title: Melatonin: Free Radicals and Metabolites Resulting by Emission and Consumption of Solvated Electrons (eaq-): Reaction Mechanisms.
abstract: OBJECTIVE
  Melatonin not only regulates circadian rhythm, but also induces apoptosis in tumor cells. Hence, elucidation of the basic reaction mechanisms of melatonin and its metabolites is a matter of interest.
  
  
  METHODS
  Melatonin dissolved in a mixture of water/ethanol=40/60 form associates (unstable complexes). For simulation of biological processes, melatonin was excited by UV light into the singlet state.
  
  
  RESULTS
  By using monochromatic UV light (λ=254 nm) melatonin ejects solvated electrons (eaq (-)), a part of which is scavenged by melatonin in ground state contained in the associates. Consequently, with increase of melatonin concentration a decrease of the determined quantum yield of emitted eaq (-), Q(eaq (-)), is obtained. The complex molecular structure of melatonin contains functional groups which can emit eaq (-), as well such consuming eaq (-). As a succession of these processes various types of metabolites are generated, as well as degradation products, with lower molecular weight, are formed.
  
  
  CONCLUSIONS
  Not melatonin per se, but the ejected eaq (-) and thereby resulting various metabolites are responsible for different biological properties of melatonin.
authors.affiliation: Section of Radiation Biology, Department of Nutritional Sciences, Faculty of Life Science, University of Vienna, Vienna, Austria.
authors.forename: Herbert
authors.initials: H
authors.lastname: Kneidinger
authors.affiliation: Clinical Department of Laboratory Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Goran
authors.initials: G
authors.lastname: Mitulovic
authors.affiliation: Section of Radiation Biology, Department of Nutritional Sciences, Faculty of Life Science, University of Vienna, Vienna, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Hartmann
authors.affiliation: Section of Radiation Biology, Department of Nutritional Sciences, Faculty of Life Science, University of Vienna, Vienna, Austria.
authors.forename: Ruth Maria
authors.initials: RM
authors.lastname: Quint
authors.affiliation: Section of Radiation Biology, Department of Nutritional Sciences, Faculty of Life Science, University of Vienna, Vienna, Austria nikola.getoff@univie.ac.at.
authors.forename: Nikola
authors.initials: N
authors.lastname: Getoff
mesh_terms: D000465:Algorithms; D000975:Antioxidants / Q000737:chemistry*; D004583:Electrons; D005609:Free Radicals / Q000737:chemistry; D008550:Melatonin / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure
chemical_list: D000975:Antioxidants; D005609:Free Radicals; D008550:Melatonin
keywords: Melatonin; free radicals; metabolites; solvated electrons