Melatonin is a potent antioxidant. Antioxidative actions of melatonin include directly detoxifing a number of free radicals and non-radical products and indirectly stimulating the activity and gene expression of antioxidative and pro-oxidative enzymes. Melatonin can stimulate glutathione (GSH) synthesis, reduce electron leakage from the mitochondrial electron transport chain, limit cytokine production and inflammatory processes and act synergistically with other classic antioxidants. Furthermore, several metabolites that are formed when melatonin scavenges damaging reactants are themselves'scavengers suggesting that there is cascade of reactions that greatly increase the efficacy of melatonin in stymying oxidative mutilation. Recently, however, melatonin was identified in plants. In several Chinese medicinal herbs, melatonin levels are in excess of 1000 ng per gram dry mass,these high level-melatonin containing plants are traditionally used to treat diseases which presumably involve free radical damage.