Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
The steroidal components of a Red Sea sponge, Biemna fortis, were fractionated through reversed phase HPLC. and analyzed by a combination of physical methods, including high resolution GC./MS. and 360 MHz 1H-NMR. The sponge contains five conventional Δ5-sterols, 1a-c, 1e, 1g, which comprise about 25% of the mixture and 2,5% of gorgosterol (1h), a sterol never found before in Porifera. Three Δ5,7,22-sterols were also present as major components in the mixture (∼70%): cholesta-5,7,22-trien-3β-ol (2a), ergosta-5,7,22-trien-3β-ol (2c) and (24R)-ethylcholesta-5,7,22-trien-3β-ol (2e) whereas two new tetra-unsaturated sterols were identified in minor amounts (2%): ergosta-5,7,9(11),22-tetraen-3β-ol (3c) and 24ξ-ethylcholesta-5,7,9 (11), 22-tetraen-3β-ol (3e or 3f). NMR. spectroscopy made possible the assignment of a 24R configuration for all the C(24) substituted sterols isolated in sufficient amount from the mixture. The possible symbiotic, dietary or biosynthetic origins of these sterols are discussed.
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