NOVEL VERRUCOSINS FROM THE SKIN OF THE MEDITERRANEAN NUDIBRANCH DORIS-VERRUCOSA

Nine new diterpenoid acid glycerides (4-12) have been isolated, togeth er with the previously reported 13 and 14, from the skin extract of th e Mediterranean nudibranch Doris verrucosa. The structure and the rela tive stereochemistry of the new metabolites were established by interp retation of spectral data. Absolute stereochemistry of the diterpenoid part was suggested by biogenetic considerations as well as by compari son of CD profiles of 4-12 with those of verrucosin-A (2) and -B (3), previously isolated from the same mollusc. The S absolute configuratio n of C-2' of the glyceryl moiety was determined by chemical methods fo r verrucosin-3 (6), as already reported for 2 and 3, and suggested to be the same for all other verrucosins. (C) 1997, Elsevier Science Ltd.