In order to search for novel bioactive compounds, we have investigated the secondary metabolites of the soft corals Nephthea erecta, Lobophytum durum, and Sarcophyton ehrenbergi. Chemical examinations on the organic extracts of N. erecta, have resulted in the isolation of six new sesquiterpenoids (1-6), a new calamenene-type sesquiterpene with a mercaptan group, erectathiol (7), a new tri-nor-eudesmadienone (8), two known sesquiterpenoids (9 and 10), one novel seco-germacrane sesquiterpene (11), three unexpected artificial 19-oxygenated steroids (12-14), as well as twelve new polyhydroxylated steroids (15-26). Furthermore, twelve new cembranolids, durumolides A-L (27-38), three unprecedented hemiketal cembranoids, durumhemiketalolides A-C (39-41), six previously described cembranolids (42-47), together with one known metabolite, peridinin (48), were isolated from the acetone extracts of L. durum. Chemical investigation of S. ehrenbergi, has led to the isolation of a known ceramide (49), two new cerebrosides, sarcoehrenosides A (50) and B (51), along with three previously characterized cerebrosides (52-54). The structures of the isolated metabolites were elucidated through extensive spectroscopic analyses, while the relative stereochemistry of 10 and 44 were further confirmed by X-ray diffraction analyses. Moreover, the absolute configurations of 24, 25, 29, 34, 38, and 43-45 were established by application of modified Mosher¡¦s method. The cytotoxicities, antibacterial activities, anti-inflammatory effects, and inhibition assay of HCMV (human cytomegalovirus) endonuclease activities of these isolated metabolites were evaluated in vitro.

In the course of studying on secondary metabolites from marine organisms, we have investigated the chemical constituents of the soft coral Sarcophyton ehrenbergi collected at San-Hsien-Tai, Taitong County, Taiwan. Chromatographic separation of the organic extracts has led to the isolation of nine new cembrane diterpenes 1¡V9, and a initial natural separation of known cembrane diterpene 10. The chemical structures of pure compounds were determined by spectral (NMR, MS, UV and IR) and physical data, as well as comparison with the spectroscopic data of related chemicals in literature. Moreover, the metabolites 1¡V10 were evaluated in vitro for their cytotoxicity against of A-549 (human lung epithelial carcinoma), HT-29 (human colon adenocarcinoma), and P-388 (mouse lymphocytic leukemia) cells, as well as anti-HCMV activity. Compounds 3, 6, 9, and 10 were shown to exhibit significant cytotoxicity activities against P-388 with ED50 values of 2.7, 3.6, 2.0, and 3.0 £gg/mL, respectively. Compound 1, 2, 3, and 7 exhibited inhibitory activity against anti-HCMV, with EC50 values of 60.0, 46.0, 5.0, and 45.0 £gg/mL.