28 plusmn 02 14 plusmn 01 28 plusmn 02Citrallowast 222 plusmn 06 187 plusmn 10 195 plusmn 34 146 plusmn 23 112 plusmn 05 112 plusmn 03 56 plusmn 01 112 plusmn 01lowastControl

Journal of Analytical Methods in Chemistry 9

[6] S Patel and P Gogna ldquoTapping botanicals for essential oilsprogress and hurdles in cancer mitigationrdquo Industrial Cropsand Products vol 76 pp 1148ndash1163 2015

[7] H G Huang Y E Xiao L Q Tian et al ldquoComparative studyon supercritical fluid extraction and steam distillation inextracting chemical constituents and relative contents ofvolatile oil from compatibility of Ramulus cinnamomi andRhizoma zingiberisrdquo Journal of Experimental TraditionalMedical Formulae (Chinese) vol 17 pp 85ndash92 2011

[8] R H Olmedo C M Asensio and N R Grosso ldquoermalstability and antioxidant activity of essential oils from aro-matic plants farmed in Argentinardquo Industrial Crops andProducts vol 69 no 6 pp 21ndash28 2015

[9] E Arranz L Jaime M C Lopez de las Hazas G Reglero andS Santoyo ldquoSupercritical fluid extraction as an alternativeprocess to obtain essential oils with anti-inflammatoryproperties from marjoram and sweet basilrdquo IndustrialCrops and Products vol 67 pp 121ndash129 2015

[10] A Berna A Tarrega M Blasco and S Subirats ldquoSupercriticalCO2 extraction of essential oil from orange peel effect of theheight of the bedrdquo Journal of Supercritical Fluids vol 18 no 3pp 227ndash237 2000

[11] M T Baratta H J D Dorman S G Deans A C FigueiredoJ G Barroso and G Ruberto ldquoAntimicrobial and antioxidantproperties of some commercial essential oilsrdquo Flavour andFragrance Journal vol 13 no 4 pp 235ndash244 2015

[12] H J D Dorman A C Figueiredo J G Barroso andS G Deans ldquoIn vitro evaluation of antioxidant activity ofessential oils and their componentsrdquo Flavour and FragranceJournal vol 15 no 1 pp 12ndash16 2015

[13] C Y Niu F Q Zhang D M Diao and F U Yan ldquoExtractionconditions optimization of essential oil from steamed ginsengwater by response surface methodology and GC-MS analysisrdquoScience and Technology of Food Industry (Chinese) vol 35no 18 pp 310ndash309 2014

[14] M L Harkat B Asma K Madani et al ldquoChemical com-position antibacterial and antioxidant activities of essentialoil of Eucalyptus globulus from Algeriardquo Industrial Crops andProducts vol 78 pp 148ndash153 2015

[15] H Y Kil E S Seong B K Ghimire et al ldquoAntioxidant andantimicrobial activities of crude sorghum extractrdquo FoodChemistry vol 115 no 4 pp 1234ndash1239 2009

[16] J Rakmai B Cheirsilp A Torrado-Agrasar J Simal-Gandaraand J C Mejuto ldquoEncapsulation of yarrow essential oil inhydroxypropyl-beta-cyclodextrin physiochemical character-ization and evaluation of bio-efficaciesrdquo CyTA-Journal ofFood vol 15 no 3 pp 409ndash417 2017

[17] J Rakmai B Cheirsilp J C Mejuto J Simal-Gandara andA Torrado-Agrasar ldquoAntioxidant and antimicrobial prop-erties of encapsulated guava leaf oil in hydroxypropyl-beta-cyclodextrinrdquo Industrial Crops and Products vol 111pp 219ndash225 2018

[18] J Rakmai B Cheirsilp J C Mejuto A Torrado-Agrasar andJ Simal-Gandara ldquoPhysico-chemical characterization andevaluation of bio-efficacies of black pepper essential oil en-capsulated in hydroxypropyl-beta-cyclodextrinrdquo Food Hy-drocolloids vol 65 pp 157ndash164 2016

[19] L H C Carlson R A F Machado C B SpricigoL K Pereira and A Bolzan ldquoExtraction of lemongrass es-sential oil with dense carbon dioxiderdquo Journal of SupercriticalFluids vol 21 no 1 pp 33ndash39 2001

[20] Q Qiu J LIing Y Ding H Chang J Wang and T LiuldquoComparison of supercritical fluid extraction and steamdistillation methods for the extraction of essential oils from

Schizonepeta tenuifolia briqrdquo Chromatography vol 23 no 6pp 646ndash650 2005

[21] G Sodeifian S A Sajadian and N Saadati Ardestani ldquoEx-perimental optimization and mathematical modeling of thesupercritical fluid extraction of essential oil from Eryngiumbillardieri application of simulated annealing (SA) algo-rithmrdquo Journal of Supercritical Fluids vol 127 pp 146ndash1572017

[22] A Gasparetto A Bella Cruz T M Wagner T J BonominiR Correa and A Malheiros ldquoSeasonal variation in thechemical composition antimicrobial and mutagenic potentialof essential oils from Piper cernuumrdquo Industrial Crops andProducts vol 95 pp 256ndash263 2017

[23] E Konoz N Hajikhani and A Abbasi ldquoComparison of twomethods for extraction of dill essential oil by gaschromatography-mass spectrometry coupled with chemo-metric resolution techniquesrdquo International Journal of FoodProperties vol 20 no 1 pp S1002ndashS1015 2017

[24] H J Zhang Y B Cao W B Xue H Ding G F Liu andJ Q Wang ldquoOptimization of extraction process of citronellaessential oil and its gas phase antibacterial propertiesrdquo ChinaCondiment vol 42 pp 15ndash20 2017

[25] M D Guillen N Cabo and J Burillo ldquoCharacterisation ofthe essential oils of some cultivated aromatic plants of in-dustrial interestrdquo Journal of the Science of Food and Agri-culture vol 70 no 3 pp 359ndash363 1996

[26] J Hu S Nie D Huang C Li and M Xie ldquoExtraction ofsaponin from camellia oleifera cake and evaluation of itsantioxidant activityrdquo International Journal of Food Scienceand Technology vol 47 no 8 pp 1676ndash1687 2012

[27] J Singh and N N Tripathi ldquoInhibition of storage fungi ofblackgram (Vigna mungo L) by some essential oilsrdquo Flavourand Fragrance Journal vol 14 no 1 pp 1ndash4 2015

[28] P Matusinsky M Zouhar R Pavela and P Novy ldquoAnti-fungal effect of five essential oils against important pathogenicfungi of cerealsrdquo Industrial Crops and Products vol 67pp 208ndash215 2015

10 Journal of Analytical Methods in Chemistry

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

International Journal ofInternational Journal ofPhotoenergy

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Biochemistry Research International

