Cytotoxic cyclic norterpene peroxides from a Red Sea sponge Diacarnus erythraenus.

Investigation of the lipophilic extract of the Red Sea sponge Diacarnus erythraenus revealed one new norsesterterpene cyclic peroxide, aikupikoxide A (1), three new norditerpene cyclic peroxides, aikupikoxide B-D (2-4), and the known norterpene peroxides muqubilin and nuapapuin A methyl ester. In addition, a new sesquiterpene, O-methyl guaianediol, was isolated. Their structures were determined by means of spectroscopic methods. The cytotoxic activities for the isolated compounds have been reported.