Melatonin as an antioxidant: Biochemical mechanisms and pathophysiological implications in humans

Russel J. Reiter, Dun Xian Tan, Juan C. Mayo, Rosa M. Sainz, Josefa Leon, Zbigniew Czarnocki

Research output: Contribution to journalReview articlepeer-review

487 Scopus citations


This brief resume enumerates the multiple actions of melatonin as an antioxidant. This indoleamine is produced in the vertebrate pineal gland, the retina and possibly some other organs. Additionally, however, it is found in invertebrates, bacteria, unicellular organisms as well as in plants, all of which do not have a pineal gland. Melatonin's functions as an antioxidant include: a), direct free radical scavenging, b), stimulation of antioxidative enzymes, c), increasing the efficiency of mitochondrial oxidative phosphorylation and reducing electron leakage (thereby lowering free radical generation), and 3), augmenting the efficiency of other antioxidants. There may be other functions of melatonin, yet undiscovered, which enhance its ability to protect against molecular damage by oxygen and nitrogen-based toxic reactants. Numerous in vitro and in vivo studies have documented the ability of both physiological and pharmacological concentrations to melatonin to protect against free radical destruction. Furthermore, clinical tests utilizing melatonin have proven highly successful; because of the positive outcomes of these studies, melatonin's use in disease states and processes where free radical damage is involved should be increased.

Original languageEnglish (US)
Pages (from-to)1129-1146
Number of pages18
JournalActa Biochimica Polonica
Issue number4
StatePublished - 2003


  • Antioxidant
  • Antioxidant enzymes
  • Free radicals
  • Melatonin
  • Neurodegeneration
  • Respiratory distress
  • Sepsis

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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