ABSTRACT
Oxidative stress is thought to be associated with the toxicity of numerous chemicals, with the pathogenesis of many disease processes in several different organ systems, and with diseases of aging. To protect against the deleterious effects of oxyradicals and to prevent lipid peroxidation processes, both nonenzymatic and enzymatic
antioxidant defense systems have evolved. Nonenzymatic cellular defenses include low molecular weight compounds such as Vitamins A and E, ascorbate, urate, and reduced glutathione (GSH). A second line of defense includes enzymes such as catalase, superoxide dismutase, and the GSH-dependent enzymatic system, where the key protecting enzymes are glutathione peroxidase (GPx) and the glutathione Stransferases (GSTs).
