DNA Barcoding of Ayurvedic Herbal Supplements used for the Purported Treatment of COVID-19

Abstract

The SARS-CoV-2 (COVID-19) pandemic was associated with an increased global use of traditional medicines, including Ayurvedic herbal supplements. Because of the growing demand and processed nature of these products, there is an increased risk of adulteration. In order to assess whether the contents of these products are consistent with the label, this study used DNA barcoding to test nine different types of herbal supplements (amla, ashwagandha, cinnamon, ginger, guduchi, tribulus, tulsi, turmeric, and vacha) associated with the Ayurvedic treatment of respiratory symptoms. A total of 54 commercial Ayurvedic herbal products were tested with four barcoding regions (i.e., rbcL, matK, ITS2, and mini-ITS2) using two composite samples per product. The use of the combined loci resulted in the amplification of 85.2% of the products and identification of at least one species in 64.8% of the products (based on the combined results of composite samples). The expected species was detected in 12 of the 54 products. Nine different types of fungal species were identified in 12 products using the ITS2 primers, and it is suspected that these fungal contaminants may originate from the plant sources. Undeclared plant species were detected in 19 products and included species such as rice, pepper, and Ayurvedic herbs not listed on the label. The presence of undeclared plant species may be due to intentional substitution and/or contamination in the growing or processing environment. The matK and rbcL primers were found to be the most effective of the four primer sets used for identification, with at least one composite sample sequenced in 46.3% and 42.6% of products, respectively. Overall, the results of this study indicate that a combination of barcoding regions should be used in DNA vi barcoding to achieve the highest success of sequencing, and that DNA barcoding techniques require further optimization to achieve better identification results in herbal products.