New acetylenic acids from the marine sponge Stelletta species.

Four new acetylenic acids were isolated from the marine sponge Stelletta sp. by bioactivity-guided fractionation. The planar structures were established on the basis of NMR and MS analysis. The stereochemistry was defined by combined use of CD spectroscopy and a chiral anisotropic reagent, phenylglycine methyl ester (PGME). The compounds were evaluated for cytotoxicity against a small panel of five human tumor cell lines and exhibited marginal to moderate cytotoxicity.