Melatonin and its metabolites: new findings regarding their production and their radical scavenging actions.

Abstract

This review summarizes some of the recent findings concerning the long-held tenet that the enzyme, N-acetyltransferase, which is involved in the production of N-acetylserotonin, the immediate precursor of melatonin, may in fact not always control the quantity of melatonin generated. New evidence from several different laboratories indicates that hydroxyindole-O-methyltransferase, which O-methylates N-acetylserotonin to melatonin may be rate-limiting in some cases. Also, the review makes the point that melatonin's actions are uncommonly widespread in organs due to the fact that it works via membrane receptors, nuclear receptors/binding sites and receptor-independent mechanisms, i.e., the direct scavenging of free radicals. Finally, the review briefly summarizes the actions of melatonin and its metabolites in the detoxification of oxygen and nitrogen-based free radicals and related non-radical products. Via these multiple processes, melatonin is capable of influencing the metabolism of every cell in the organism.

Therapeutic effect of perinatal exogenous melatonin on behavioral and histopathological changes and antioxidative enzymes in neonate mouse model of cortical malformation

“…It plays a role in some physiological functions, such as the regulation of physiological cycles, reproduction, circadian rhythm, and the neuroendocrine system (Gitto et al, 2013;Tomas-Zapico and Coto-Montes, 2005). Melatonin prevents lipid peroxidation and decreases mitochondrial hydroperoxide levels (Reiter et al, 2007). Evidence shows that melatonin can be effective as a neuroprotective drug for treatment of neurological diseases, such as Alzheimer's disease, Huntington's disease, and amyotrophic lateral sclerosis (Pandi-Perumal et al, 2013).…”

Melatonin‐mediated Bim up‐regulation and cyclooxygenase‐2 (COX‐2) down‐regulation enhances tunicamycin‐induced apoptosis in MDA‐MB‐231 cells

“…Melatonin, an indolamine derived from the amino acid tryptophan, controls important physiological functions including seasonal reproduction and circadian rhythms [1,2]. Numerous investigations have documented that melatonin may be an attractive candidate as an antitumor agent or for combined therapy because of its endogenous free radical scavenging activity and oncostatic properties [3][4][5][6][7][8][9]. Many studies have related its oncostatic and antitumor features with its ability to induce apoptosis and inhibit angiogenesis and metastasis [10][11][12][13][14][15].…”

Melatonin mitigates oxidative damage and apoptosis in mouse cerebellum induced by high‐LET56Fe particle irradiation

“…It has been over a decade since melatonin was discovered to be a free radical scavenger by Tan et al [20]. Presently, large varieties of evidences are available to document the broad spectrum antioxidant function of melatonin [21,22]. Neuroprotective potential of melatonin has also been suggested in many experimental as well as clinical studies [23,24].…”