Hindawiwwwhindawicom Volume 2018

Enzyme Research

Hindawiwwwhindawicom Volume 2018

Journal of

SpectroscopyAnalytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

MaterialsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

BioMed Research International Electrochemistry

International Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

34 Antioxidant Activity Analysis In this study antioxidantactivity of essential oil from the C citronella leaves wasevaluated using DPPH scavenging and 123-phentriol self-oxidation activity assays e IC50 values of essential oil aresummarized in Table 5 As reports 123-phentriol rapidlyautoxidizes in the autoxidized solution and several in-termediate products such as O2

minus were formed whichresulted in the solution to become yellow brown with aspectrum showing a shoulder between 400 and 425 nm eantioxidants could interfere with 123-phentriol autoxidationby acting as scavengers of O2

minus [11 12] erefore antioxidantability can be determined by the scavenging activity of self-oxidation of 123-phentriol Table 5 shows that both essentialoils extracted by SDE and SFE respectively had much moreeective scavenging power for self-oxidation of 123-phen-triol than BHTand ascorbic acid and it should be explored as apotential antioxidant with SFE process

Besides the model of scavenging the stable DPPH radicalis a widely used method of evaluating the free-radicalscavenging ability of natural compounds In the DPPHtest the antioxidants were able to reduce the stable DPPH

radical to the yellow-colored diphenylpicrylhydrazine eeect of antioxidants on DPPH radical scavenging wasthought to be due to their hydrogen-donating ability [12]e DPPH scavenging activity of the essential oils expressedin terms of IC50 is shown in Table 5 with the higher an-tioxidant potency of DPPH scavenging compared with theantioxidant potency of BHTand ascorbic acidereinto theessential oil extracted by SFE had the highest antioxidantpotency of DPPH scavenging

e antioxidant activities of antioxidants have been at-tributed to various mechanisms and one test is normally notenough to evaluate precisely the antioxidant activity of po-tential antioxidant [11]erefore we used these two assays toevaluate the total antioxidant capacity of essential oil from theC citronella leaves e results indicated that the essential oilhad a noticeable eect on scavenging self-oxidation of 123-phentriol and were able to scavenge free radicals

35 Antimicrobial Activity Analysis e antimicrobial ac-tivities of extracts gained from HD and SFE had been

Extraction temperature (degC)CO

2 flow (Lh)

Extr

actio

n yi

eld

()

45

44

43

42

41

40

39

38

37

36

1212

100806

040200

ndash02ndash04

ndash06ndash08

ndash10ndash12

1008

0604

0200

ndash02ndash04

ndash06ndash08

ndash10ndash12

(a)

44

43

42

41

39

40

Extraction pressure (Lh) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(b)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction pressure (Lh)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06ndash08

ndash10ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(c)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction time (m

in)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(d)

44

43

42

41

39

40

CO2 flow (Lh)

Extraction time (min)

Extr

actio

n yi

eld

()

121008

060402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(e)

44

43

42

41

39

38

37

40

Extraction temperature (degC) Extraction pressure (Lh)

Extr

actio

n yi

eld

()

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

1210

0806

0402

00ndash02

ndash04ndash06

ndash08ndash10

ndash12

(f )

Figure 2 Response surface plot (3D and 2D) for the interactive eect of variables (a) Eect of CO2 ow and extraction temperature withxed extraction time and extraction pressure at 120min and 25Mpa respectively (b) eect of extraction time and extraction pressure withxed CO2 ow and extraction temperature at 18 Lh and 35degC respectively (c) eect of CO2 ow and extraction pressure with xedextraction time and extraction temperature at 120min and 35degC respectively (d) eect of extraction time and extraction temperature withxed CO2 ow and extraction pressure at 18 Lh and 25MPa respectively (e) eect of CO2 ow and extraction time with xed extractiontemperature and extraction pressure at 35degC and 25MPa respectively (f ) eect of extraction temperature and extraction pressure with xedCO2 ow and extraction time at 18 Lh and 120min respectively

Journal of Analytical Methods in Chemistry 7

Table 4 Chemical compositions of essential oils

No ComponentsConcentration of essential oil ()

HD SFE1 α-Pinene 071 0672 β-Pinene 431 6003 D-Limonene 02 3554 β-Ocimene ND 0155 8-Methyl 1-hendecene ND 0186 α-Guaiene 025 0457 β-Caryophyllene 246 018 α-Bergamotene ND ND9 3-Carene 046 ND10 α-Cubebene 094 04611 α-Muurolene 026 0312 c-Muurolene 167 0213 α-Copaene 129 11314 β-Bourbonene 197 ND15 β-Guaiene 014 ND

Hydrocarbons 1466 131916 Hinesol 091 2817 2-Borneol ND 07618 Isopulegol 035 01819 trans-Verbenol ND 03320 cis-Verbenol 046 09521 Nerol 035 01922 Geraniol 939 64323 trans-Farnesol ND 13424 Geraniol 2545 102225 trans-Geranylgeraniol 04 13126 3-Methyl cyclohexanol 071 20127 cis-Geranylgeraniol 035 ND28 Globulol 137 05529 c-Eucalyptol ND 08030 Carotol 037 ND31 α-Cadinol 025 14732 Cubenol 055 341

Alcohols 4091 327533 Citronellal 1277 125734 Lauraldehyde 03 01335 Neral 1115 151136 Geranialdehyde 1512 2002

Aldehydes 3934 478337 Citronellyl acetate ND 02338 Citronellyl isobutyrate 061 12739 Geraniol acetate 224 065

Esters 285 21540 D-Carvone ND 01541 D-Verbenone ND 030

Ketones 0 04542 Hexadecane 019 ND43 Dioctylmethane ND 040

Alkanes 019 04044 Rose oxide ND 01045 Geranic acid ND 01446 Eugenol 017 03347 2-Epoxy-trans-p-menthane ND 03948 Caryophyllene oxide 157 04149 3-Decyne 019 ND

Others 174 137Total identified 9969 9814ND not detected

8 Journal of Analytical Methods in Chemistry

assessed using a serial twofold dilution assay and paper discdiffusion assay according to Hu et al [23 24 26] Table 6shows the variation in the antimicrobial properties of theessential oil extracted from the C citronella leaves Amongbacterial strains the E coli has the strongest inhibitory effectby the essential oil Meanwhile the essential oil shows theantifungal or anticandidal activity as well On the otherhand more precise data concerning the antimicrobialproperties of the extracts were obtained by paper disc dif-fusion assay [26] Table 6 indicates the maximal inhibitoryzones for each of the microorganisms that were sensitive tothe extracts which were in the range of 15ndash35mmereinto the greater inhibition was observed in the case ofthe SFE extracts than the others Hence the SFE extracts wassignificant antimicrobial or antifungal activities against all ofthe microorganisms tested except A niger

In summary the SFE extracts have significant antimi-crobial activity against E coli and A niger respectivelyAntimicrobial activity in essential oil depended on mostlyaldehydes and acid esters [22 27] Recently some literaturereported there was the highest level of activity against E coliwith tea oil tannic acid and saponins [6 20 23] Ac-cordingly these observations suggested that the antimi-crobial activity of essential oil may be due to the presence ofester bond and ether bond [28] Other phenolic acid-likephenols were also thought to contribute to plant defensesagainst pests and pathogens [11]

