Alterations in lipid peroxides in rat liver by dietary n-3 fatty acids: modulation of antioxidant enzymes by curcumin, eugenol, and vitamin E

Abstract

Male Wistar rats fed a diet containing 10 wt% coconut oil, 10 wt% groundnut oil, or 10 wt% codliver oil for 10 weeks showed significant differences in lipid peroxides, mixed function oxidases, and antioxidant enzymes in liver homogenates. Rats fed codliver oil diets contained 136% and 80% higher levels of lipid peroxides, 38% and 28% higher activities of NADPH cytochrome C reductase, 42% and 30% higher levels of cytochrome P 450, and 41% and 30% higher levels of cytochrome b 5 compared with those observed in rats fed the other two diets. However, superoxide dismutase activity was reduced by 38%, catalase by 47%, glutathione peroxidase by 22%, and glutathione transferase activity by 32% in rats fed codliver oil as compared with those fed coconut oil diets. Vitamin E levels were lowered by 72% in animals fed codliver oil diets as compared with those on coconut oil diets. Ascorbic acid and glutathione levels were not changed by dietary lipids. The dietary antioxidants, curcumin (1 wt%), eugenol (0.17 wt%), or vitamin E (200 mg/kg diet) significantly enhanced ( P < 0.05) the activities of antioxidant enzymes; viz, superoxide dismutase, catalase, glutathione peroxidase, and glutathione transferase and lowered lipid peroxides in liver of animals fed coconut oil, groundnut oil, or codliver oil. Dietary vitamin E (200 mg/kg diet) enhanced hepatic stores of vitamin E while curcumin and eugenol had no appreciable influence on hepatic vitamin E levels. These antioxidants did not influence the levels of ascorbic acid and glutathione in liver homogenates. These studies indicate that dietary lipids and antioxidants modulate lipid peroxidation in rat liver by influencing antioxidant defense systems. (J. Nutr. Biochem. 5:181–188, 1994.)