*4.7. Determinations of GSH, GSH Peroxidase Activity, and Lipid Peroxidation*

Plasma and liver homogenate were used to determine the reduced (GSH) or oxidized glutathione (GSSG) content by the HPLC/MS method as reported previously [27]. Glutathione peroxidase activity was determined spectrophotometrically according to the method of Mohandas et al. [28]. Lipid peroxidation, as measured by thiobarbituric acid reactive substances (TBARS), in plasma and tissues were assessed by the modified method of Mihara and Uchiyama [29]. 1,1,3,3-Tetramethoxypropane (Sigma, USA) was used to determine the concentrations of TBARS in the samples. Fluorescence was measured at excitation and emission wavelengths of 515 nm and 553 nm, respectively.
