Indian Journal of Fibre & Textile Research Vol. 30, December 2005, pp. 43 1 -436

Development of ecofriendly antimicrobial textile finishes using herbs

G Thilagavathi" & K Rajendrakumar Department of Textile Technology, PSG College of Technology, Coimbatore 641 004, India

and R Rajendran

Department of Microbiology, PSG College of Arts & Science, Coimbatore 641 0 1 4, India

Received 14 May 2004; revised received and accepted 29 December 2004

Various herbal species were screened for their antimicrobial activities by employing preliminary (qualitative) antimicrobial tests. Methanolic extraction procedure was followed for extracting the active substances from herbs. Antimicrobial efficacy was assayed by AATCC (agar diffusion and parallel streak) method and Hohenstein modified challenge test. The neem leaves (Azadirachta indica), prickly chaff flower (Achyrallthus aspera), tulsi leaves (Ocimum basilicum) and pomegranate rind (Pullica granatum) were found to exhibit antimicrobial activity against the strains of Staphylococcus aureus and E. coli. Neem ranked first followed by pomegranate and prickly chaff flower. Despite the negative results of tulsi in the qualitative tests, i t showed 73% bacterial reduction in the quantitative challenge test. The treated fabric samples exhibited resistance to degradabi lity as tested by digging soil test.

Keywords: Antimicrobial textiles, Achyranthus aspera, Azadirachta indica, Bacteriostasis, Ocimum basilicum, Punica granatum

IPC Code: Int. CI.7 D06M 1 6/00, D06M23/00

1 Introduction The continuing population explosion and the

worsening environmental pollution make it necessary for researchers to find new ways of enhancing the health and hygiene qualities of consumer products. The problems caused by microbes are numerous and further aggravated in tropical and subtropical regions. Pathogenic micro-organisms of bacteria, mold and fungi cause cross infection, l ung-related diseases, respiratory disorders and fou l odour in addition to staining, discolouring, and degradation of textile substrates l -9.

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Antimicrobial finishes on fabrics can protect human beings against microbes. The application of antimicrobial textile finishes at present is confined to speciality products in the medical, technical, industrial, home furnishing and apparel categories9. Though a number of commercial antimicrobial agents have been introduced in the market, their compliance with the regulation� imposed by International Bodies like EPU is sti l l not proven. Recent developments on chitosan (a naturally occurring biopolymer) have opened up new avenues in this area of research 1 0.

"To whom all the correspondence should be addressed. Phone: 2572 177; Fax: +9 1 - 422 - 2573833; E-mail: g_thilaga@hotmail.com

The present investigation aims at developing an ecofriendly, natural antimicrobial finish from herbs for textile application. A number of Indian herbs do contain antibacterial, antifungal and antiviral properties 1 1 , 1 2 . Studies 1 3. 1 4 reveal that some specific species of herbs having antimicrobial activity are suitable for textile application. I n this context, selective species of herbs were screened for their antimicrobial activities and the extracts were applied to cotton fabrics. An extensive study was conducted to 'assess the anti�icrobial effectiveness of the herbs by employing standard test methods l 5 and the findings are discussed in this paper.

2 Materials and Methods

2.1 Fabric

Cotton fabric with the fol lowing specifications was desized, scoured and b leached prior to the application of antimicrobial finish: 80 ends/inch, 64 picks/inch, 40s count and plain weave.

B leaching includes washing-souring-washing. Two . grams of sodium hypochlorite/litre was used for bleaching the fabric. The fabric was scoured with 1 % HCI, washed twice with hot water fol lowed by cold water and dried.

432 INDIAN 1. FIBRE TEXT. RES., DECEMBER 2005

2.2 Antimicrobial Herbs

Neem (Azadirachta indica), tulsi (Ocimum sanctum), pomegranate rind (Punica granatum ) and prickly chaff flower (Achyranthus aspera) were the plant species chosen based on their effectiveness on preliminary studies. Fresh leaves of neem and tulsi, and prickly chaff flower were shadow dried and made into a fine powder. In the similar way, the fine powder of pomegranate rind was obtained. Methanolic extracts of respective herbal powder were obtained by treating with methanol at room temperature, resulting i n active substances being dissolved in methanol .

2.3 Method of Application

Methanolic extracts of herbs were applied to cotton fabric by dipping in bath at material-to-liquor ratio of 1 : 1 0. The fabric was then dried at 800e for 1 5 min to remove the moisture. Finally, the fabric samples were tested for antimicrobial activity as per the standard AA Tee test methods.

