) Some biochemical properties of melatonin and the characterization of a relevant metabolite arising from its interaction with H2O2.

Melatonin is an efficient protector against H2O2-induced lipid peroxidation and acts in a concentrationdependent manner. H2O2 rather a water stable molecule which is able to cross the cell membrane much better than some important free radicals such as superoxide anion, and consequently its local production can lead to significant spread by diffusion. In this paper we report data regarding some biochemical properties of melatonin as well as the chemical characterization of the major product formed from the interaction between melatonin and H2O2 (N1-acetylN2-formyl-5-metoxykynuramine) that are consistent with previous data reported by other authors. The effect of melatonin on catalase, glutathion peroxidase and superoxide dismutase in in vitro and in vivo experiments is also reported.