Cytotoxic Sesterterpenoids Isolated from the Marine Sponge Scalarispongia sp.

Eight scalarane sesterterpenoids, including four new compounds, were isolated from the marine sponge Scalarispongia sp. The structures of the new compounds were elucidated by 2D-NMR and HRMS analyses. All of the isolated compounds, with the exception of 16-O-deacetyl-12,16-epi-scalarolbutanolide, showed significant in vitro cytotoxicity (GI50 values down to 5.2 mu M) against six human cancer cell lines.