The sterols of the sponge Petrosia spheroida collected in the Indian Ocean,
were isolated by liquid chromatography and reverse-phase HPLC. Sterols wer
e characterized by GC, GC-MS and in some cases by H-1- acid C-13-NMR. P. sp
heroida contained seven Delta(5)-unsaturated steroids with various C-8-C-10
side chains including petrosterol and 23,24-dihydrocalysterol, two cyclopr
opane-containing sterols. Chemotaxonomic considerations about the genus Pet
rosia are discussed. (C) 1998 Elsevier Science Inc. All rights reserved.