New cytotoxic isomalabaricane triterpenes from the sponge Jaspis species

Three new isomalabaricane triterpenes, 29-hydroxystelliferin E (1), 29-hydroxystelliferin A (2), and stelliferin G (3), together with the known triterpene 3-epi-29-tiydroxystelliferin E (4), were isolated from the organic extract of the sponge Jaspis sp. collected in the South Pacific. All the compounds isolated showed antiproliferative activity against melanoma cells (MALME-3M).