4 Conclusions

e essential oil was attained from C citronella a commonherbaceous plant by supercritical fluid extraction resultingin 440 of essential oil extracted under mild conditionAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE Compared with HDessential oils the SFE essential oils contain fewer impuritiesand had better antioxidant and antimicrobial activitiesSupercritical fluid extraction has presented an outstandingfeature in efficient extraction of active components of the

plant which can be a desirable candidate for the currentextraction processing

Data Availability

e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was funded by the Project of Key Technologies ofHigh-Yield and Carbon Dioxide Emissions in the Full Uti-lization Process of Industrial Oil Plants (2017WK2021)National Sci-Tech Support Plan (2015BAD15B02) and Hu-nan Key Science and Technology Program (2016NK1001)

References

[1] R Pavela ldquoEssential oils for the development of eco-friendlymosquito larvicides a reviewrdquo Industrial Crops and Productsvol 76 no 4 pp 174ndash187 2015

[2] S R Sargenti and F M Lanccedilas ldquoSupercritical fluid extractionof Cymbopogon citratus (DC) Stapfrdquo Chromatographiavol 46 no 5-6 pp 285ndash290 1997

[3] V Sriramavaratharajan J Stephan V Sudha andR Murugan ldquoLeaf essential oil of Cinnamomum agasthya-malayanum from the Western Ghats India-A new source ofcamphorrdquo Industrial Crops and Products vol 86 pp 259ndash2612016

[4] R Pavela E Stepanycheva A Shchenikova T Chermenskayaand M Petrova ldquoEssential oils as prospective fumigants againstTetranychus urticae Kochrdquo Industrial Crops and Productsvol 94 pp 755ndash761 2016

[5] J R Calo P G Crandall C A OrsquoBryan and S C RickeldquoEssential oils as antimicrobials in food systems-a reviewrdquoFood Control vol 54 pp 111ndash119 2015

Table 5 Half-inhibition (IC50) values of antioxidant activities measured using DPPH radical scavenging and 123-phentriol self-oxidation

SamplesIC50 (mgg)

123-Phentriol self-oxidation DPPHSDE 274 plusmn 2 10 plusmn 1SFE 244 plusmn 3 9 plusmn 2AAlowast 5137 plusmn 4 2213 plusmn 4BHTlowast 8029 plusmn 1 895 plusmn 3lowastControl

Table 6 Minimal inhibitory concentration (MIC) of the essential oils with various extraction processes

Immature stagesInhibition zones (mm) MIC (mgmL)

S aureus E coli A niger A fumigatus S aureus E coli A niger A fumigatusSFE 178 plusmn 12 252 plusmn 09 141 plusmn 10 331 plusmn 13 56 plusmn 02 14 plusmn 01 28 plusmn 02 56 plusmn 0SDE 142 plusmn 11 196 plusmn 12 231 plusmn 11 243 plusmn 13 56 plusmn 01 28 plusmn 02 14 plusmn 01 28 plusmn 02Citrallowast 222 plusmn 06 187 plusmn 10 195 plusmn 34 146 plusmn 23 112 plusmn 05 112 plusmn 03 56 plusmn 01 112 plusmn 01lowastControl

Journal of Analytical Methods in Chemistry 9

[6] S Patel and P Gogna ldquoTapping botanicals for essential oilsprogress and hurdles in cancer mitigationrdquo Industrial Cropsand Products vol 76 pp 1148ndash1163 2015

[7] H G Huang Y E Xiao L Q Tian et al ldquoComparative studyon supercritical fluid extraction and steam distillation inextracting chemical constituents and relative contents ofvolatile oil from compatibility of Ramulus cinnamomi andRhizoma zingiberisrdquo Journal of Experimental TraditionalMedical Formulae (Chinese) vol 17 pp 85ndash92 2011

[8] R H Olmedo C M Asensio and N R Grosso ldquoermalstability and antioxidant activity of essential oils from aro-matic plants farmed in Argentinardquo Industrial Crops andProducts vol 69 no 6 pp 21ndash28 2015

[9] E Arranz L Jaime M C Lopez de las Hazas G Reglero andS Santoyo ldquoSupercritical fluid extraction as an alternativeprocess to obtain essential oils with anti-inflammatoryproperties from marjoram and sweet basilrdquo IndustrialCrops and Products vol 67 pp 121ndash129 2015

[10] A Berna A Tarrega M Blasco and S Subirats ldquoSupercriticalCO2 extraction of essential oil from orange peel effect of theheight of the bedrdquo Journal of Supercritical Fluids vol 18 no 3pp 227ndash237 2000

[11] M T Baratta H J D Dorman S G Deans A C FigueiredoJ G Barroso and G Ruberto ldquoAntimicrobial and antioxidantproperties of some commercial essential oilsrdquo Flavour andFragrance Journal vol 13 no 4 pp 235ndash244 2015

[12] H J D Dorman A C Figueiredo J G Barroso andS G Deans ldquoIn vitro evaluation of antioxidant activity ofessential oils and their componentsrdquo Flavour and FragranceJournal vol 15 no 1 pp 12ndash16 2015

[13] C Y Niu F Q Zhang D M Diao and F U Yan ldquoExtractionconditions optimization of essential oil from steamed ginsengwater by response surface methodology and GC-MS analysisrdquoScience and Technology of Food Industry (Chinese) vol 35no 18 pp 310ndash309 2014

[14] M L Harkat B Asma K Madani et al ldquoChemical com-position antibacterial and antioxidant activities of essentialoil of Eucalyptus globulus from Algeriardquo Industrial Crops andProducts vol 78 pp 148ndash153 2015

[15] H Y Kil E S Seong B K Ghimire et al ldquoAntioxidant andantimicrobial activities of crude sorghum extractrdquo FoodChemistry vol 115 no 4 pp 1234ndash1239 2009

[16] J Rakmai B Cheirsilp A Torrado-Agrasar J Simal-Gandaraand J C Mejuto ldquoEncapsulation of yarrow essential oil inhydroxypropyl-beta-cyclodextrin physiochemical character-ization and evaluation of bio-efficaciesrdquo CyTA-Journal ofFood vol 15 no 3 pp 409ndash417 2017

[17] J Rakmai B Cheirsilp J C Mejuto J Simal-Gandara andA Torrado-Agrasar ldquoAntioxidant and antimicrobial prop-erties of encapsulated guava leaf oil in hydroxypropyl-beta-cyclodextrinrdquo Industrial Crops and Products vol 111pp 219ndash225 2018

[18] J Rakmai B Cheirsilp J C Mejuto A Torrado-Agrasar andJ Simal-Gandara ldquoPhysico-chemical characterization andevaluation of bio-efficacies of black pepper essential oil en-capsulated in hydroxypropyl-beta-cyclodextrinrdquo Food Hy-drocolloids vol 65 pp 157ndash164 2016

