Hydroperoxides of erythrocyte phospholipid molecular species formed by lipoxygenase correlate with alpha-tocopherol levels.

The hydroperoxides corresponding to the main molecular species of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were determined after lipoxygenase treatment of erythrocyte membranes from healthy children. This work was a preliminary study prior to applying this analytical procedure to erythrocyte membranes from children with diseases associated with vitamin E deficiency. The total molecular species corresponding to 20:4 and 22:6 associated with 16:0 and 18:0 were significantly higher in PE (26.94 +/- 4.70 nmol/mg protein) than in PC (20.14 +/- 6.70 nmol/mg protein); these concentrations represented 63% of the total molecular species in PE and 22% in PC. However, the concentrations of hydroperoxides produced from these polyunsaturated fatty acid molecular species were in the same order of magnitude in PC (3.98 +/- 1.56 nmol/mg protein) and in PE (3.61 +/- 1.63 nmol/mg protein). In contrast, the molecular species concentrations containing two double bonds, such as 16:0/18:2 and 18:0/18:2 and their corresponding hydroperoxides, were clearly more elevated in PC than in PE. There was a positive relationship between the concentrations of alpha-tocopherol and each hydroperoxide of PC and PE, and this association was particularly strong in PE (P < or = 0.0001). These results suggest that alpha-tocopherol exerts a stabilizing effect toward hydroperoxides, limiting their further degradation into peroxyl radicals. The protective effect of alpha-tocopherol could be more effective in PE because more polyunsaturated fatty acids were present.