Studies on the role of vitamin E in the oxidation of blood components by fatty hydroperoxides.

Studies are reported on the oxidation of vitamin E and changes in lipid and fatty acid composition of rat blood components incubated in vitro with hydroperoxides prepared from autoxidized methyl linoleate. Red blood cells, plasma, serum, and hemoglobin free stroma were incubated at 37 °C with suspensions of linoleate hydroperoxide in Tris buffer at pH 7.4. The RBC were destroyed and substances with excitation-fluorescent properties were produced. Phosphatidylethanolamine, vitamin E and unsaturated fatty acids were oxidized in the reaction. Among the reaction products were substances that gave a positive thiobarbituric acid value, tocoquinone, and an unidentified substance isolated in the nonsaponifiable fraction of the lipid extract of the hemolyzed red cells. The reaction of linoleate hydroperoxide with stroma was similar to that with red blood cells and the same products were observed. In contrast there was little reaction of linoleate hydroperoxide with vitamin E or lipids of the serum or plasma in the absence of red blood cells. The destruction of the red blood cells appeared to be closely related to the oxidation of vitamin E indicating that the strong antioxygenic action of vitamin E in vivo was due to its particular form or structural orientation in the red cell membrane.