Sterols and related metabolites from five species of sponges

Free sterol fractions were isolated from the marine sponges Phyllospongia madagascarensis, Scalarispongia sp., Oceanapia sp., Monanchora clathrata and studied by GLC, GLC–MS, and spectroscopy NMR. P. madagascarensis and Scalarispongia sp. contained common Δ5-sterols; cholesterol was shown to be a main sterol of both the sponges. Oceanapia sp. contained stanols and minor Δ5-sterols with 24R-24,25-methylene-5α-cholestan-3β-ol as a main constituent. Many free sterols from M. clathrata were Δ7-series compounds, and latosterol was a main sterol. Δ4-3-Ketosteroids and Δ5-sterol esters were found in the Antarctic sponge Haliclona sp., but free sterols were practically absent except for trace amount of cholesterol. A chemotaxonomic application of sterols in relation to the genera Phyllospongia, Oceanapia and the family Crambeidae is provided. The known cases of the absence of sterols in sponges and probable reasons of the phenomenon are discussed.