Megaspinoxide A: New Norterpene Cyclic Peroxide from the Sponge Diacarnus megaspinorhabdosa

Re-investigation of the methanolic extract of the sponge Diacarnus megaspinorhabdosa afforded one new norsesterpene cyclic peroxide megaspinoxide A (2), together with two known compounds sigmosceptrellin B (1) and nebularine (3). The structures of the isolated compounds were established on the basis of one and two dimensional NMR spectroscopic studies (1H, 13C, DEPT, COSY, HMQC, HMBC, and ROESY) as well as, mass spectral analysis. The isolated compounds were evaluated for their cytotoxic and antimicrobial activities.