Excavatolides F-M, new briarane diterpenes from the gorgonian Briareum excavatum

Eight new briarane-type diterpenes, excavatolides F-M (1-8), have been isol ated from the gorgonian Briareum excavatum. The structures and relative ste reochemistry of these compounds were established by spectral analysis and c hemical methods. The cytotoxicity of these compounds toward various cancer cell lines has also been determined.