Cytotoxic dolabellane diterpenes from the Formosan soft coral Clavularia inflata.

Six new cytotoxic dolabellane diterpenes, (1R,12R)-dolabella-4(16),7,10-triene-3,13-dione (1), (1R*,7R*,8S*,12R*)-dolabella-4(16),10-diene-7,8-epoxy- 3,13-dione (2), (1R*,10R*,11S*,12R*)-dolabella-4(16),7-diene-10,11-epoxy-3,13-dione (3), (1R)-dolabella-4(16),7,11(12)-triene-3,13-dione (4), (1R*,3R*)-3-hydroxydolabella-4(16),7,11(12)-triene-3,13-dione (5), and (1R*,7R*)-7-hydroperoxydolabella-4(16),8(17),11(12)-triene-3,13-dione (6), have been isolated from the Formosan soft coral Clavularia inflata. The structures of compounds 1-6 were determined by 1D and 2D spectral analysis, and their cytotoxicity against selected cancer cells was measured in vitro.