| Abstrakt: |
Unusual fatty acids, with up to 34 carbon atoms and containing one or two bis-methylene-interrupted doublebond systems, have been identified in the sponge Haliclona cinerea from the Black Sea. These include the dienes—5,9- 16:2, 7,11-18:2, 9,13-20:2, 13,17-24:2, 15,19-26:2, 17,21- 28:2, 19,23-30:2 and 21,25-32:2; trienes—5,9,23-30:3, 5,9,24- 31:3, 5,9,25-32:3, and 5,9,27-34:3; and the tetraenes— 5,9,19,23-30:4, 5,9,21,25-32:4, and 5,9,23,27-34:4. In addition, 5,9,13-eicosatrienoic acid was present. Many of these do not appear to have been described before, and only 5,9-16:2 and 5,9,23-30:3 are found often in sponges. They were identified by using silver-ion high-performance liquid chromatography to simplify the complex mixture of fatty acids for subsequent analysis by gas chromatography–mass spectrometry as picolinyl ester derivatives. Deuteration with Wilkinson’s catalyst in homogeneous solution confirmed the structures. We speculate that the di- and tetraenoic fatty acids arise by chain elongation of 5,9-hexadecadienoic acid, also a major component of the lipids, followed by further insertion of double bonds in the 5 and 9 positions. The trienes may be formed from 9-hexadecenoic acid by similar mechanisms. [ABSTRACT FROM AUTHOR] |
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