Drug discovery and herbal drug development: A special focus on the anti-diarrheal plants of Bangladesh

Abstract

Bangladesh, although being a small country, contains more than 5000 floral species of which around 1500 are now recognized to be used as medicinal plants. Such plants are used in the classical formats of traditional medicine like Ayurveda, Unani, and homeopathy; and by folk medicinal practitioners, folk herbalists, and tribal medicinal practitioners; and in home remedies. Since these plants have a history of usage dating back at least 3500 years ago, the plants present a potentially rich source for the discovery of lead compounds and novel drugs. This is important because changes in lifestyle (leading to disorders like metabolic syndrome, diabetes, and hypertension) and emergence of new diseases and drug-resistant vectors are causing a dire necessity for discovery of new drugs. A number of plants of Bangladesh have already been recognized to contain compounds of therapeutic importance. These include curcumin from Curcuma longa, withanolide from Withania somnifera, arjunolic acid from Terminalia arjuna, reserpine from Rauwolfia serpentina, and vincristine and vinblastine from Catharanthus roseus, to name only a few. This review will attempt to explore the drug discovery potential of some anti-diarrheal medicinal plants of Bangladesh based on their reported pharmacological activities and known phytochemicals. Diarrhea is extremely common in Bangladesh, particularly in rural children, rotavirus being one of the main causative agents. Where possible, we will use molecular docking studies to determine the possible efficacy of a given phytochemical against a target rotavirus protein.