UC Irvine

Melatonin is an indoleamine with the chemical name N-acetyl-5-methoxytryptamine and is found in animals, plants, and bacteria. It has endocrine properties in both animals and plants. It is biosynthesized from the neurotransmitter, serotonin, which in turn is made from the essential amino acid, tryptophan. Because its 5-hydroxy and charged amino groups are both acetylated, it is a relatively nonpolar compound. In mammals, melatonin has several roles; it is involved in circadian regulation and modulation of reproductive and immune responses, mood, and aging. It is produced by the pineal gland and several peripheral tissues, notably the gut. Because it is liberated into the bloodstream from the pineal, it can be considered a systemic hormone. Levels of melatonin vary diurnally, being highest during hours of darkness, and also vary throughout the life cycle, being lowest among the elderly. This chapter focuses on recent findings suggesting a variety of therapeutic applications and supporting the safety of exogenously supplied melatonin. The potential molecular mechanisms underlying these potentially clinically beneficial uses are also discussed.