An Unprecedented Cembranoid with a Novel Tricyclo[9.3.0.02,12]tetradecane Skeleton and Related Diterpenes from the Soft Coral Sarcophyton cinereum

Abstract Cinerelolide (1) with an unprecedented tricyclo[9.3.0.02,12]tetradecane scaffold fused with a seven-membered lactone ring, and a new sarsolenone derivative, 11-deoxo-11α-hydroxysarsolenone (2), were isolated from the Formosan soft coral Sarcophyton cinereum. Their structures were rigorously determined by spectroscopic study, chemical transformation, and computational approach. Also, the structures of sarsolenone and 7-deacetylsarsolenone were revised in this work. Some of the isolates were shown to exhibit cytotoxicity toward a limited panel of cancer cell lines.