||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 fifteen natural compounds 1–15, including five new cembranolide-related compounds, Flexibilisin D (1), secoflexibilisolides A and B (2 and 3), flexibilisolides H and I (4 and 5) along with ten know compounds from S. flexibilis. The structures and relative configurations of all metabolites had been established by detailed spectroscopic analysis including 1D and 2D NMR (1H, 13C, 1H–1H COSY, HSQC, HMBC and NOESY) data in association with MS experiments.|
The cytotoxicity of compounds 1, 3–16 against the P-388 (murine leukemia), K-562 (human erythro myeloblastoid leukemia) and HT-29 (human colon carcinoma cells) were assayed, and compounds 7, 10, 11 showed significant cytotoxicity against the P-388 cell line with IC50 values of 24.1, 16.2 and 16.0 μM, respectively. On the part anti-inflammation assay, compound 11 were found to show inhibiting activity.