[19] L H C Carlson R A F Machado C B SpricigoL K Pereira and A Bolzan ldquoExtraction of lemongrass es-sential oil with dense carbon dioxiderdquo Journal of SupercriticalFluids vol 21 no 1 pp 33ndash39 2001

[20] Q Qiu J LIing Y Ding H Chang J Wang and T LiuldquoComparison of supercritical fluid extraction and steamdistillation methods for the extraction of essential oils from

Schizonepeta tenuifolia briqrdquo Chromatography vol 23 no 6pp 646ndash650 2005

[21] G Sodeifian S A Sajadian and N Saadati Ardestani ldquoEx-perimental optimization and mathematical modeling of thesupercritical fluid extraction of essential oil from Eryngiumbillardieri application of simulated annealing (SA) algo-rithmrdquo Journal of Supercritical Fluids vol 127 pp 146ndash1572017

[22] A Gasparetto A Bella Cruz T M Wagner T J BonominiR Correa and A Malheiros ldquoSeasonal variation in thechemical composition antimicrobial and mutagenic potentialof essential oils from Piper cernuumrdquo Industrial Crops andProducts vol 95 pp 256ndash263 2017

[23] E Konoz N Hajikhani and A Abbasi ldquoComparison of twomethods for extraction of dill essential oil by gaschromatography-mass spectrometry coupled with chemo-metric resolution techniquesrdquo International Journal of FoodProperties vol 20 no 1 pp S1002ndashS1015 2017

[24] H J Zhang Y B Cao W B Xue H Ding G F Liu andJ Q Wang ldquoOptimization of extraction process of citronellaessential oil and its gas phase antibacterial propertiesrdquo ChinaCondiment vol 42 pp 15ndash20 2017

[25] M D Guillen N Cabo and J Burillo ldquoCharacterisation ofthe essential oils of some cultivated aromatic plants of in-dustrial interestrdquo Journal of the Science of Food and Agri-culture vol 70 no 3 pp 359ndash363 1996

[26] J Hu S Nie D Huang C Li and M Xie ldquoExtraction ofsaponin from camellia oleifera cake and evaluation of itsantioxidant activityrdquo International Journal of Food Scienceand Technology vol 47 no 8 pp 1676ndash1687 2012

[27] J Singh and N N Tripathi ldquoInhibition of storage fungi ofblackgram (Vigna mungo L) by some essential oilsrdquo Flavourand Fragrance Journal vol 14 no 1 pp 1ndash4 2015

[28] P Matusinsky M Zouhar R Pavela and P Novy ldquoAnti-fungal effect of five essential oils against important pathogenicfungi of cerealsrdquo Industrial Crops and Products vol 67pp 208ndash215 2015

10 Journal of Analytical Methods in Chemistry

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

International Journal ofInternational Journal ofPhotoenergy

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Biochemistry Research International

Hindawiwwwhindawicom Volume 2018

Enzyme Research

Hindawiwwwhindawicom Volume 2018

Journal of

SpectroscopyAnalytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

MaterialsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

BioMed Research International Electrochemistry

International Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

Table 4 Chemical compositions of essential oils

No ComponentsConcentration of essential oil ()

HD SFE1 α-Pinene 071 0672 β-Pinene 431 6003 D-Limonene 02 3554 β-Ocimene ND 0155 8-Methyl 1-hendecene ND 0186 α-Guaiene 025 0457 β-Caryophyllene 246 018 α-Bergamotene ND ND9 3-Carene 046 ND10 α-Cubebene 094 04611 α-Muurolene 026 0312 c-Muurolene 167 0213 α-Copaene 129 11314 β-Bourbonene 197 ND15 β-Guaiene 014 ND

Hydrocarbons 1466 131916 Hinesol 091 2817 2-Borneol ND 07618 Isopulegol 035 01819 trans-Verbenol ND 03320 cis-Verbenol 046 09521 Nerol 035 01922 Geraniol 939 64323 trans-Farnesol ND 13424 Geraniol 2545 102225 trans-Geranylgeraniol 04 13126 3-Methyl cyclohexanol 071 20127 cis-Geranylgeraniol 035 ND28 Globulol 137 05529 c-Eucalyptol ND 08030 Carotol 037 ND31 α-Cadinol 025 14732 Cubenol 055 341

Alcohols 4091 327533 Citronellal 1277 125734 Lauraldehyde 03 01335 Neral 1115 151136 Geranialdehyde 1512 2002

Aldehydes 3934 478337 Citronellyl acetate ND 02338 Citronellyl isobutyrate 061 12739 Geraniol acetate 224 065

Esters 285 21540 D-Carvone ND 01541 D-Verbenone ND 030

Ketones 0 04542 Hexadecane 019 ND43 Dioctylmethane ND 040

Alkanes 019 04044 Rose oxide ND 01045 Geranic acid ND 01446 Eugenol 017 03347 2-Epoxy-trans-p-menthane ND 03948 Caryophyllene oxide 157 04149 3-Decyne 019 ND

Others 174 137Total identified 9969 9814ND not detected

8 Journal of Analytical Methods in Chemistry

assessed using a serial twofold dilution assay and paper discdiffusion assay according to Hu et al [23 24 26] Table 6shows the variation in the antimicrobial properties of theessential oil extracted from the C citronella leaves Amongbacterial strains the E coli has the strongest inhibitory effectby the essential oil Meanwhile the essential oil shows theantifungal or anticandidal activity as well On the otherhand more precise data concerning the antimicrobialproperties of the extracts were obtained by paper disc dif-fusion assay [26] Table 6 indicates the maximal inhibitoryzones for each of the microorganisms that were sensitive tothe extracts which were in the range of 15ndash35mmereinto the greater inhibition was observed in the case ofthe SFE extracts than the others Hence the SFE extracts wassignificant antimicrobial or antifungal activities against all ofthe microorganisms tested except A niger

In summary the SFE extracts have significant antimi-crobial activity against E coli and A niger respectivelyAntimicrobial activity in essential oil depended on mostlyaldehydes and acid esters [22 27] Recently some literaturereported there was the highest level of activity against E coliwith tea oil tannic acid and saponins [6 20 23] Ac-cordingly these observations suggested that the antimi-crobial activity of essential oil may be due to the presence ofester bond and ether bond [28] Other phenolic acid-likephenols were also thought to contribute to plant defensesagainst pests and pathogens [11]

4 Conclusions

e essential oil was attained from C citronella a commonherbaceous plant by supercritical fluid extraction resultingin 440 of essential oil extracted under mild conditionAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE Compared with HDessential oils the SFE essential oils contain fewer impuritiesand had better antioxidant and antimicrobial activitiesSupercritical fluid extraction has presented an outstandingfeature in efficient extraction of active components of the

plant which can be a desirable candidate for the currentextraction processing

Data Availability

e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was funded by the Project of Key Technologies ofHigh-Yield and Carbon Dioxide Emissions in the Full Uti-lization Process of Industrial Oil Plants (2017WK2021)National Sci-Tech Support Plan (2015BAD15B02) and Hu-nan Key Science and Technology Program (2016NK1001)