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2.4 Antimicrobial Activity Assessment

Antimicrobial activity was evaluated by both qualitative and quantitative test methods. The following are the descriptions of test methods employed for this study.

2.4.1 Parallel Streak Method

Treated and untreated samples were placed in intimate contact with AA Tee bacteriostasis agar, which has been previously streaked with an innoculam of test organisms. After incubation, a streak of interrupted growth underneath and along the side of the test material indicates antibacterial effectiveness of the fabric. Parallel

streak test was performed using AA Tee test method 1 47- 1 988.

2.4.2 Agar Diffusion Method

Treated and untreated (control) fabric samples were placed in i ntimate contact with AATCC bacteriostasis agar, which has been previously inoculated (Mat culture) with an innoculam of test organisms. After i ncubation, a clear area of uninterrupted growth underneath and along the side of the test material indicates antibacterial effectiveness of the fabric . The area of inhibition zone is a measure of antimicrobial effectiveness.

2.4.3 Hohe1lstei1l Modified Challenge Test

Specimens of the test material were shaken in a known concentration of bacterial suspension and the reduction i n bacterial activity in standard time was measured. The efficiency of the antimicrobial treatment was determined by comparing the reduction in bacterial concentration of the treated sample with that of control sample expressed as a percentage reduction in standard time. 2.4.4 Digging Soil Test

The finished and unfinished fabric samples were buried inside the microbial active soil at 1 -3 cm depth. After two weeks of incubation at room temperature the samples were removed and washed thoroughly off soil particles and examined for any degradation by visual experience and through SEM surface topography. 3 Results and Discussion 3.1 Antimicrobial Activity using Agar Diffusion Test

Fig. l shows the result of agar diffusion test for antimicrobial effectiveness against standard test

Fig. I-Antimicrobial efficiency of neem using agar diffusion test [A -activity against E.coli, and B -activity against S.aureus; I - control, and 2 - antimicrobial finished samplesl

THILAGA V ATHI et af.: DEVELOPMENT OF ANTIMICROBIAL TEXTILE FINISHES 433

cultures, viz. Staphylococcus aureus (gram positive) and E.coli (gram negative) organisms. Specimen 1 i n the figure represents untreated sample and Specimen 2 represents the methanolic neem extract finished sample. The zone of inhibition is visible on the treated fabric for both the test cultures.

Fig. 2 compares the activities of neem and pomegranate treated fabric samples against both the organisms. From the size of inhibition zone, it is clear that the antimicrobial activity of neem treated sample is superior to that of pomegranate treated sample for both the test cul tures. Neem samples exhibit 5 . 8 mm

zone of inhibition for s'aureus and 3.3 mm zone of inhibition for E.coli. Pomegranate finished samples show inhibition zone sizes of 3.6 mm and 2.2 mm for S.aureus and E.coli respectively . It is evident that the antimicrobial activity of both the samples is greater for S.aureus than for E.coli.

3.2 Antimicrobial Activity using Parallel Streak Method

Fig. 3 shows the antimicrobial activity of neem, pomegranate, and prickly chaff tlower as tested by parallel streak method for S.aureus. A complete plate clearance of microbes was observed for neem treated fabric samples.

Fig. 2-Antimicrobial efficiency of neem and pomegranate using agar diffusion test [A - activity against E.coli, and B - activity against S.ut/rells; I - pomegranate treated fabric. and 2 - neem treated fabric]

Fig. 3-Antimicrobial activity against S.aureus using parallel streak method [A and C - neem treated fabric, B - pomegranate treated fabric, and D - prickly chaff flower treated fabric]

434 INDIAN 1. FIB RE TEXT. RES., DECEMBER 2005

The zone of i nhibit ion is 4.4 mm for pomegranate ( 8 ) and 3 .0 mm for prickly chaff flower (D) treated

fabric samples.

The ant imicrobial act i v i ty of neem, pomegranate

and prickly chaff flower as tested by parallel streak

method for E. coli is shown in Fig. 4. A s i mi lar trend as above i s observed, showi ng that the neem treated

fabric samples produce a complete p late c learance of microbes whereas the act i v i ty is moderate for pomegranate (zone of i nh ibi t ion of 2.9 mm) and very mild for prickly chaff tlower.

