In our ongoing research for secondary metabolites from the Formosan soft corals, six sesquiterpenoids namely GN76-9-1 (1), GN76-10-3 (2), GN76-12-6-10-1 (3), GN76-25-1 (4), GN76-25-5 (5), and GN76-30-5 (6) were isolated from Lemnalia flava (GN76). Among these secondary metabolites, compound 1 possessing a ylangene-type skeleton is a new natural product. Chromatographic separation of the extracts of the Formosan soft coral Efflatounaria tottoni yielded one known compound, GN79-11-3 (7), having an alcyonolide-type structure. In addition, two known germacrane-type sesquiterpenoids, GN82-11-4-2-15 (8) and GN82-16-5-6-25 (9), were isolated from the extracts of the Formosan soft coral Klyxum simplex (GN82). The structures of compounds 1 possessing a ylangene-type skeleton is a new natural product. Chromatographic separation of the extracts of the Formosan soft coral Efflatounaria tottoni yielded one known compound, GN79-11-3 (7), having an alcyonolide-type structure. In addition, two known germacrane-type sesquiterpenoids, GN82-11-4-2-15 (8) and GN82-16-5-6-25 (9), were isolated from the extracts of the Formosan soft coral Klyxum simplex (GN82). The structures of compounds 1-9 were elucidated by extensive spectral analyses. The anti-inflammatory and neuro-protective activities of these compounds were measured in vitro. Compound 2 showed more specific inhibition against the increase of the pro-inflammatory iNOS and COX-2 proteins of LPS-stimulated RAW264.7 macrophage cells. Compound 8 also reveals more specific neuro protective activity to human neuroblastoma cells SH-SY5Y.

In the study on the chemical constituents from the Formosan marine organisms, four steroids, including three cholanic acid type metabolites, deoxycholic acid 3,12-diacetate (1), deoxycholic acid 3,12-diacetate-24-methyl ester (2), 3£\,7£\,12£\-triacetoxy-5£]-cholanic acid (3), and a principal steroid, gorgosterol (4), were isolated from the soft coral Klyxum simplex, collected at southern Taiwan coast. The structures of steroids 1-4, were elucidated by extensive spectroscopic methods, particularly in 1D and 2D NMR experiments. To best of our knowledge, there is no report on the isolation of cholanic acid type steroids from any marine source. Based on detailed analysis, steroid 2 was found to be a new natural product and this is the first time to isolate steroid 1 from natural resource. Furthermore, two known isoquinoline quinones, mimosamycin (5) and O-demethylrenierone (6) and a known steroid,24,28-didehydroaplysterol (7), were obtained from an Indonesian sponge belonging to the genus Halichondria (Halichondriidae). The structures of metabolites 5-7 were determined by spectral data analysis and by comparison with the spectral and physical data of other known compounds. The antimicrobial activity of compounds 1-7 against Staphylococcus aureus were assayed. It was found that compounds 1, 5 and 6 showed antimicr- obical activity toward Staphylococcus aureus.

In order to search for bioactive compounds, we have studied the chemical constituents from the organic extracts of one soft corals Klyxum simplex and two gorgonians Subergorgia mollis and Briareum excavatum. This study had led to the isolation of twenty-seven natural compounds 1¡V27, including nineteen new eunicellin¡Vtype diterpenoids, simplexins A¡VS (1¡V19) from K. simplex, one new steroid 11£\,15£\-diacetoxy-17£]-pregna-4,20- dien-3-one (20) along with one known compound 17£]-pregna-4,20-dien-3- one (21) from S. mollis, and six new briarane¡Vtype diterpenoids briaexcavatolides Q (22), S¡VV (23-26) and W (27) from B. excavatum. The structure of these compounds were established by the detailed spectroscopic analysis (IR, MS, 1D¡B2D NMR) and by comparison of the physical and spectral data with those of the related known compounds. The absolute configuration of 1 was determined by using a modified Mosher's method. The cytotoxicity of compounds 1¡V6, 9, 13¡V15 against the MCF-7 (human breast adenocarcinoma), Hep2 (human laryngeal carcinoma), Daoy (human medulloblastoma), and Hela (human cervical epitheloid carcinoma) cancer cell lines were determined. Compounds 1, 4 and 14 showed weak inhibition against the growth of MCF-7, Hep2 and Daoy, but did not inhibit the growth of Hela cells. Compound 5 exhibited a weak cytotoxicity against the growth of MCF-7, Hep2, Hela and Daoy cells. In addition, the activity of compounds 1¡V6, 9, 13¡V15 to inhibit the pro-inflammatory iNOS and COX-2 protein expression in LPS-stimulated RAW264.7 macrophage cells was estimated. Compound 5 showed the best anti-inflammatory activity among the all tested compounds.