Plenary Speaker

Natural Products -- An Exciting Source of New Drugs and Pharmacophores
Atta-ur-Rahman and M. Iqbal Choudhary
Pakistan


Two third of the world’s population relies on natural remedies for primary health care and the global annual sale of botanicals is over $ 80 billion. These two statistics reflect the importance of natural products in health and economy. Access to reliable ethnomedicinal knowledge, combined with modern tools of research such as LC-MS/MS, LC-NMR, LC-MS/NMR, etc., and high-throughput screening protocols are greatly facilitating the process of drug discovery from natural sources.

We have already investigated several hundred terrestrial and marine plants for their chemical and biological significance and isolated and identified over 2000 compounds of which some 600 turned out to be new and novel compounds with potential to be developed as medicines. In order to optimize the chances of finding novel leads, extensive primary biological screening and activity-guided fractionation and purification were carried out. State-of-the-art spectroscopic techniques, especially modern multi-dimensional NMR techniques, were utilized to elucidate the structures of bioactive natural molecules, rapidly and accurately. The bioassay protocols include antibacterial, antifungal, cytotoxicity, phytotoxicity, insecticidal, antileishmanial, antioxidant and enzyme inhibition activities. The results so far have been truly exciting as we have identified several new classes of potent cholinesterase, urease, phosphodiesterase, glucuronidase, and prolyl endopeptidase inhibitors. A large number of antioxidant secondary metabolites have also been identified. In the majority of cases, chemical and microbial derivatizations were carried out to study the structure-activity relationships.

A selection of these results illustrated by their potential application to treat diseases such as epilepsy will be presented. Synthetic approaches to bioactive anti-cancer compounds will also be presented.