| The phospholipid fatty composition of the marine sponges Haliclona sp., Axinyssa sp., Acanthella sp., Stylotella aurantium, Calyx podatypa and Callyspongia fallax was analyzed. The phospholipid fatty acid composition of the mollusk Siphonaria denticulata was also analyzed. The extraction of the total lipids from these organisms was followed by the separation of the different lipid classes by column chromatography. The fatty acids from the phospholipids were characterized by the GC-MS analysis of their respective methyl esters. Equivalent chain length (ECL) values of the gas chromatogram were used to identify possible ramifications in the fatty acyl chains. For the determination of the double bond positions dimethyldisulfide and pyrrolidide derivatives were prepared directly from the fatty acid methyl esters and analyzed by mass spectrometry.;From the marine organisms analyzed several different classes of fatty acids were characterized including branched, unsaturated, brominated, as well as 2-methoxylated fatty acids. Among these compounds we found several fatty acids that have not been previously reported from any natural source. In the Caribbean sponge Calyx podatypa two novel fatty acids were identified, namely the acids 11-methylpentadecanoic acid and 9,13 dimethyltetradecanoic acid, which were also synthesized for the first time in this work. In Callyspongia fallax six novel 2-methoxylated fatty acids were identified, namely the 2 methoxytetradecanoic acid, 2-methoxypentadecanoic acid, 2-methoxyoctadecanoic acid, 2-methoxy-6(Z)-tetradecenoic acid, 2-methoxy-6(Z)-pentadecenoic acid and 2 methoxy-13-methyl-6(Z)tetradecenoic acid.;In addition to the two novel fatty acids from C. podatypa, the 10,13-dimethyltetradecanoic acid was also isolated from this sponge and synthesized for the first time. The glyceryl ether of 10,13-dimethyltetradecan-1-ol, an intermediate in the total synthesis of this acid, was also synthesized in order to explore its potential antimicrobial activity.;Another novel fatty acid synthesized in this work is the 16-methyl-8(Z)-heptadecenoic acid, which was isolated from the marine bacterium Micrococcus sp . In all of the accomplished syntheses the key step to complete the carbon skeleton was the Wittig olefination, and these were completed in 17--62% overall yields. The synthetic fatty acids were used to corroborate the structures of the original samples. |
