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Melatonin: a hormone, a tissue factor, an autocoid, a paracoid, and an antioxidant vitamin
Author(s) -
Tan DunXian,
Manchester Lucien C.,
Hardeland Rüdiger,
LopezBurillo Silvia,
Mayo Juan C.,
Sainz Rosa M.,
Reiter Russel J.
Publication year - 2003
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1034/j.1600-079x.2003.02111.x
Subject(s) - melatonin , antioxidant , hormone , biology , pineal gland , medicine , endocrinology , biochemistry
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.