3.3 Antimicrobial Activity using Hohenstein Modified Test

The ant i m i crobial act i v i ty in terms of quant i tati v e

bacterial reduction i s evaluated b y Hohenste in

modified test method (challen ge test ) . The bacteriostatic and bacteri c idal effects are eval uated by

the fol lowing formulae :

Growth control : F = M" - Ma B acteriostat i c acti v i ty

B acteric idal act i v i ty : L = MlI- Me : S = M" - Me

where M" i s the i ni t ial concentration of cel ls ( both

fi n i shed and u n fi n i shed con trol ) : Mb• the fi nal

Fig. -l--f\ n t i lll icrohial act i v i ty against Eco/i lIs ing p:ml l i e l streak method IA and C - nccill treated fabriL'. B - pOll1eg ranate t reated (a hric . . tIlei D--pric k l y charI' flower treated fahric J

Fig. 5--Anti lllicrobial act i vi'ty using Hoilens'(ei n modified test ITuoe I -uniilOcu laied conf�ol fabric. Tobe 2'- 'Inoculated control fabric. and Tubes 3-9-inoculated finished fabricsJ

. . . . ,

THILAGA V ATHI et af.: DEVELOPMENT OF ANTIMICROBIAL TEXTILE FINISH ES 435

Fig. 6--Antimicrobial activ i ty using digging soil test I A - untreatcd fnbric. B - Ilecm lre:ned f<lbric. C - pomegran<lte treated fabric. and D - prickly ch<lff flower treated f<lbricl

concentration of cel ls in control sample after 1 8 h: and Me, the final concentration of cel l s in test sample after 1 8 h .

Fig. 5 depicts the test against E.coli in AATCC bacteriostasis broth . The uninoculated control, inoculated control and inocu lated finished samples are evaluated for percentage bacterial reduction . It is observed that the neem has 1 00% bacterial reduction fol lowed by pomegranate with 90% reduction and prickly chaff tlower with 82% reduction. Tulsi , which shows no activity in the preliminary tests, exhibits a bacterial reduction of 73% in chal lenge test.

3.4 Antimicrobial Activity using Digging Soil Test

The results of digging in soil test are shown in the Fig. 6. The untreated sample (A) is degraded to a large extent as seen by the patchy appearance. All the finished fabric samples, viz. neem ( 8 ), pomegranate ( C), and pnckly chaff flower (D) treated show resistance to microbial attack.

3.4.1 Surface Tupugraphy frum SEM

The scanning electron micrographs of the untreated and neem treated fabrics after digging soil test are presented in the Fig. 7 . The untreated fabric is degraded to iarge extent, whereas the neem treated fabric shows considerable resistance to degradation.

Fig. 8 shows the damages occurred to the untreated fabric (x 200). The structural damages on yarn and fibre caused by microbes are clearly visible in the

Fig. 7-Scanning electron micrographs of fabric after d igging in soil tests (a) untreated, and (b) neem tre<lted

436 INDIAN J. FIBRE TEXT. RES., DECEMBER 2005

Fig. 8-SEM magnified image (x2oo) of the degraded portion of untreated fabric

filament l ike lines visible at the damaged portions could be due to the growth of microbes.

These SEM photographs are used only to show the relative difference in microbial degradation between finished and untreated samples. It may be true that a bacterium always does not attack fibres along nanometer bandwidths.

3.4.2 Durability of Finished Fabric

Though the extensive study was not conducted to estimate the durabil ity of antimicrobial finish, l imited trials were conducted to measure the effectiveness of protection after few numbers of washing cycles. I t was observed that the effecti veness reduces by 1 0 -15% after 4 washes. 4 Conclusions

4.1 Neem leaves, pomegranate fruit rind, tulsi leaves, and prickly chaff flower exhibit their potential for antimicrobial activity in clearly measurable terms.

4.2 Neem exhibits maximum antimicrobial activity in all the tests conducted and it also accounted for 1 00% protection against both S.aureus and E.coli in the quantitative test.

4.3 Pomegranate and prickly chaff flower are found to have antimicrobial properties. Though their level of

activity i s lower than that of neem, there is scope to improve their antimicrobial activity by increasing the concentration of extract and also by attempting process optimization.

4.4 Tulsi shows trace antimicrobial activity in the preliminary tests but exhibits 73% bacterial reduction in the challenge test.

4.5 Compared to untreated samples, all herbal finished fabrics show h igher resistance to degradation as measured through the digging soil test. Further evidence of higher damage in untreated samples is observed in the SEM pictures of treated and untreated fabrics dug out from the soil .

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