Assay of hepatic levels of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA) and catalase (CAT)

Liver tissue samples were homogenized in nine volumes of ice-cold 50 mM phosphate buffer (pH 7.4) and centrifuged at 3,200 × g for 20 min at 4°C. Supernatants were used to determine SOD, GSH-Px, MDA, CAT and total protein concentrations by using commercially available diagnostic kits (SOD assay kit; cat no. A001-3; GSH-PX assay kit; cat no. A005; cat no. MDA assay kit; cat no. A003-1; CAT assay kit; cat no. A007-1; total protein assay kit; cat no. A045-3; Nanjing Jiancheng Bio Co., Ltd.). The levels of MDA, GSH-Px, SOD and CAT were normalized to the content of total protein.