Studies On Five South China Sea Sponges: Chemistry And Bioactivities

Natural materials are prolific source of secondary metabolites with diverse structures and biological properties. In the processes of our searching for bioactive compounds, we have chemically investigated five species of marine sponges collected along the coast of South China Sea. All the compounds have been evaluated for biological activities and studied on the roles in chemecology.From these marine sponges,55 compounds were isolated, including 21 sesquiterpenoids,4 diterpenoids,6 steroids,11 3-alkylpyridines,2 polyunsaturated amino ketones,4 long-chain compounds and 7 compounds with other type of skeletons, were isolated by repeated chromatography. Their structure and relative stereochemistry were elucidated on the basis of extensive spectroscopic analysis and chemical methods, and by comparison of the data with those reported data in the literature. In these compounds,13 new compounds were identified. Some of them were found to show significant bioactivities on specific bioassay models.From the acetone extracts of sponge LS-340 and YAL-64, we obtained 21 sesquiterpenes containing unusual nitrogenous functional groups, such as isothiocyanate, formamide, isonitrile, and thiocyanate and 4 kalihinol diterpenes. In these compounds,4 new compounds were identified. It is interesting to note that a series of N-containing sesquiterpenes were isolated, from Hainan nudibranches Hexabranchus sangueneus and Phyllidiella pustulosa implied that the nudibranche might acquire the metabolites by dietary transfer from these sponges.From the acetone extracts of sponge LS-58, WZ-33 and WZ-9 we obtained 13 long-chain alkaloids. In these compounds,11 3-alkylpyridines and 2 polyunsaturated amino ketones were identified. Although 3-alkylpyridine alkaloids with side chains terminating in an aldehyde group have been reported from opisthobranch mollusks, compound 4-4 is the first report from a sponge.All the compounds have been evaluated for biological activities, some of them exhibited broad bioactivities such as 2-6,2-11,3-3,3-4,3-9 and 3-10 showed inhibitory activity to A-549 and 4-1,4-3,4-7,4-8 and 4-10 exhibited moderate inhibitions of voltage gated potassium channels.