ABSTRACT:
Natural products have been, and continue to be, an invaluable source of novel drug compositions for the treatment of various diseases. Of the 1073 small molecules approved as drugs between 1981 and 2010, 59 (6%) are compositions Containing natural products. Another 299 (28%) are derived from natural products, 177 (16%) are synthetic molecules that are derived directly from natural products and 146 (14%) are synthetic structures that are modeled on a natural product. Bangladesh is a rich repository of medicinal plants, many of which are widely used in the Ayurvedic, Unani, Herbal and echer traditional systems of medicines. The study programs were initiated to investigate some of the traditionally used medicinal plants of Bangladesh, including Corypha taliera, the only living wild species of tali palm for the discovery of novel drug candidates. Several microbial strains and marine samples were also studied for anti-cancer and HIV-inhibitory compounds. The concentrated extractives of properly authenticated samples were subjected to repeated separation and purification processes, including HPLC. The structures of the purificd molecules were elucidated by extensive spectroscopic studies and chemical derivatization, when required. The extractives were also subjected to appropriate assay techniques to establish the bioactivities. We have investigated over 60 medicinal plants and several microbial strains that have resulted in the isolation and characterization of 150 compounds, including 50 new molecules. The crude extractives and several purified molecules demonstrated statistically significant inhibition of growth of microorganisms as well as cytotoxicity, antioxidant and antidiabetic activities. On the other hand, the marine samples have yielded peptides, depsipeptides and macrolides with potential anti-HIV and anti-neoplastic activities. Our studies have resulted in the isolation and characterization of numerous chemically unique and biologically interesting secondary metabolites. Some of these results are in conformity with the traditional uses of the investigated plants.