Effect of melatonin, piperonyl butoxide, or cobalt chloride on l-cysteine-induced lipid peroxidation in homogenate from whole brain of mice

Abstract

Brain homogenates exposed to a low concentration of l-cysteine (0.05, 0.1, 0.5, 1.0, and 2.0 mM) were significantly increased in their concentration of malondialdehyde (MDA) + 4-hydroxyalkenals (4-HDA) as compared to control samples, in a concentration-dependent manner. The increased lipid peroxidation by l-cysteine was attenuated or completely abolished by co-incubation with melatonin (2 mM), a potent free radical scavenger, piperonyl butoxide (1 mM), an inhibitor of mixed function oxidase, or cobalt chloride (0.01, 0.02 or 0.05 mM), another inhibitor of mixed function oxidase, but not allopurinol (0.1 mM), an inhibitor of xanthine oxidase. In addition, when a brain homogenate heated at 85 °C for 1 min was incubated with or without l-cysteine at 37 °C for 20 min, MDA + 4-HDA levels in the homogenate was not changed between l-cysteine and control. These results suggest that l-cysteineinduced lipid peroxidation may be involved in the enzymatic mixed function oxidation systems in brain.