New 24-isopropylcholesterol and 24-isopropenylcholesterol sulfate from the marine sponge Epipolasis species.

Two novel steroids, polasterol A (1) and polasterol B sulfate (2), along with two known compounds, 22(E),24-isopropylcholesta-5, 22-dien-3 beta-ol (3) and halistanol sulfate (4), have been isolated from the Japanese marine sponge Epipolasis sp. The structures of 1 and 2 were determined as 3 beta-hydroxy-24-isopropylcholesta-5, 22(E)-dien-7-one and 24xi-isopropenylcholesta-22(Z), 28(29)-diene-2 beta,3 alpha,6 alpha-triyl trisodium sulfate on the basis of spectroscopic investigations and a chemical conversion.