Cytotoxic diterpenoids from the hybrid soft coral Sinularia maxima x Sinularia polydactyla.

Chemical investigation of the hybrid soft coral Sinularia maxima x Sinularia polydactyla yielded four new cembranolide diterpenes (1-4), the norcembranoid 5-episinuleptolide (5), and two known sesquiterpenes. The structures and configurations of the new compounds were determined by spectroscopic techniques and comparison of NMR data with those of related metabolites. Compound 3 shows strong cytotoxicity on the breast cancer SK-BR3 cell line and cervix cancer HeLa and HeLa-Apl cell lines with GI(50) values of 0.039, 0.48, and 0.56 microM, respectively.