Cytotoxic cyclic norterpene peroxides from a Red Sea sponge Diacarnus erythraenus

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