Investigation on the chemical constituent of a Formosan soft coral Nephthea chabrolii, collected along the coast off Kenting, has led to the isolation of nine marine natural products (1¡V9), including seven new compounds, chabrolosteroids A¡VG (1¡V7), and two known compounds, loliolide (8) and teuhetenone A (9). The structures of 1¡V9 were determined on the basis of spectroscopic analyses, including MS, IR, 1D NMR, and 2D NMR. Cytotoxicities of 1¡V9 against selected cancer cell lines were also measured.

Numerous bioactive secondary metabolites including sesquiterpenoids,diterpenoids, meroditerpenoids, and steroids have been isolated from the soft corals of the genus Nephthea. In order to search for novel bioactive substances from marine organisms, we have investigated the secondary metabolites of the organic extract of the soft coral Nephthea chabrolii collected at San-Hsian-Tai. Chromatographic fractionation of the acetone-soluble has led to the isolation of four 19-oxygenated steroids 1¡V4 and two 19-norergosterols 5, 6, along with twelve known compounds 7¡V18. The structures of these compounds were determined on the basis of their spectroscopic analysis data (1H NMR, 13C NMR, 1H¡V1H COSY, HSQC, HMBC, NOESY, IR, and HRESIMS), physical data and compared with the literature data. The cytotoxicity against of A-549 (human lung epithelial carcinoma), HT-29 (human colon adenocarcinoma), and P-388 (mouse lymphocytic leukemia) cells, and anti-HCMV (human cytomegalovirus) activity of compounds 1¡V6 were evaluated. Metabolites 1¡V6 displayed cytotoxicity against P-388 cell line with ED50 values of 0.93, 1.05, 1.20, 1.74, 1.19, 1.19 £gg/mL. However, none of them exhibited inhibitory activity against HCMV (human cytomegalovirus).

Soft corals belonging to the genus Nephthea have been found to be a rich source of terpenoids and steroids. Chromatographic separation of acetone and CH2Cl2/MeOH extracts of Formosan soft coral Nephthea chabrolii resulted in the isolation of thirteen new steroids, including nine 4£\-methylated steroids (1−6, 8−10), three 19-oxygenated steroids (11−13), and a novel skeleton 19-norsteroid (7). The structures of these metabolites were elucidated by extensive spectral analyses and anti-inflammatory activities were measured in vitro. Compounds 1−2, 4−5, 7−11 and 13 at a concentration of 10 £gM significantly reduce the levels of iNOS (inducible nitric oxide synthase ). Compounds 2, 4, 6−7 and 10−11 at a concentration of 10 £gM also significantly reduce the levels of COX-2 (cyclooxygenase-2). Compounds 2, 4, 7, 10 and 11 can reduce the levels of both iNOS and COX-2. All compounds at a concentration of 10 £gM did not affect the housekeeping £]-actin protein expression.