New isomalabaricane triterpenes from the marine sponge Stelletta globostellata that induce morphological changes in rat fibroblasts.

ABSTRACT

Three new isomalabaricane triterpenes, 29-hydroxystelliferin D (2), 3-epi-29-hydroxystelliferin E (3), and 3-epi-29-hydroxystelliferin A (4), were isolated from the marine sponge Stelletta globostellata. Their structures, including absolute stereochemistry, were determined on the basis of spectral data and chemical methods. Rat fibroblasts treated with 0.2 microM of 2-4 exhibited unusual morphological characteristics, followed by death in 5 days.