1-O-alk-1′-enyl-2-acyl-glycerophosphoethanolamine content and molecular species composition in fish brain

Ethanolamine glycerophospholipids from the brains of both trout and cod comprised 36–38% of 1-O-alk-1′-enyl-2-acyl-glycerophosphoethanolamine (GPE) determined using two methods. In 1-O-alk-1′-enyl-2-acyl-GPE from trout brain, the main molecular species were 18∶1a/18∶1, 18∶0a/18∶1 and 16∶0a/18∶1, which totalled 63.3%, while polyunsaturated fatty acid (PUFA) containing species totalled only 18.2%. 1-O-Alk-1′-enyl-2-acyl-GPE from cod brain was much more unsaturated with PUFA containing species totalling 52.6%, of which 18∶0a/20∶5n−3, 18∶1a/20∶5n−3 and 18∶1a/22∶6n−3 were predominant. In cod 18∶1a/18∶1, 18∶0a/18∶1 and 16∶0a/18∶1 were the only other species present at over 5% each, totalling 31.8%. In both cod and trout, small amounts of species containing 22∶4n−6 were found. The results of this and earlier studies indicate that there is considerable specificity of composition at the level of molecular species between different lipid classes and subclasses. Molecular species of 1-O-alk-1′-enyl-2-acyl-GPE are abbreviated as follows:e.g., 16∶0a/18∶1 GPE is 1-O-hexadec-1′-enyl-2-oleoyl-sn-glycero-3-phosphoethanolamine. The corresponding diacyl species, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine, is abbreviated as 16∶0/18∶1.