DNA barcoding and NMR spectroscopy to check for adulteration in Garcinia species used in herbal medicines
Globalization in the trade of herbal products and an expanding commodity market have resulted in widespread consumption of medicinal plants as drugs, cosmetics and food supplements, both in developing and developed countries. Quality, safety and efficacy of herbal medicines are key requirements for public health and a major concern for regulatory authorities.
India is the second largest exporter of medicinal plants and exports mainly in the form of dried plant products. Several reports suggest that only 10% of medicinal plants traded in India are being cultivated. Growing commercial demands for raw drug products increases the incentive for adulteration and substitution in the medicinal plants trade. Such adulteration can threaten consumer health, damage consumer confidence, and generally lower the trade value of such products.
Garcinia L. (Clusiaceae) is a genus of evergreen polygamous trees and shrubs comprising 400 species with a pan-tropical distribution. Thirty-five species occur in India, of which 17 species are reported from the Western Ghats. Garcinia fruits are widely collected and commercially exploited for their medicinal value. The fruit rinds of Garcinia indica (Thouars) Choisy (Kokum) are traditionally used to treat rheumatic pains, bowel complaints, haemorrhoids, ulcers, inflammations, sores, dermatitis, dysentery and to prevent hyperhidrosis. It is also used for cooking in India.
Garcinia L. (Clusiaceae) fruits are a rich source of hydroxycitric acid and have gained considerable attention as an anti-obesity agent and a popular weight loss food supplement. This study assessed adulteration of morphologically similar samples of Garcinia using DNA barcoding, and used NMR spectroscopy to quantify the content of hydroxycitric acid in raw herbal drugs and Garcinia food supplements.
DNA barcoding revealed that mostly Kudam Puli and Kokum were traded in Indian herbal markets, and there was no adulteration. The content of hydroxycitric acid in the two species varied from 1.7% to 16.3%. 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 tablet. Furthermore the study demonstrated that DNA barcoding and NMR could be effectively used as a regulatory tool to authenticate Garcinia fruit rinds and food supplements.