HYDROPEROXIDES OF ERYTHROCYTE PHOSPHOLIPID MOLECULAR-SPECIES FORMED BY LIPOXYGENASE CORRELATE WITH ALPHA-TOCOPHEROL LEVELS

The hydroperoxides corresponding to the main molecular species of phos phatidylcholine (PC) and phosphatidylethanolamine (PE) were determined after lipoxygenase treatment of erythrocyte membranes from healthy ch ildren. This work was a preliminary study prior to applying this analy tical procedure to erythrocyte membranes from children with diseases a ssociated with vitamin E deficiency. The total molecular species corre sponding to 20:4 and 22:6 associated with 16:0 and 18:0 were significa ntly higher in PE (26.94 +/- 4.70 nmol/mg protein) than in PC (20.74 /- 6.70 nmol/mg protein); these concentrations represented 63% of the total molecular species in PE and 22% in PC. However, the concentratio ns of hydroperoxides produced from these polyunsaturated fatty acid mo lecular species were in the same order of magnitude in PC (3.98 +/- 1. 56 nmol/mg protein) and in PE (3.61 +/- 7.63 nmol/mg protein). In cont rast, the molecular species concentrations containing two double bonds , such as 16:0/18:2 and 18:0/18:2 and their corresponding hydroperoxid es, were clearly more elevated in PC than in PE. There was a positive relationship between the concentrations of alpha-tocopherol and each h ydroperoxide of PC and PE, and this association was particularly stron g in PE (P less than or equal to 0.0001). These results suggest that a lpha-tocopherol exerts a stabilizing effect toward hydroperoxides, lim iting 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.