Medicinal plants such as Cassia, Senna, and Chamaecrista (belonging to the family Fabaceae) are well known for their laxative properties. They are extensively used within indigenous health care systems in India and several other countries. India exports over 5000 metric tonnes per year of these specific herbal products, and the demand for natural health product market is growing at approximately 10-15% annually. The raw plant material used as active ingredients is almost exclusively sourced from wild populations. Consequently, it is widely suspected that the commercial herbal products claiming to contain these species may be adulterated or contaminated. In this study, we have attempted to assess product authentication and the extent of adulteration in the herbal trade of these species using DNA barcoding. Our method includes four common DNA barcode regions: ITS, matK, rbcL, and psbA-trnH. Analysis of market samples revealed considerable adulteration of herbal products: 50% in the case of Senna auriculata, 37% in Senna tora, and 8% in Senna alexandrina. All herbal products containing Cassia fistula were authentic, while the species under the genus Chamaecrista were not in trade. Our results confirm the suspicion that there is rampant herbal product adulteration in Indian markets. DNA barcodes such as that demonstrated in this study could be effectively used as a regulatory tool to control the adulteration of herbal products and contribute to restoring quality assurance and consumer confidence in natural health products.

Saraca asoca (Roxb.) Willd, commonly known as "Asoka" or "Ashoka," is one of the most important medicinal plants used in raw herbal trade in India. The bark extracts of the tree are used in the treatment of leucorrhea and other uterine disorders besides also having anti-inflammatory, anti-bacterial, anti-pyretic, anti-helminthic, and analgesic activity. The indiscriminate and rampant extraction of the wood to meet the ever-increasing market demand has led to a sharp decline in naturally occurring populations of the species in the country. Consequently, the species has recently been classified as "vulnerable" by the International Union for Conservation of Nature (IUCN). Increasing deforestation and increasing demand for this medicinal plant have resulted in a limited supply and suspected widespread adulteration of the species in the raw herbal trade market. Adulteration is a serious concern due to: (i) reduction in the efficacy of this traditional medicine, (ii) considerable health risk to consumers, and (iii) fraudulent product substitution that impacts the economy for the Natural Health Product (NHP) Industry and consumers. In this paper, we provide the first attempt to assess the extent of adulteration in the raw herbal trade of S. asoca using DNA barcoding validated by NMR spectroscopic techniques. Analyzing market samples drawn from 25 shops, mostly from peninsular India, we show that more than 80 % of the samples were spurious, representing plant material from at least 7 different families. This is the first comprehensive and large-scale study to demonstrate the widespread adulteration of market samples of S. asoca in India. These results pose grave implications for the use of raw herbal drugs, such as that of S. asoca, on consumer health and safety. Based on these findings, we argue for a strong and robust regulatory framework to be put in place, which would ensure the quality of raw herbal trade products and reassure consumer confidence in indigenous medicinal systems. Graphical Abstract DNA barcoding and NMR spectroscopy-based assessment of adulteration in Saraca asoca.

Garcinia L. (Clusiaceae) fruits are a rich source of (−)-hydroxycitric acid, and this has gained considerable attention as an anti-obesity agent and a popular weight loss food supplement. In this study, we assessed adulteration of morphologically similar samples of Garcinia using DNA barcoding, and used NMR to quantify the content of (−)-hydroxycitric acid and (−)-hydroxycitric acid lactone in raw herbal drugs and Garcinia food supplements. DNA barcoding revealed that mostly G. gummi-gutta (previously known as G. cambogia) and G. indica were traded in Indian herbal markets, and there was no adulteration. The content of (−)-hydroxycitric acid and (−)-hydroxycitric acid lactone in the two species varied from 1.7% to 16.3%, and 3.5% to 20.7% respectively. Analysis of ten Garcinia food supplements revealed a large variation in the content of (−)-hydroxycitric acid, from 29 mg (4.6%) to 289 mg (50.6%) content per capsule or tablet. Only one product contained quantifiable amounts of (−)-hydroxycitric acid lactone. Furthermore the study demonstrates that DNA barcoding and NMR could be effectively used as a regulatory tool to authenticate Garcinia fruit rinds and food supplements.

Traditional medicines are widely traded across the globe and have received considerable attention in the recent past, with expectations of heightened demand in the future. However, there are increasing global concerns over admixture, which can affect the quality, safety, and efficacy of herbal medicinal products. In this study, we aimed to use DNA metabarcoding to identify 39 Thai herbal products on the Thai National List of Essential Medicines (NLEM) and assess species composition and admixture. Among the products, 24 samples were in-house-prepared formulations, and 15 samples were registered formulations. In our study, DNA metabarcoding analysis using ITS2 and rbcL barcode regions were employed to identify herbal ingredients mentioned in the products. The nuclear region, ITS2, was able to identify herbal ingredients in the products at the genus- and family-levels in 55% and 63% of cases, respectively. The chloroplast gene, rbcL, enabled genus- and family-level identifications in 58% and 73% of cases, respectively. In addition, plant species were detected in larger numbers (Family identified, absolute %) in registered herbal products than in in-house-prepared formulations. The level of fidelity increases concerns about the reliability of the products. This study highlights that DNA metabarcoding is a useful analytical tool when combined with advanced chemical techniques for the identification of plant species in highly processed, multi-ingredient herbal products.