Melatonin: A hormone, a tissue factor, an autocoid, a paracoid, and an antioxidant vitamin

Dun Xian Tan, Lucien C. Manchester, Rüdiger Hardeland, Silvia Lopez-Burillo, Juan C. Mayo, Rosa M. Sainz, Russel J. Reiter

Research output: Contribution to journalArticlepeer-review

483 Scopus citations


Melatonin, a derivative of an essential amino acid, tryptophan, was first identified in bovine pineal tissue and subsequently it has been portrayed exclusively as a hormone. Recently accumulated evidence has challenged this concept. Melatonin is present in the earliest life forms and is found in all organisms including bacteria, algae, fungi, plants, insects, and vertebrates including humans. Several characteristics of melatonin distinguish it from a classic hormone such as its direct, non-receptor-mediated free radical scavenging activity. As melatonin is also ingested in foodstuffs such as vegetables, fruits, rice, wheat and herbal medicines, from the nutritional point of view, melatonin can also be classified as a vitamin. It seems likely that melatonin initially evolved as an antioxidant, becoming a vitamin in the food chain, and in multicellular organisms, where it is produced, it has acquired autocoid, paracoid and hormonal properties.

Original languageEnglish (US)
Pages (from-to)75-78
Number of pages4
JournalJournal of pineal research
Issue number1
StatePublished - Jan 2003


  • Antioxidant
  • Diet
  • Free radical
  • Hormone melatonin
  • Plant
  • Vitamin

ASJC Scopus subject areas

  • Endocrinology


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