We have searched the bioactive metabolites from the wild-type and cultured soft corals Sinularia flexibilis. This study led to the isolation of fifteen natural products (1¡V15), including four new metabolites (1¡V4), flexibilisolide A (1), flexibilisin A (2), quercifomolide D (3) and quercifomolide B (4) along with eight known compounds (5¡V12) from the wild-type soft coral S. flexibilis, and three new metabolites (13¡V15), flexibilisolide B (13), flexibilisin B (14), flexibilisquinone (15) along with four known compounds (9¡V12) from the cultured soft coral S. flexibilis. The structures of metabolites 1¡V15, including their stereochemistries, have been established by detailed spectroscopic analyses and by comparison with the related physical and spectral data from other known compounds. The relative configuration of metabolite 4 was further confirmed by X-ray single-crystal diffraction analysis. Furthermore, the absolute configuration of 4 was determined by a modified Mosher¡¦s method. The cytotoxicity of 1¡V15 against the growth of human tumor cell lines, including cervical epitheloid (Hela), laryngeal (Hep 2), medulloblastoma (Daoy) and breast (MCF-7) carcinoma cells was studied. The results showed that only compounds 7, 9 and 11 exhibited moderate cytotoxicities against the tested cell lines. Furthermore, compounds 1, 6, 8, 9, 11¡V13 and 15 were found to significantly inhibit the accumulation of the pro-inflammatory iNOS protein in the LPS-stimulated RAW264.7 macrophage cells at 10 £gM. At the same concentrations, compounds 11 and 12 also could significantly inhibit the accumulation of the pro-inflammatory COX-2 protein.

In order to discover bioactive secondary metabolites, we have studied the chemical constituents from the organic extracts of soft coral Sinularia flexibilis. This study had led to the isolation of eighteen natural compounds 1¡V18, including seven new cembrane-type diterpenoids, flexibilisolides C¡VG (1, 2, 3, 6, 7), flexiblilisin C (5), 11,12-secoflexibillin (4) along with eleven know compounds. The structure of compounds 1¡V18 were established by detailed spectral data analysis (IR, MS, 1D, 2D NMR) and by comparison of the spectral data with those of the related known compounds. The cytotoxicity of compounds 1¡V6, 8¡V14, 16¡V18 against the Hela (human cervical epitheloid carcinoma), SK-Hep1 (human liver carcinoma), and B16 (human melanin carcinoma) tumor cell lines were screened. Compounds 1, 9, 12, and 13 showed moderate activity toward the Hela and SK-Hep1 tumor cells. Compound 12 also showed moderate activity toward the B16 cells, and compound 14 showed activity toward the Hela cells. On the other hand, compounds 1, 9, 13, and 17 were found to show significant activity against the accumulation of the pro-inflammatory iNOS and COX-2 protein at 10 £gM. Compounds 2¡V4, 7, 8, 10, 14, 16 were found to show activity against the accumulation of the pro-inflammatory iNOS protein at 10 £gM.

Corals are the dominant species of the coral reefs. The diversity of species is classified by traditional morphological traits, especially relied on the calcious deposits-sclerites. The formation of sclerites may be affected by the environmental conditions; therefore, some controversies may exist. The ambiguities may be clarified with molecular approaches. Five soft coral species, Lobophytum pauciflorum, Sinularia leptoclado, Sinularia flexibilis, Sarcophyton sp., Nephthea erecta were chosen for this study. The total mitochondrial DNA sequences were determined by PCR and primer walking. The genome contains 18562 bp, 18732 bp, 18752 bp, 18806 bp, 18716 bp separately, which harbors 14 protein-coding genes (ATP6¡BATP8¡BCOI¡BCOII¡BCOIIII¡BCYTB¡BND1¡BND2¡BND3¡BND4¡BND4L¡BND5¡BND6¡BMSH), 2 rRNA and only 1 tRNA genes. The phylogenetic relationship of alcyonacea corals were analyzed and compared with published sequences. The possibility of using a short ¡§DNA bar-code sequence¡¨ of the mitochondria as an alternative for species identification may be feasible. We found the short DNA signature sequences for these five corals. They may speed up the identification of corals in the long run.