References

[1] R Pavela ldquoEssential oils for the development of eco-friendlymosquito larvicides a reviewrdquo Industrial Crops and Productsvol 76 no 4 pp 174ndash187 2015

[2] S R Sargenti and F M Lanccedilas ldquoSupercritical fluid extractionof Cymbopogon citratus (DC) Stapfrdquo Chromatographiavol 46 no 5-6 pp 285ndash290 1997

[3] V Sriramavaratharajan J Stephan V Sudha andR Murugan ldquoLeaf essential oil of Cinnamomum agasthya-malayanum from the Western Ghats India-A new source ofcamphorrdquo Industrial Crops and Products vol 86 pp 259ndash2612016

[4] R Pavela E Stepanycheva A Shchenikova T Chermenskayaand M Petrova ldquoEssential oils as prospective fumigants againstTetranychus urticae Kochrdquo Industrial Crops and Productsvol 94 pp 755ndash761 2016

[5] J R Calo P G Crandall C A OrsquoBryan and S C RickeldquoEssential oils as antimicrobials in food systems-a reviewrdquoFood Control vol 54 pp 111ndash119 2015

Table 5 Half-inhibition (IC50) values of antioxidant activities measured using DPPH radical scavenging and 123-phentriol self-oxidation

SamplesIC50 (mgg)

123-Phentriol self-oxidation DPPHSDE 274 plusmn 2 10 plusmn 1SFE 244 plusmn 3 9 plusmn 2AAlowast 5137 plusmn 4 2213 plusmn 4BHTlowast 8029 plusmn 1 895 plusmn 3lowastControl

Table 6 Minimal inhibitory concentration (MIC) of the essential oils with various extraction processes

Immature stagesInhibition zones (mm) MIC (mgmL)

S aureus E coli A niger A fumigatus S aureus E coli A niger A fumigatusSFE 178 plusmn 12 252 plusmn 09 141 plusmn 10 331 plusmn 13 56 plusmn 02 14 plusmn 01 28 plusmn 02 56 plusmn 0SDE 142 plusmn 11 196 plusmn 12 231 plusmn 11 243 plusmn 13 56 plusmn 01 28 plusmn 02 14 plusmn 01 28 plusmn 02Citrallowast 222 plusmn 06 187 plusmn 10 195 plusmn 34 146 plusmn 23 112 plusmn 05 112 plusmn 03 56 plusmn 01 112 plusmn 01lowastControl

Journal of Analytical Methods in Chemistry 9

[6] S Patel and P Gogna ldquoTapping botanicals for essential oilsprogress and hurdles in cancer mitigationrdquo Industrial Cropsand Products vol 76 pp 1148ndash1163 2015

[7] H G Huang Y E Xiao L Q Tian et al ldquoComparative studyon supercritical fluid extraction and steam distillation inextracting chemical constituents and relative contents ofvolatile oil from compatibility of Ramulus cinnamomi andRhizoma zingiberisrdquo Journal of Experimental TraditionalMedical Formulae (Chinese) vol 17 pp 85ndash92 2011

[8] R H Olmedo C M Asensio and N R Grosso ldquoermalstability and antioxidant activity of essential oils from aro-matic plants farmed in Argentinardquo Industrial Crops andProducts vol 69 no 6 pp 21ndash28 2015

[9] E Arranz L Jaime M C Lopez de las Hazas G Reglero andS Santoyo ldquoSupercritical fluid extraction as an alternativeprocess to obtain essential oils with anti-inflammatoryproperties from marjoram and sweet basilrdquo IndustrialCrops and Products vol 67 pp 121ndash129 2015

[10] A Berna A Tarrega M Blasco and S Subirats ldquoSupercriticalCO2 extraction of essential oil from orange peel effect of theheight of the bedrdquo Journal of Supercritical Fluids vol 18 no 3pp 227ndash237 2000

[11] M T Baratta H J D Dorman S G Deans A C FigueiredoJ G Barroso and G Ruberto ldquoAntimicrobial and antioxidantproperties of some commercial essential oilsrdquo Flavour andFragrance Journal vol 13 no 4 pp 235ndash244 2015

[12] H J D Dorman A C Figueiredo J G Barroso andS G Deans ldquoIn vitro evaluation of antioxidant activity ofessential oils and their componentsrdquo Flavour and FragranceJournal vol 15 no 1 pp 12ndash16 2015

[13] C Y Niu F Q Zhang D M Diao and F U Yan ldquoExtractionconditions optimization of essential oil from steamed ginsengwater by response surface methodology and GC-MS analysisrdquoScience and Technology of Food Industry (Chinese) vol 35no 18 pp 310ndash309 2014

[14] M L Harkat B Asma K Madani et al ldquoChemical com-position antibacterial and antioxidant activities of essentialoil of Eucalyptus globulus from Algeriardquo Industrial Crops andProducts vol 78 pp 148ndash153 2015

[15] H Y Kil E S Seong B K Ghimire et al ldquoAntioxidant andantimicrobial activities of crude sorghum extractrdquo FoodChemistry vol 115 no 4 pp 1234ndash1239 2009

[16] J Rakmai B Cheirsilp A Torrado-Agrasar J Simal-Gandaraand J C Mejuto ldquoEncapsulation of yarrow essential oil inhydroxypropyl-beta-cyclodextrin physiochemical character-ization and evaluation of bio-efficaciesrdquo CyTA-Journal ofFood vol 15 no 3 pp 409ndash417 2017

[17] J Rakmai B Cheirsilp J C Mejuto J Simal-Gandara andA Torrado-Agrasar ldquoAntioxidant and antimicrobial prop-erties of encapsulated guava leaf oil in hydroxypropyl-beta-cyclodextrinrdquo Industrial Crops and Products vol 111pp 219ndash225 2018

[18] J Rakmai B Cheirsilp J C Mejuto A Torrado-Agrasar andJ Simal-Gandara ldquoPhysico-chemical characterization andevaluation of bio-efficacies of black pepper essential oil en-capsulated in hydroxypropyl-beta-cyclodextrinrdquo Food Hy-drocolloids vol 65 pp 157ndash164 2016

[19] L H C Carlson R A F Machado C B SpricigoL K Pereira and A Bolzan ldquoExtraction of lemongrass es-sential oil with dense carbon dioxiderdquo Journal of SupercriticalFluids vol 21 no 1 pp 33ndash39 2001

[20] Q Qiu J LIing Y Ding H Chang J Wang and T LiuldquoComparison of supercritical fluid extraction and steamdistillation methods for the extraction of essential oils from

Schizonepeta tenuifolia briqrdquo Chromatography vol 23 no 6pp 646ndash650 2005

[21] G Sodeifian S A Sajadian and N Saadati Ardestani ldquoEx-perimental optimization and mathematical modeling of thesupercritical fluid extraction of essential oil from Eryngiumbillardieri application of simulated annealing (SA) algo-rithmrdquo Journal of Supercritical Fluids vol 127 pp 146ndash1572017

