Melatonin and tryptophan derivatives as free radical scavengers and antioxidants

R. J. Reiter, D. X. Tan, J. Cabrera, D. D'Arpa

Research output: Contribution to journalArticlepeer-review

106 Scopus citations


Several tryptophan derivatives function as free radical scavengers and antioxidants. The molecule that has been most widely investigated in this regard is N-acetyl-5-methoxytryptamine (melatonin): however, pinoline (6-methoxy-1,2,3,4-tetrahydro-β-carboline) and N-acetylserotonin also possess free radical scavenging activity. Experimental studies have shown that melatonin directly scavenges the hydroxy radical, peroxyl radical, peroxynitrite anion, and singlet oxygen. Furthermore, this tryptophan derivative stimulates a number of antioxidative enzymes and stabilizes cell membranes: this latter action helps membranes to resist free radical damage. While the antioxidative actions of most molecules are limited by their specific intracellular distribution, e.g., vitamin E in lipid-rich membranes, melatonin's antioxidative actions include the protection of lipids in the cell membrane, proteins in the cytosol, and DNA in the nucleus. Furthermore, melatonin crosses all morphophysiological barriers and enters equally well all cells in the organism.

Original languageEnglish (US)
Pages (from-to)379-387
Number of pages9
JournalAdvances in experimental medicine and biology
StatePublished - Dec 1 2000

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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