4-ACETYLAPLYKURODIN-B AND APLYKURODINONE-B, 2 ICHTHYOTOXIC DEGRADED STEROLS FROM THE MEDITERRANEAN MOLLUSK APLYSIA-FASCIATA

Two ichthyotoxic lactones, 4-acetylaplykurodin B [1] and aplykurodinone B [2], were isolated from the external parts of the body of the mollusk Aplysia fasciata. Their structures, determined by spectroscopic and chemical means, are closely related to aplykurodin B [3] previously isolated from Aplysia kurodai. The interconversion of delta- and gamma-lactones in the aplykurodin derivatives has been also investigated.