[22] A Gasparetto A Bella Cruz T M Wagner T J BonominiR Correa and A Malheiros ldquoSeasonal variation in thechemical composition antimicrobial and mutagenic potentialof essential oils from Piper cernuumrdquo Industrial Crops andProducts vol 95 pp 256ndash263 2017

[23] E Konoz N Hajikhani and A Abbasi ldquoComparison of twomethods for extraction of dill essential oil by gaschromatography-mass spectrometry coupled with chemo-metric resolution techniquesrdquo International Journal of FoodProperties vol 20 no 1 pp S1002ndashS1015 2017

[24] H J Zhang Y B Cao W B Xue H Ding G F Liu andJ Q Wang ldquoOptimization of extraction process of citronellaessential oil and its gas phase antibacterial propertiesrdquo ChinaCondiment vol 42 pp 15ndash20 2017

[25] M D Guillen N Cabo and J Burillo ldquoCharacterisation ofthe essential oils of some cultivated aromatic plants of in-dustrial interestrdquo Journal of the Science of Food and Agri-culture vol 70 no 3 pp 359ndash363 1996

[26] J Hu S Nie D Huang C Li and M Xie ldquoExtraction ofsaponin from camellia oleifera cake and evaluation of itsantioxidant activityrdquo International Journal of Food Scienceand Technology vol 47 no 8 pp 1676ndash1687 2012

[27] J Singh and N N Tripathi ldquoInhibition of storage fungi ofblackgram (Vigna mungo L) by some essential oilsrdquo Flavourand Fragrance Journal vol 14 no 1 pp 1ndash4 2015

[28] P Matusinsky M Zouhar R Pavela and P Novy ldquoAnti-fungal effect of five essential oils against important pathogenicfungi of cerealsrdquo Industrial Crops and Products vol 67pp 208ndash215 2015

10 Journal of Analytical Methods in Chemistry

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

International Journal ofInternational Journal ofPhotoenergy

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Biochemistry Research International

Hindawiwwwhindawicom Volume 2018

Enzyme Research

Hindawiwwwhindawicom Volume 2018

Journal of

SpectroscopyAnalytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

MaterialsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

BioMed Research International Electrochemistry

International Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

assessed using a serial twofold dilution assay and paper discdiffusion assay according to Hu et al [23 24 26] Table 6shows the variation in the antimicrobial properties of theessential oil extracted from the C citronella leaves Amongbacterial strains the E coli has the strongest inhibitory effectby the essential oil Meanwhile the essential oil shows theantifungal or anticandidal activity as well On the otherhand more precise data concerning the antimicrobialproperties of the extracts were obtained by paper disc dif-fusion assay [26] Table 6 indicates the maximal inhibitoryzones for each of the microorganisms that were sensitive tothe extracts which were in the range of 15ndash35mmereinto the greater inhibition was observed in the case ofthe SFE extracts than the others Hence the SFE extracts wassignificant antimicrobial or antifungal activities against all ofthe microorganisms tested except A niger

In summary the SFE extracts have significant antimi-crobial activity against E coli and A niger respectivelyAntimicrobial activity in essential oil depended on mostlyaldehydes and acid esters [22 27] Recently some literaturereported there was the highest level of activity against E coliwith tea oil tannic acid and saponins [6 20 23] Ac-cordingly these observations suggested that the antimi-crobial activity of essential oil may be due to the presence ofester bond and ether bond [28] Other phenolic acid-likephenols were also thought to contribute to plant defensesagainst pests and pathogens [11]

4 Conclusions

e essential oil was attained from C citronella a commonherbaceous plant by supercritical fluid extraction resultingin 440 of essential oil extracted under mild conditionAlcohols and aldehydes were the main compositions in theessential oils extracted by HD and SFE Compared with HDessential oils the SFE essential oils contain fewer impuritiesand had better antioxidant and antimicrobial activitiesSupercritical fluid extraction has presented an outstandingfeature in efficient extraction of active components of the

plant which can be a desirable candidate for the currentextraction processing

Data Availability

e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was funded by the Project of Key Technologies ofHigh-Yield and Carbon Dioxide Emissions in the Full Uti-lization Process of Industrial Oil Plants (2017WK2021)National Sci-Tech Support Plan (2015BAD15B02) and Hu-nan Key Science and Technology Program (2016NK1001)

References

[1] R Pavela ldquoEssential oils for the development of eco-friendlymosquito larvicides a reviewrdquo Industrial Crops and Productsvol 76 no 4 pp 174ndash187 2015

[2] S R Sargenti and F M Lanccedilas ldquoSupercritical fluid extractionof Cymbopogon citratus (DC) Stapfrdquo Chromatographiavol 46 no 5-6 pp 285ndash290 1997

[3] V Sriramavaratharajan J Stephan V Sudha andR Murugan ldquoLeaf essential oil of Cinnamomum agasthya-malayanum from the Western Ghats India-A new source ofcamphorrdquo Industrial Crops and Products vol 86 pp 259ndash2612016

[4] R Pavela E Stepanycheva A Shchenikova T Chermenskayaand M Petrova ldquoEssential oils as prospective fumigants againstTetranychus urticae Kochrdquo Industrial Crops and Productsvol 94 pp 755ndash761 2016

[5] J R Calo P G Crandall C A OrsquoBryan and S C RickeldquoEssential oils as antimicrobials in food systems-a reviewrdquoFood Control vol 54 pp 111ndash119 2015

Table 5 Half-inhibition (IC50) values of antioxidant activities measured using DPPH radical scavenging and 123-phentriol self-oxidation

SamplesIC50 (mgg)

123-Phentriol self-oxidation DPPHSDE 274 plusmn 2 10 plusmn 1SFE 244 plusmn 3 9 plusmn 2AAlowast 5137 plusmn 4 2213 plusmn 4BHTlowast 8029 plusmn 1 895 plusmn 3lowastControl

Table 6 Minimal inhibitory concentration (MIC) of the essential oils with various extraction processes

Immature stagesInhibition zones (mm) MIC (mgmL)

S aureus E coli A niger A fumigatus S aureus E coli A niger A fumigatusSFE 178 plusmn 12 252 plusmn 09 141 plusmn 10 331 plusmn 13 56 plusmn 02 14 plusmn 01 28 plusmn 02 56 plusmn 0SDE 142 plusmn 11 196 plusmn 12 231 plusmn 11 243 plusmn 13 56 plusmn 01 28 plusmn 02 14 plusmn 01 28 plusmn 02Citrallowast 222 plusmn 06 187 plusmn 10 195 plusmn 34 146 plusmn 23 112 plusmn 05 112 plusmn 03 56 plusmn 01 112 plusmn 01lowastControl

Journal of Analytical Methods in Chemistry 9

[6] S Patel and P Gogna ldquoTapping botanicals for essential oilsprogress and hurdles in cancer mitigationrdquo Industrial Cropsand Products vol 76 pp 1148ndash1163 2015

