25-Deoxycacospongionolide B and cacospongionolide C, two new terpenoids from the sponge Fasciospongia cavernosa

25-Deoxycacospongionolide B (3), a new bioactive sesterterpene, and a diterpene, cacospongionolide C (4), have been isolated as minor components from the Adriatic sponge Fasciospongia cavernosa. The structures were proposed on the basis of spectroscopic data and defined for the former on the basis of X-ray analysis. Brine shrimp and fish lethalities of 25-deoxycacospongionolide B are reported