Chemoprotection against N-methyl-n'-nitro-N-nitrosoguanidine-induced oxidative stress by s-allylcysteine, a garlic constituent, in wistar rats.

S-allylcysteine (SAC), a water-soluble garlic constituent, was tested for its protective effect against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced oxidative stress in male Wistar rats. Three different concentrations of SAC (100, 200, and 400 mg/kg (-) 1 body weight) were administered intragastrically for 5 consecutive days, followed by intragastric intubation of MNNG 1(1/2) h after the final administration. Measurement of lipid peroxidation, reduced glutathione (GSH), glutathione peroxidase (GPx), and glutathione S-transferase (GST) in the stomach, liver, and erythrocytes was used to monitor the chemoprotective effects of SAC. Enhanced lipid peroxidation in MNNG-treated rats was accompanied by a significant decrease in glutathione and in the activities of GPx and GST. Administration of SAC at the concentration of 200 and 400 mg/kg (-) 1 body weight significantly reduced the concentration of lipid peroxides and enhanced the levels of GSH-dependent antioxidants and detoxifying enzymes. Our findings suggest that SAC exerts chemoprotective effects, even at a concentration of 200 mg/kg (-) 1 body weight, against MNNG-induced oxidative stress by decreasing lipid peroxidation and enhancing the antioxidant status.