Steroids from a Far-Eastern Glass Sponge Aulosaccus sp.

This report concerns the identification of steroid constituents of a Far-Eastern glass sponge Aulosaccus sp. (the Sea of Okhotsk), belonging to one of the least chemically investigated group of sponges. Steroid mixtures, isolated from the extract of Aulosaccus sp., were fractionated by high-performance liquid chromatography on normal-phase and/or reversed-phase columns, and the obtained fractions were analyzed by nuclear magnetic resonance spectroscopy and gas chromatography-mass spectrometry. In result, 64 compounds, including 32 3-keto derivatives of sterols with saturated, Delta(7)-, Delta(8(14))-, Delta(4)-, and Delta(4,6)-tetracyclic systems and 32 sterols (stanols, 4 alpha-methyl-stanols, Delta(5) -, Delta(7)-, 4 alpha-methyl-Delta(8(14))-sterols), were identified. Most of these steroids were not found in glass sponges earlier. The structures of 2 new steroids, 24-propyl-5 alpha-cholest-24(28)Z-en-3-one and 24-nor-cholest-4-en-3-one, were elucidated. Sterol esters were not found. 3-Keto derivatives of stanols were major components in the steroids of Aulosaccus sp. It is probable that association of Aulosaccus sp. with bacteria, capable of oxidizing sterols, led to the transformation of a significant part of sponge sterols into their 3-keto derivatives.