engleski

Novel Di-, Tri-, and Tetraenoic Fatty Acids with bis-Methylene-Interrupted Double-Bond Systems from the Sponge Haliclona cinerea

Unusual fatty acids, with up to 34 carbon atoms and containing one or two bis-methylene-interrupted double- bond 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.

Haliclona cinerea; Porifera; Lipid composition; unsaturated fatty acids

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