Oxidized Positions of Fatty Acyl Moieties of Phosphatidyl-ethanolamine in Liposome Autoxidation

Liposomes of soybean and egg yolk phosphatidylethanolamine (PE) were oxidized in the presence of copper. Fatty acyl moieties with hydroxy and hydroperoxy groups attached were converted to methyl esters. The methyl esters were separated in TLC and then separated on silicic acid thin layer plates containing AgNO₃. After GLC purification, hydrogenated and trimethylsily- lated samples were analyzed for positional isomers in MS. Fatty acids, 18:2 and 18:3 in soybean PE and 18:2, 20:4, and 22:6 in egg yolk PE were examined. A singlet oxygen mechanism was presumably involved in part, but to explain the whole isomer pattern, some yet unexplained mechanism appears to be involved.