Isolation and characterization of antiplasmodial constituents from the marine sponge Coscinoderma sp.

Abstract

Six known compounds, namely two halisulfates 1 and 2 and four epidioxy sterols 3-6, were isolated from the marine sponge Coscinoderma sp. The structures of these compounds were confirmed by nuclear magnetic resonance (H-1 and C-13 NMR) spectroscopy, and their antiplasmodial activities were determined against the chloroquine-resistant Dd2 strain of Plasmodium falciparum. The epidioxy steroids 3-6 all showed moderate to weak antiplasmodial activity, with IC50 values of 2.7 mu M for (24S)-5 alpha,8 alpha-epidioxy-24-methylcholesta-6-en-3 beta-ol (3), 11.6 mu M for 5 alpha,8 alpha-epidioxycholesta-6,24(28)-dien-3 beta-o1 (4), 2.33 mu M for 5 alpha,8 alpha-epidioxy-24-methylcholesta-6,9(11)24(28)-trien-3 beta-ol (5), and between 12 and 24 mu M for 5 alpha,8 alpha-epidioxycholesta-6-en-3 beta-ol (6). In contrast, halisulfate 2 (1) was inactive, and halisulfate 1 (2) had an of IC50 value of about 24 mu M.