CYTOTOXIC TRITERPENES FROM A MARINE SPONGE, STELLETTA SP

Bioassay-guided fractionation of an extract of a marine sponge, Stelle tta sp., has led to the isolation and characterization of four new cyt otoxic isomalabaricane triterpenes, named stellettins C (1), D (2), E (3), and F (4). Three known triterpenes (5-7) were also isolated from the same extract. The most sensitive of the tested cell Lines (e.g., l eukemia, central nervous system, renal) generally responded with GI(50 ) concentrations in the low-to-mid nanomolar range.