Comparison of the Protective Effects of Epigallocatechin Gallate and Epigallocatechin on Paraquat-Induced Oxidative Stress in Rats

The protective effects of (—)-epigallocatechin gallate (EGCg) and (—)-epigallocatechin (EGC) on paraquat-induced oxidative stress were compared in rats. Both EGCg and EGC effectively relieved decreases in food intake and body weight gain which were a result of administering the paraquat diet. The concentration of thiobarbituric acid-reactive substances (TBARS) in the liver of rats fed with the EGCg-added paraquat diet was lower than that of the EGC-added paraquat diet. The antioxidative enzyme activities in serum and liver, except for the catalase activity of the liver mitochondrial fraction, were not significantly different among the control, paraquat, paraquat+EGCg, and paraquat+EGC diet-fed rats. The catalase activity of the liver mitochondrial fraction was markedly decreased by feeding the paraquat diets and the decrease was strongly relieved by supplementing EGCg rather than EGC in the paraquat diet. On the other hand, decreases in the liver glutathione, cysteine and triacylglycerol concentrations that were caused by the paraquat diet had greater relief by supplementing EGCg rather than EGC in the paraquat diet. These results may suggest that the gallic acid moiety of the EGCg molecule plays an important role in demonstrating stronger protective effects for paraquat-induced oxidative stress.