Identification of Bioactive Secondary Metabolites from Marine Organisms

Abstract

Marine natural products have been a potential sources of drug leads and new drugs. More than 70% of earths surface is covered with the ocean and diverse marine organisms inhabit the ocean. Marine organisms living in the diverse environment have inspired researchers to identify unprecedent marine natural products which could be developed into therapeutics. Furthermore, technical improvements have accelerated exploration of the marine environment and development of the marine natural product chemistry. In the course of our search for secondary metabolites from marine microorganisms, we obtained two novel compounds from CNQ675 strain (Nocardiopsis sp., La Jolla, California, USA) which showed potent inhibitory activity on nitric oxide synthesis. Their structures were elucidated on the basis of 1H, 13C, 2D NMR, MS, UV and IR analysis. Four known sesquiterpenoids and diketopiperazines were isolated from Korean marine sponge derived fungi, Aspergillus versicolor, using bioassay-guided fractionation. Their structures were elucidated by the interpretation of 1H, 13C, 2D NMR, MS and UV spectroscopic data. These compounds exhibited significant anti-inflammatory activity by inhibiting the production of PGD2, LTC4. Three known degraded sterol derivatives were isolated from a Korean marine sponge Homaxinella sp. The crude extract exhibited significant antibacterial activity selectively against Gram-positive strain (Staphylococcus aureus CCARM 0205).