Authentication of the market samples of Ashwagandha by DNA barcoding reveals that powders are significantly more adulterated than roots.

ETHNOPHARMACOLOGICAL RELEVANCE

Ashwagandha, also known as Indian Ginseng, is a highly traded medicinal plant, which is used in Ayurveda, Siddha and Unani systems of medicine to improve cognitive function, decrease inflammation, and to counter the ill-effects of aging. Withanolide A and Withaferin A from Ashwagandha were shown to improve immunity and have anti-cancer property, respectively.

AIM OF THE STUDY

Here, we aimed to create reference DNA barcodes for W. somnifera and to authenticate root and powder samples of Ashwagandha collected from markets.

MATERIALS AND METHODS

Three plant specimen of W. somnifera were collected, and reference DNA barcodes were generated using rbcL, matK, trnH-psbA, and ITS2 DNA barcode markers. Market samples in the form of root (n = 33) and powder (n = 70) were collected and authenticated using ITS2 and trnH-psbA DNA barcodes.

RESULTS

Genomic DNA was successfully isolated from all plant specimens and market samples. DNA barcoding showed that 77% of samples were authentic. About 22% of non-authentic samples were powder samples and only 1% were root samples. Among the non-authentic samples, 18% were completely substituted with single species (Mucuna pruriens (L.) DC., Trigonella foenum-graceum L., or Senna auriculata (L.) Roxb.) and 82% were mixed samples containing more than one species. About 63% of the mixed samples contained Ashwagandha as the major ingredient. Furthermore, we identified that six taxonomically divergent plant species from four families were present as adulterants in the mixed samples.

CONCLUSION

DNA barcoding revealed that botanical adulteration in the market samples of Ashwagandha is significant. Powder samples are more prone to adulteration than root samples. The adulterated samples contained plant material that is not related to Ashwagandha, which warrants strict quantity control and market surveillance to derive the true medicinal benefits of this medicinal plant.