Diterpenoids from the Hainan Soft Coral Sinularia parva

Two new cembrane diterpenes, sinulaparvalides A and B (1 and 2, resp.), which contain an intriguing seven-membered lactone moiety, along with the four known related cembranoids 3-6, were isolated from the Hainan soft coral Sinularia parva. The structures of compounds I and 2 were established by spectroscopic methods, mainly on the basis of 2D-NMR techniques, and were confirmed by single-crystal X-ray diffraction analysis. The in vitro cytotoxic activities of these compounds were tested on human colon carcinoma (HCT-116), human promyelocytic leukemia (HL-60), and human lung carcinoma (A-549) tumor cell lines.