title: Vitamin E consumption induced by oxidative stress in red blood cells is enhanced by melatonin and reduced by N-acetylserotonin.
abstract: The effect of melatonin and its precursor N-acetylserotonin was studied in a model of lipid peroxidation induced in human red blood cells by incubation with cumene hydroperoxide (CHP) and H2O2. The oxidative stress was expressed as vitamin E consumption in the presence of melatonin or N-acetylserotonin (concentration ranging from 0.3 to 400 microM): incubation with melatonin not only lacked any protective effect but it induced a dose-dependent extra vitamin E consumption with both CHP and H2O2. On the contrary, N-acetylserotonin showed a strong antioxidant effect at concentrations between 100 and 400 microM. The hydrogen-donating capacity of melatonin and N-acetylserotonin was also evaluated from the decay of the ESR signal of galvinoxyl radical used as hydrogen abstractor. Lack of hydrogen-donating capacity was observed with melatonin, whereas N-acetylserotonin showed a significant hydrogendonating capacity although inferior to vitamin E, thus suggesting that N-acetylserotonin acts by the classical antioxidant mechanism of hydrogen donation. The measurement of the oxidation potential and the specific molecular structure suggest that the vitamin E consumption effect observed with melatonin could be due to the interactions of its radical cation or derivatives on vitamin E.
authors.affiliation: Department of Physiology and Biochemistry, University of Pisa, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Barsacchi
authors.forename: C
authors.initials: C
authors.lastname: Kusmic
authors.forename: E
authors.initials: E
authors.lastname: Damiani
authors.forename: P
authors.initials: P
authors.lastname: Carloni
authors.forename: L
authors.initials: L
authors.lastname: Greci
authors.forename: L
authors.initials: L
authors.lastname: Donato
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D001555:Benzene Derivatives / Q000494:pharmacology; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism*; D005609:Free Radicals / Q000097:blood; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D066298:In Vitro Techniques; D015227:Lipid Peroxidation / Q000187:drug effects; D008550:Melatonin / Q000494:pharmacology*; D008954:Models, Biological; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000187:drug effects; D012701:Serotonin / Q000031:analogs & derivatives* / Q000494:pharmacology; D014810:Vitamin E / Q000097:blood*
chemical_list: D000975:Antioxidants; D001555:Benzene Derivatives; D005609:Free Radicals; D016877:Oxidants; D014810:Vitamin E; D012701:Serotonin; D006861:Hydrogen Peroxide; D008550:Melatonin; C006389:N-acetylserotonin; C007164:cumene hydroperoxide