Melatonin: a hormone, a tissue factor, an autocoid, a paracoid, and an antioxidant vitamin
Article first published online: 17 DEC 2002
Journal of Pineal Research
Volume 34, Issue 1, pages 75–78, January 2003
How to Cite
Tan, D.-X., Manchester, L. C., Hardeland, R., Lopez-Burillo, S., Mayo, J. C., Sainz, R. M. and Reiter, R. J. (2003), Melatonin: a hormone, a tissue factor, an autocoid, a paracoid, and an antioxidant vitamin. Journal of Pineal Research, 34: 75–78. doi: 10.1034/j.1600-079X.2003.02111.x
- Issue published online: 17 DEC 2002
- Article first published online: 17 DEC 2002
- Received May 3, 2002; accepted July 19, 2002.
- free radical;
- hormone melatonin;
Abstract: 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.