NOVEL CYTOTOXIC DITERPENES, EXCAVATOLIDES-A-E, ISOLATED FROM THE FORMOSAN GORGONIAN BRIAREUM-EXCAVATUM

The chemistry of Briareum excavatum, a Formosan gorgonian coral, was i nvestigated. This study has led to the isolation of five novel marine natural products, excavatolides A-E (1-5), together with brianolide (6 ). The structures of the above compounds were established by spectral and chemical methods. The relative configuration of excavatolide B (2) was further confirmed by a single-crystal X-ray structure analysis. C ytotoxicity of these compounds toward various cancer cell lines also i s described.