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Two new antifungal and cytotoxic cyclic-peroxide-containing acids, 1 and

3, were isolated from a marine sponge, Plakortis angulospiculatus, which was collected by scuba off the coast of Venezuela. The structures were elucidated through spectral and chemical analysis of the corresponding methyl esters, 2 and 4. The acids are potent cytoxic and antifungal agents although their esters are only cytotoxic.

In addition to the common steroidal peroxides (1), numerous other cyclic peroxides have been reported from marine organisms (2, 3). Most are derived from sponges and are car boxy-containing products of terpenoid (4—7) or polyketide (8—12) biosynthesis. Examples are the branched chain esters, plakortin (9) and epiplakortin (11); the free acid, plakortic acid (12); and the straight-chain metabolites, eg, chondrillin (5) and the re-lated compounds from Plakortis lita (13). These compounds exhibit antimicrobial ac …