To measure activities of SOD, catalase (CAT) and glutathione peroxidase (GSH-Px), antioxidant enzyme source of liver tissue was prepared. In brief, 1 g of liver tissue was mixed with 10 times volume of 50 mM phosphate buffer (pH 7.4) and homogenized using a glass teflon homogenizer. After the mixture was centrifuged at 3,000 rpm at 4℃ for 10 minutes, the supernatant was used for measurement of CAT and GSH-Px activities. The supernatant was further centrifuged at 13,000 rpm for 20 minutes and the remaining supernatant was used for measurement of SOD activity. SOD activity was assayed according to the method developed by Marklund and Marklund (1974).