[7] H G Huang Y E Xiao L Q Tian et al ldquoComparative studyon supercritical fluid extraction and steam distillation inextracting chemical constituents and relative contents ofvolatile oil from compatibility of Ramulus cinnamomi andRhizoma zingiberisrdquo Journal of Experimental TraditionalMedical Formulae (Chinese) vol 17 pp 85ndash92 2011

[8] R H Olmedo C M Asensio and N R Grosso ldquoermalstability and antioxidant activity of essential oils from aro-matic plants farmed in Argentinardquo Industrial Crops andProducts vol 69 no 6 pp 21ndash28 2015

[9] E Arranz L Jaime M C Lopez de las Hazas G Reglero andS Santoyo ldquoSupercritical fluid extraction as an alternativeprocess to obtain essential oils with anti-inflammatoryproperties from marjoram and sweet basilrdquo IndustrialCrops and Products vol 67 pp 121ndash129 2015

[10] A Berna A Tarrega M Blasco and S Subirats ldquoSupercriticalCO2 extraction of essential oil from orange peel effect of theheight of the bedrdquo Journal of Supercritical Fluids vol 18 no 3pp 227ndash237 2000

[11] M T Baratta H J D Dorman S G Deans A C FigueiredoJ G Barroso and G Ruberto ldquoAntimicrobial and antioxidantproperties of some commercial essential oilsrdquo Flavour andFragrance Journal vol 13 no 4 pp 235ndash244 2015

[12] H J D Dorman A C Figueiredo J G Barroso andS G Deans ldquoIn vitro evaluation of antioxidant activity ofessential oils and their componentsrdquo Flavour and FragranceJournal vol 15 no 1 pp 12ndash16 2015

[13] C Y Niu F Q Zhang D M Diao and F U Yan ldquoExtractionconditions optimization of essential oil from steamed ginsengwater by response surface methodology and GC-MS analysisrdquoScience and Technology of Food Industry (Chinese) vol 35no 18 pp 310ndash309 2014

[14] M L Harkat B Asma K Madani et al ldquoChemical com-position antibacterial and antioxidant activities of essentialoil of Eucalyptus globulus from Algeriardquo Industrial Crops andProducts vol 78 pp 148ndash153 2015

[15] H Y Kil E S Seong B K Ghimire et al ldquoAntioxidant andantimicrobial activities of crude sorghum extractrdquo FoodChemistry vol 115 no 4 pp 1234ndash1239 2009

[16] J Rakmai B Cheirsilp A Torrado-Agrasar J Simal-Gandaraand J C Mejuto ldquoEncapsulation of yarrow essential oil inhydroxypropyl-beta-cyclodextrin physiochemical character-ization and evaluation of bio-efficaciesrdquo CyTA-Journal ofFood vol 15 no 3 pp 409ndash417 2017

[17] J Rakmai B Cheirsilp J C Mejuto J Simal-Gandara andA Torrado-Agrasar ldquoAntioxidant and antimicrobial prop-erties of encapsulated guava leaf oil in hydroxypropyl-beta-cyclodextrinrdquo Industrial Crops and Products vol 111pp 219ndash225 2018

[18] J Rakmai B Cheirsilp J C Mejuto A Torrado-Agrasar andJ Simal-Gandara ldquoPhysico-chemical characterization andevaluation of bio-efficacies of black pepper essential oil en-capsulated in hydroxypropyl-beta-cyclodextrinrdquo Food Hy-drocolloids vol 65 pp 157ndash164 2016

[19] L H C Carlson R A F Machado C B SpricigoL K Pereira and A Bolzan ldquoExtraction of lemongrass es-sential oil with dense carbon dioxiderdquo Journal of SupercriticalFluids vol 21 no 1 pp 33ndash39 2001

[20] Q Qiu J LIing Y Ding H Chang J Wang and T LiuldquoComparison of supercritical fluid extraction and steamdistillation methods for the extraction of essential oils from

Schizonepeta tenuifolia briqrdquo Chromatography vol 23 no 6pp 646ndash650 2005

[21] G Sodeifian S A Sajadian and N Saadati Ardestani ldquoEx-perimental optimization and mathematical modeling of thesupercritical fluid extraction of essential oil from Eryngiumbillardieri application of simulated annealing (SA) algo-rithmrdquo Journal of Supercritical Fluids vol 127 pp 146ndash1572017

[22] A Gasparetto A Bella Cruz T M Wagner T J BonominiR Correa and A Malheiros ldquoSeasonal variation in thechemical composition antimicrobial and mutagenic potentialof essential oils from Piper cernuumrdquo Industrial Crops andProducts vol 95 pp 256ndash263 2017

[23] E Konoz N Hajikhani and A Abbasi ldquoComparison of twomethods for extraction of dill essential oil by gaschromatography-mass spectrometry coupled with chemo-metric resolution techniquesrdquo International Journal of FoodProperties vol 20 no 1 pp S1002ndashS1015 2017

[24] H J Zhang Y B Cao W B Xue H Ding G F Liu andJ Q Wang ldquoOptimization of extraction process of citronellaessential oil and its gas phase antibacterial propertiesrdquo ChinaCondiment vol 42 pp 15ndash20 2017

[25] M D Guillen N Cabo and J Burillo ldquoCharacterisation ofthe essential oils of some cultivated aromatic plants of in-dustrial interestrdquo Journal of the Science of Food and Agri-culture vol 70 no 3 pp 359ndash363 1996

[26] J Hu S Nie D Huang C Li and M Xie ldquoExtraction ofsaponin from camellia oleifera cake and evaluation of itsantioxidant activityrdquo International Journal of Food Scienceand Technology vol 47 no 8 pp 1676ndash1687 2012

[27] J Singh and N N Tripathi ldquoInhibition of storage fungi ofblackgram (Vigna mungo L) by some essential oilsrdquo Flavourand Fragrance Journal vol 14 no 1 pp 1ndash4 2015

[28] P Matusinsky M Zouhar R Pavela and P Novy ldquoAnti-fungal effect of five essential oils against important pathogenicfungi of cerealsrdquo Industrial Crops and Products vol 67pp 208ndash215 2015

10 Journal of Analytical Methods in Chemistry

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

International Journal ofInternational Journal ofPhotoenergy

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Biochemistry Research International

Hindawiwwwhindawicom Volume 2018

Enzyme Research

Hindawiwwwhindawicom Volume 2018

Journal of

SpectroscopyAnalytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

MaterialsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

BioMed Research International Electrochemistry

International Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

[6] S Patel and P Gogna ldquoTapping botanicals for essential oilsprogress and hurdles in cancer mitigationrdquo Industrial Cropsand Products vol 76 pp 1148ndash1163 2015

[7] H G Huang Y E Xiao L Q Tian et al ldquoComparative studyon supercritical fluid extraction and steam distillation inextracting chemical constituents and relative contents ofvolatile oil from compatibility of Ramulus cinnamomi andRhizoma zingiberisrdquo Journal of Experimental TraditionalMedical Formulae (Chinese) vol 17 pp 85ndash92 2011

