A new cacospongionolide derivative from the sponge Fasciospongia cavernosa

Cacospongionolide F (4a), a new bioactive cacospongionolide-related sestert erpene, has been isolated from the Northern Adriatic sponge Fasciospongia c avernosa. The structure was proposed on the basis of spectroscopic data and chemical transformations. The absolute configuration was established using the modified Mosher's method. A molecular mechanics study of the dehydrode calin ring explained the observed differences in dynamic behavior between c acospongionolide F and mamanuthaquinone, a related compound. Antimicrobial activity, brine shrimp and fish lethalities of this new compound are report ed.