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Medicinal plants form the basis of traditional medicine health systems and play an important role in meeting primary healthcare needs around the world. At the same time, traditional knowledge on medicinal plants is eroding and deteriorating due to ongoing cultural, ecological and socioeconomical changes. This poses a serious threat to biodiversity-based cultural knowledge and can cause an attrition of leads for drug discovery. On the other hand, it is also important to validate traditional knowledge on plant use using scientific methods to promote or discourage their wider usage. Therefore, the first objective of the thesis is to document traditional knowledge on medicinal plants in Southern India, and validate traditional knowledge of selected medicinal plant using phytochemical methods and biological assays. Paper I aimed to document traditional knowledge on dioecious plants of India. Specifically it addressed the research questions: do folk healers have preference for plants of a specific gender? If so, what are those plants? In addition, do folk healers differentially utilize male and female plant of a particular species for food, medicines or timber? The study found that informants recognize the phenomenon of dioecy in plants, and reported gender preferences for a number of species with respect to uses as timber, food and medicine. Paper II aimed to document the medicinal uses of Canarium strictum Roxb. (Burseraceae) by folk healers in India, and to investigate the chemical constituents and biological activities of the resin and stem bark. Our results revealed the presence of α-amyrin and β-amyrin as the major compounds in the resin. Whereas gallic acid, methyl gallate, scopoletin, 3,3'-di-O-methylellagic acid 4-O-α- arabinofuranoside, elephantorrhizol (3,3',4',5,6,7,8-heptahydroxyflavan) and procyanidins were isolated from the bark methanol extract. It is noteworthy that the finding of elephantorrhizol in C. strictum is of chemotaxonomic interest as it is the first report from the family Burseraceae. Furthermore, radical scavenging and 15-lipoxygenase inhibitory activities were tested in resin and bark extracts, but no toxicity towards Artemia salina nauplii was found. Similarly, dose dependent inhibition of NO production was observed in resin and dichloromethane bark extracts. Traditional medicine based herbal products have gained increasing popularity in developing countries as complementary therapies. However, herbal products are prone to contamination, adulteration and substitution, and this raises quality and safety concerns for the public. Therefore, the second part of thesis focused on molecular authentication of raw herbal drugs and marketed herbal products using NMR spectroscopic and DNA methods. The aim of Paper III was to assess the adulteration of morphologically similar samples of Garcinia using DNA barcoding, and to quantify the content of (−)-hydroxycitric acid and (−)-hydroxycitric acid lactone in raw herbal drugs and Garcinia food supplements using NMR spectroscopy. Our DNA barcoding study revealed that there was no adulteration in raw herbal drugs of Garcinia. Whereas, analysis of ten Garcinia food supplements revealed a large variation in the content of (−)-hydroxycitric acid content per capsule or tablet. Paper IV aimed to test the composition and fidelity of Ayurvedic products marketed in Europe using DNA metabarcoding. Our analysis revealed that the fidelity for single ingredient products was 67%, and the overall ingredient fidelity for multi ingredient products was 21%, and for all products 24%.

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.