[8] R H Olmedo C M Asensio and N R Grosso ldquoermalstability and antioxidant activity of essential oils from aro-matic plants farmed in Argentinardquo Industrial Crops andProducts vol 69 no 6 pp 21ndash28 2015

[9] E Arranz L Jaime M C Lopez de las Hazas G Reglero andS Santoyo ldquoSupercritical fluid extraction as an alternativeprocess to obtain essential oils with anti-inflammatoryproperties from marjoram and sweet basilrdquo IndustrialCrops and Products vol 67 pp 121ndash129 2015

[10] A Berna A Tarrega M Blasco and S Subirats ldquoSupercriticalCO2 extraction of essential oil from orange peel effect of theheight of the bedrdquo Journal of Supercritical Fluids vol 18 no 3pp 227ndash237 2000

[11] M T Baratta H J D Dorman S G Deans A C FigueiredoJ G Barroso and G Ruberto ldquoAntimicrobial and antioxidantproperties of some commercial essential oilsrdquo Flavour andFragrance Journal vol 13 no 4 pp 235ndash244 2015

[12] H J D Dorman A C Figueiredo J G Barroso andS G Deans ldquoIn vitro evaluation of antioxidant activity ofessential oils and their componentsrdquo Flavour and FragranceJournal vol 15 no 1 pp 12ndash16 2015

[13] C Y Niu F Q Zhang D M Diao and F U Yan ldquoExtractionconditions optimization of essential oil from steamed ginsengwater by response surface methodology and GC-MS analysisrdquoScience and Technology of Food Industry (Chinese) vol 35no 18 pp 310ndash309 2014

[14] M L Harkat B Asma K Madani et al ldquoChemical com-position antibacterial and antioxidant activities of essentialoil of Eucalyptus globulus from Algeriardquo Industrial Crops andProducts vol 78 pp 148ndash153 2015

[15] H Y Kil E S Seong B K Ghimire et al ldquoAntioxidant andantimicrobial activities of crude sorghum extractrdquo FoodChemistry vol 115 no 4 pp 1234ndash1239 2009

[16] J Rakmai B Cheirsilp A Torrado-Agrasar J Simal-Gandaraand J C Mejuto ldquoEncapsulation of yarrow essential oil inhydroxypropyl-beta-cyclodextrin physiochemical character-ization and evaluation of bio-efficaciesrdquo CyTA-Journal ofFood vol 15 no 3 pp 409ndash417 2017

[17] J Rakmai B Cheirsilp J C Mejuto J Simal-Gandara andA Torrado-Agrasar ldquoAntioxidant and antimicrobial prop-erties of encapsulated guava leaf oil in hydroxypropyl-beta-cyclodextrinrdquo Industrial Crops and Products vol 111pp 219ndash225 2018

[18] J Rakmai B Cheirsilp J C Mejuto A Torrado-Agrasar andJ Simal-Gandara ldquoPhysico-chemical characterization andevaluation of bio-efficacies of black pepper essential oil en-capsulated in hydroxypropyl-beta-cyclodextrinrdquo Food Hy-drocolloids vol 65 pp 157ndash164 2016

[19] L H C Carlson R A F Machado C B SpricigoL K Pereira and A Bolzan ldquoExtraction of lemongrass es-sential oil with dense carbon dioxiderdquo Journal of SupercriticalFluids vol 21 no 1 pp 33ndash39 2001

[20] Q Qiu J LIing Y Ding H Chang J Wang and T LiuldquoComparison of supercritical fluid extraction and steamdistillation methods for the extraction of essential oils from

Schizonepeta tenuifolia briqrdquo Chromatography vol 23 no 6pp 646ndash650 2005

[21] G Sodeifian S A Sajadian and N Saadati Ardestani ldquoEx-perimental optimization and mathematical modeling of thesupercritical fluid extraction of essential oil from Eryngiumbillardieri application of simulated annealing (SA) algo-rithmrdquo Journal of Supercritical Fluids vol 127 pp 146ndash1572017

[22] A Gasparetto A Bella Cruz T M Wagner T J BonominiR Correa and A Malheiros ldquoSeasonal variation in thechemical composition antimicrobial and mutagenic potentialof essential oils from Piper cernuumrdquo Industrial Crops andProducts vol 95 pp 256ndash263 2017

[23] E Konoz N Hajikhani and A Abbasi ldquoComparison of twomethods for extraction of dill essential oil by gaschromatography-mass spectrometry coupled with chemo-metric resolution techniquesrdquo International Journal of FoodProperties vol 20 no 1 pp S1002ndashS1015 2017

[24] H J Zhang Y B Cao W B Xue H Ding G F Liu andJ Q Wang ldquoOptimization of extraction process of citronellaessential oil and its gas phase antibacterial propertiesrdquo ChinaCondiment vol 42 pp 15ndash20 2017

[25] M D Guillen N Cabo and J Burillo ldquoCharacterisation ofthe essential oils of some cultivated aromatic plants of in-dustrial interestrdquo Journal of the Science of Food and Agri-culture vol 70 no 3 pp 359ndash363 1996

[26] J Hu S Nie D Huang C Li and M Xie ldquoExtraction ofsaponin from camellia oleifera cake and evaluation of itsantioxidant activityrdquo International Journal of Food Scienceand Technology vol 47 no 8 pp 1676ndash1687 2012

[27] J Singh and N N Tripathi ldquoInhibition of storage fungi ofblackgram (Vigna mungo L) by some essential oilsrdquo Flavourand Fragrance Journal vol 14 no 1 pp 1ndash4 2015

[28] P Matusinsky M Zouhar R Pavela and P Novy ldquoAnti-fungal effect of five essential oils against important pathogenicfungi of cerealsrdquo Industrial Crops and Products vol 67pp 208ndash215 2015

10 Journal of Analytical Methods in Chemistry

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

International Journal ofInternational Journal ofPhotoenergy

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Biochemistry Research International

Hindawiwwwhindawicom Volume 2018

Enzyme Research

Hindawiwwwhindawicom Volume 2018

Journal of

SpectroscopyAnalytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

MaterialsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

BioMed Research International Electrochemistry

International Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

TribologyAdvances in

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

International Journal ofInternational Journal ofPhotoenergy

Hindawiwwwhindawicom Volume 2018

Journal of

Chemistry

Hindawiwwwhindawicom Volume 2018

Advances inPhysical Chemistry

Hindawiwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Applied ChemistryJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Biochemistry Research International

Hindawiwwwhindawicom Volume 2018

Enzyme Research

Hindawiwwwhindawicom Volume 2018

Journal of

SpectroscopyAnalytical ChemistryInternational Journal of

Hindawiwwwhindawicom Volume 2018

MaterialsJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

BioMed Research International Electrochemistry

International Journal of

Hindawiwwwhindawicom Volume 2018

Na

nom

ate

ria

ls

Hindawiwwwhindawicom Volume 2018

Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom