Estimating Herbal Product Authentication and Adulteration in India Using a Vouchered, DNA-Based Biological Reference Material Library.

Abstract

India is considered the 'medicinal garden' of the world, with 8000 medicinal plants of which 960 are commercial species that are traded nationally and globally. Although scientific studies estimate herbal product adulteration as 42-66% in North America, India does not have any published marketplace studies and subsequent estimates of adulteration in an industry facing considerable supply demands. The goal of this project is to provide an initial assessment of herbal product authentication and adulteration in the marketplace in India by (1) developing a biological reference material (BRM) herbal DNA library for Indian herbal species using DNA barcode regions (ITS2 and rbcL) in order to facilitate accurate species resolution when testing the herbal products; and (2) assessing herbal product identification using our BRM library; and (3) comparing the use of our BRM library to identify herbal products with that of GenBank. A BRM herbal DNA library consisting of 187 herbal species was prepared to authenticate the herbal products within India. Ninty-three herbal products representing ten different companies were procured from local stores located at Coimbatore, India. These samples were subjected to blind testing for authenticity using the DNA barcode regions rbcL and ITS2. The results indicate that 40% of the products tested are authentic, and 60% of the products may be adulterated (i.e. contained species of plants not listed on the product labels). The adulterated samples included contamination (50%), substitution (10%) and fillers (6%). Our BRM library provided a 100% Basic Local Alignment Search Tool (BLAST) match for all species, whereas the GenBank match was 64%. Our findings suggest that most Indian herbal medicinal products are essentially mixed with one or a few other herbs that could lessen the therapeutic activity of the main ingredients. We do not recommend the use of GenBank to identify herbal products because the use of this non-curated and/or vouchered database will result in inaccurate species identification. These DNA-based tools provide a scientific foundation for herbal pharmacovigilance to ensure the safety and efficacy of natural drugs. This study provides curated BRMs that will underpin innovations in molecular diagnostic biotechnology, which will soon provide more robust estimates of adulteration and commercial tools that will strengthen due diligence in quality assurance within the herbal industry.