editorial flavonoids: separation and...

EditorialFlavonoids: Separation and Quantitation

Wanchai De-Eknamkul,1 Kaoru Umehara,2 and Jan Frederik Stevens3

1Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10330, Thailand2School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan3Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331, USA

Correspondence should be addressed to Wanchai De-Eknamkul; [email protected]

Received 13 January 2015; Accepted 13 January 2015

Copyright © 2015 Wanchai De-Eknamkul et al.This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

Flavonoids, products of secondary metabolism, are widelydistributed in the plant kingdom. They belong to the largegroup of plant polyphenols and represent one of the mostabundant classes of phytochemicals that are ubiquitouslypresent in fruits, vegetables, medicinal plants, and theirproducts.Thousands of flavonoids, existing both in free formand as glycosides, have been characterized and reported inthe literature. Many of them are known to play ecologicalroles in the interactions of plants with their environment.Some flavonoids are known to act as signaling molecules andothers as defense agents to fend off herbivores.

In addition, flavonoids are renowned for their numeroushealth benefits. Scientific evidence supports epidemiologicalobservations that regular intake of dietary flavonoids reducesthe risk of oxidative-stress mediated pathogenesis of humandiseases as well as of age-related ailments. In many cases,however, it is necessary to release the flavonoids from plantmaterials by extraction before they can be evaluated forbiological and pharmacological activity. For further develop-ment of health products or herbal drugs, plant extracts areusually characterized by chromatographic means for qualitycontrol purposes or subjected to separation to obtain thebioactive flavonoid constituents.

The increasing interest in bioactive flavonoids from anecological or health perspective has resulted in the isolationand structure elucidation of many novel and minor naturalflavonoids with interesting biological activities. At the sametime, several techniques of chromatography have been fur-ther developed for efficient separation, identification, andquantitation of the flavonoids.

In this special issue, the contributions consist of tenpapers covering several aspects of flavonoids analysis, rang-ing from methods and techniques of extraction, separation,and quantitation to phytochemical profiling and identifica-tion of bioactive flavonoids.

For the optimization of extraction, a chemometricapproach based on response surface methodology was usedin two studies. One is for the optimization of ionic liquid-based simultaneous ultrasonic and microwave-assistedextraction for isolating rutin and quercetin from leaves ofAbutilon theophrasti (C. Zhao et al.) and the other for theoptimization of reflux conditions for total flavonoid andtotal phenolic extraction and enhanced antioxidant capacityin Pandanus amaryllifolius (A. Ghasemzadeh and H. Z. E.Jaafar). A similar microwave-assisted method was used forthe simultaneous extraction of luteolin and apigenin fromPaeonia ostii pods (H. Wang et al.).

For the separation and quantitation of flavonoids, in addi-tion to the generally usedHPLC-UV, the technique of HPLC-MS/MS is exemplified in two papers: “Flavonoids in JuglansregiaL. Leaves andEvaluation of InVitroAntioxidantActivityvia Intracellular and Chemical Methods” (M.-H. Zhao et al.)and “Chemical Characterization of Fruit Wine Made fromOblacinska Sour Cherry” (M. Pantelic et al.). The latter alsoused the powerful UHPLC system for separation of the con-stituents. Furthermore, the technique of HPTLC was shownto obtain good separation of the group flavone C-glycosidesas reported in the paper entitled “Analysis of Flavone C-Glycosides in the Leaves of Clinacanthus nutans (Burm. f.)Lindau byHPTLC andHPLC-UV/DAD” by J. L. Chelyn et al.

Hindawi Publishing Corporatione Scientific World JournalVolume 2015, Article ID 874148, 2 pageshttp://dx.doi.org/10.1155/2015/874148

2 The Scientific World Journal

Interestingly, the paper “Phytochemical Profiles andAntioxidant and Antimicrobial Activities of the Leaves ofZanthoxylum bungeanum” by Y. Zhang et al. showed verynicely the simultaneous separation of 12 flavonoids andrelated compounds in a single HPLC run to obtain phyto-chemical profiles of the plant material. Equally impressive isthe paper “Phenolic Composition and Antioxidant Activityof Malus domestica Leaves” (M. Liaudanskas et al.) whichshowed complete separation of all 13 flavonoids and phenolicpresent in apple leaf extracts. Similarly, nine closely relatedflavones differing from each other by variation in ring substi-tutionwere also successfully separated as demonstrated in thereport “HPLC-Fingerprints and Antioxidant Constituents ofPhyla nodiflora” by F.-J. Lin et al.

Finally, there is one paper reporting on the isolationand structure elucidation of the flavonoids afzelin and iso-quercitrin from Ocotea notata (I. F. B. Costa et al.). Bothflavonoids strongly exhibited antimycobacterial activity andinhibition of nitric oxide production by macrophages.

We hope that all the interesting results published in thisspecial issue will stimulate the continuing efforts to developsuperior methods of flavonoid separation and quantitativeanalysis.

Acknowledgments

We thank the authors of the submitted papers for their contri-bution. The preparation of this special issue would not havebeen possible without the generous support and dedicationof experts who evaluated the submitted papers.

Wanchai De-EknamkulKaoru Umehara

Jan Frederik Stevens

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