2 NEW STEROID DERIVATIVES FROM THE SOFT CORAL SINULARIA-GIBBEROSA OF THE ANDAMAN-AND-NICOBAR ISLANDS

Chemical examination of the ethyl acetate extract of the soft coral Si nularia gibberosa, collected from the Diglipur Island of the group of A & N Islands, furnishes eight pure compounds (1-8) besides a mixture of monohydroxysterols. Two of these are new compounds, one a steroid g lycoside, (24S)-24-methylcholest-5-ene-3 beta, 16 beta-diol-3-O-alpha- L-fucopyranoside (1) and the second a 5 alpha, 8 alpha-epidioxysterol with 22, 23-cyclopropane side chain, 5 alpha, 8 alpha-epidioxy-23, 24- didemethylgorgost-6-en-3 beta-ol (2). While two of the remaining six, 24-methylenecholest-5-ene-3 beta, 16 beta-diol-3-O-alpha-L-fucopyranos ide (7) and 24-methylenecholest-5-ene-3 beta, 7 beta, 16 beta-triol-3- O-alpha-L-fucopyranoside (8) are steroid glycosides reported earlier f rom the same species, four, 3,4-epoxycembrene (3), (24S)-24-methylchol est-5-en-3 beta-ol (4), (24S)-24-methylcholestane-3 beta, 5 alpha, 6 b eta, 25-tetrol-25-monoacetate (5) and (24S)-24-methylcholestane-3 beta , 5 alpha, 6 beta, 25-tetrol (6) are being reported for the first time from this soft coral. The structures have been derived by a study of their spectral (UV, IR, H-1 and C-13 NMR and mass) data.