Validated thin-layer chromatography-densitometric method for simultaneous determination of piperine and plumbagin in “Benjakul”thai polyherbal formulation and its antioxidant activities

Abstract

© 2018, Faculty of Pharmaceutical Sciences, Chulalongkorn University. All rights reserved. Objective: The purpose of this study was to evaluate antioxidant activity and quantitative analysis of the piperine and plumbagin content in “Benjakul (BEN),” a Thai polyherbal formulation using the thin-layer chromatography (TLC)-densitometric method. BEN has been recognized in the national list of herbal medicinal products of Thailand as a carminative and adaptogenic drug. The formula consists, in equal proportions, of the following ingredients: Root of Plumbago indica Linn., root of Piper sarmentosum Roxb., stem of Piper interruptum Opiz., fruit of Piper longum Linn., and rhizome of Zingiber officinale Roscoe. Materials and Methods: The TLC densitometric method was validated and developed for the simultaneous determination of piperine and plumbagin in the BEN product. Results: The proposed TLC-densitometric method showed acceptable validation parameters. The content of piperine and plumbagin in the in-house preparation and four commercial BEN products was found in the ranges of 0.98 ± 0.0007–1.71 ± 0.0011% w/w and not detected - 0.61 ± 0.0009% w/w, respectively. The total phenolic contents were in the range of 5.8 ± 0.4–45.4 ± 1.3 g gallic acid equivalent/100 g extract. For the 2,2-diphenyl,1-picrylhydrazine (DPPH) scavenging activity, the effective concentration50 values were in the range of 59.1 ± 8.5–478.0 ± 13.7 µg/ml, while the 2,2’-Azino-bis(3-ethyl benzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging activities yielded results in the range of 22.0 ± 1.2–90.3 ± 3.8 mg trolox equivalents antioxidant capacity/g extract. Conclusion: BEN exhibited a potent antioxidant activity which may be related to the % content of piperine and plumbagin. Moreover, this proposed TLC densitometric method is rapid, reliable, sensitive, and economical for routine analysis of the piperine and plumbagin content in BEN raw materials and its commercial products.