ABSTRACT
Natural products have been discovered from a wide variety of living organisms such as plants, microorganisms, marine lives, and insects; and many of them showed fascinating structures or remarkable biological activities. In fact, 60% of anticancer drugs and 75% of anti-infective drugs developed between 1981 and 2002 are natural products themselves or derivatives developed from natural products (Newman et al., 2003). Substances such as cyclosporine, FK506, mevastatin, micafungin, and avermectin are derived from natural products produced by microbes; and they are major examples that gave a signi˜cant impact to basic and clinical researches (Ganesan, 2008). Furthermore, natural products not only contribute greatly to the development of medical drug and agrichemical discovery researches etc., but also play an important role as bioprobes for elucidating life phenomena, studies of which have rapidly advanced recently (Osada, 2000). Thus, compounds derived from natural products are, quite simply, repository of drug types with limitless possibilities in the ˜eld of drug discovery research.
