Two new sarasinosides from marine sponge Petrosia nigricans.

Two new sarasinosides designated as 5,8-epoxysarasinoside (1) and 8,9-epoxysarasinoside (2) and four known sarasinosides were isolated from marine sponge Petrosia nigricans, collected off the coast of Lipata, Surigao City, Philippines (9°49' North, 125°27' East). The structures were determined through extensive 2D NMR spectroscopy and HRMS. Both compounds exhibited low cytotoxicity against the HCT116 (colon) and A549 (lung) cancer cell lines.