Inhibitory Effect of Capsaicin against Carcinogen-induced Oxidative Damage in Rats

Abstract

Capsaicin (trans-8-methyl-N-vanillyl-6-nonenamide), a major pungent component of hot pepper, is known to exert antioxidative properties. In this study, we investigated the protective effects of capsaicin against chemical carcinogen-induced oxidative damage in rats. Male Sprague Dawley rats weighting 230～250 g were treated with chemical carcinogens such as 2-nitropropane (2NP) or n-methyl-N'-nitro-N-nitrosoguanidine (MNNG) after (or before) the administration of capsaicin at doses of 0.5, 1, 5 mg/kg. The level of lipid peroxidation in rat liver was estimated by measuring the amounts of thiobarbituric acid reactive substances. The degree of oxidative DNA damage was evaluated by measuring a DNA adduct, 8-hydroxydeoxyguanosine (8-OHdG), in urine. Antioxidative activities of capsaicin, its metabolites in vitro were determined by the measurement of DPPH (1,1-diphenyl-2-picrylhydrazyl), a radical quencher. Significant inhibition of 2-NP induced lipid peroxidation was observed in the liver of the rat when treated with capsaicin. MNNG-induced urinary excretion of 8-OHdG was decreased by capsaicin treatment. Capsaicin, its metabolites inhibited not only the formation of free radicals, but also lipid peroxidation in vitro. Our results show that capsaicin may function as a free radical scavenger against chemical carcinogen-induced oxidative cellular damage in vivo. The observed antioxidative activities of capsaicin may play an important role in the process of chemoprevention.