Biochemical and Molecular Actions of Nutrients Vitamin E Supplementation Decreases Basal Levels of F 2-Isoprostanes and Prostaglandin F 2 a in Rats 1

Lipid peroxidation is thought to be an important factor in the pathophysiology of a number of diseases and in the process of aging. We investigated the effects of supplementation with vitamin E on lipid peroxidation in rats. Both free radical-induced nonenzymaticand cyclooxygenase-catalyzed enzymatic lipid peroxidation were investigated by measuring the levels of F2-isoprostanes (8-iso-PGF2a) and PGF2a-metabolite (15-K-DH-PGF2a), respectively, in blood, urine and liver. Samples were collected from control rats (n 5 6) and from rats supplemented with vitamin E in the diet for 3 wk (n 5 8, 20 g/kg diet of DL-a-tocopherol hydrogen succinate). Plasma a-tocopherol concentration and antioxidative capacity were greater in the vitamin Esupplemented rats than in the control rats (17.9 6 1.7 vs. 50.4 6 10.4 mmol/L, P , 0.001 and 181 6 6 vs. 275 6 27 mmol/L trolox equivalents, P , 0.001). Urine 8-iso-PGF2a tended to be lower in the vitamin Esupplemented rats (0.72 6 0.40 vs. 0.34 6 0.19 nmol/mmol creatinine, P 5 0.056). Urine 15-K-DH-PGF2a was lower due to vitamin E supplementation (0.97 6 0.38 vs. 0.56 6 0.21 nmol/mmol creatinine, P , 0.05), as was liver-free 8-iso-PGF2a concentration (0.47 6 0.11 vs. 0.18 6 0.04 nmol/g, P , 0.001). Supplementation with vitamin E did not affect plasma 8-iso-PGF2a or 15-K-DH-PGF2a concentrations, liver total 8-iso-PGF2a or plasma malondialdehyde levels. Thus, vitamin E supplementation reduced urine basal levels of biomarkers of both nonenzymatic and enzymatic lipid peroxidation. In liver, vitamin E reduced the basal level of free 8-iso-PGF2a but not total 8-iso-PGF2a. J. Nutr. 130: 10 –14, 2000.