Sesquiterpene Furans and Thiosesquiterpenes from the Nudibranch Ceratosoma brevicaudatum

Six furanosesquiterpenes have been isolated from an Australian nudibranch, Ceratosoma brevicaudatum, and their structures were determined by spectral analysis. The metabolites include the known terpenes dehydrodendrolasin [1], dehydrolasiosperman [3], and thiofurodysinin acetate [7]. The remaining metabolites were determined to be an unreported cis isomer 2 of dehydrodendrolasin, (methylthio) furodysinin [4], and dithiofurodysinin disulfide [5], derivatives of thiofurodysinin acetate that had been isolated earlier from a sponge. 13C-nmr data were obtained for all compounds.