title: Scavenging effect of melatonin on hydroxyl radicals generated by alloxan.
abstract: Alloxan can act as a generator of reactive oxygen species (ROS) as long as sufficient suitable reducing agents (e.g. reduced glutathione) and oxygen are available. Using electron spin resonance-spectroscopy and the oxygen-centered spin trap DEPMPO, we demonstrate that hydroxyl radicals (OH.) are formed in vitro by alloxan in the presence of glutathione (GSH) and chelated divalent iron. Furthermore, peroxidation of polyunsaturated fatty acids from phosphatidylcholine-containing liposomes with concomitant formation of malondialdehyde (MDA) was used as a further indicator for a preceding OH. formation. Melatonin, the main secretory product of the pineal gland, is an effective scavenger of OH.. The 50%-inhibitor concentration (IC50-value) for melatonin to scavenge OH. generated from the alloxan/GSH-reaction in the presence of ferrous ions was 23 micromol/L. In contrast to the ability to effectively scavenge OH., the potential of melatonin to prevent lipid peroxidation is considerably less pronounced.
authors.affiliation: Institutes of Pathophysiology Analytic, Martin Luther University, Halle-Wittenberg, Germany.
authors.forename: H J
authors.initials: HJ
authors.lastname: Brömme
authors.forename: W
authors.initials: W
authors.lastname: Mörke
authors.forename: D
authors.initials: D
authors.lastname: Peschke
authors.forename: H
authors.initials: H
authors.lastname: Ebelt
authors.forename: D
authors.initials: D
authors.lastname: Peschke
mesh_terms: D000496:Alloxan / Q000494:pharmacology*; D004578:Electron Spin Resonance Spectroscopy; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D016166:Free Radical Scavengers / Q000494:pharmacology*; D005978:Glutathione / Q000494:pharmacology; D017665:Hydroxyl Radical / Q000378:metabolism*; D066298:In Vitro Techniques; D015227:Lipid Peroxidation / Q000187:drug effects; D008081:Liposomes; D008315:Malondialdehyde / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D005231:Fatty Acids, Unsaturated; D016166:Free Radical Scavengers; D008081:Liposomes; D017382:Reactive Oxygen Species; D017665:Hydroxyl Radical; D008315:Malondialdehyde; D000496:Alloxan; D005978:Glutathione; D008550:Melatonin