Melatonin antioxidant properties

Ressmeyer, A. R Mayo, J. C., Zelosko, V. et al. (2003). Antioxidant properties of the melatonin metabolite N -acetyl-S-melhoxykynuramine (AMK) scavenging of free radicals and prevention of protein destruction. Redox Rep. 8, 205 13. 

The antioxidant properties of melatonin include scavenging free radicals and the regulation of the activity of antioxidant and pro-oxidant enzymes. It seems the potential application of melatonin in an antioxidant therapy could be complicated by the pharmacokinetic behavior of the molecule, which is subjected to a limited bioavailability and plasma half-life after oral administration [62],... 

Due to its free-radical scavenger and antioxidant properties, multiple melatonin-related compounds such as melatonin metabolites and synthetic analogues are under investigation to determine which exhibit the highest activity with the lowest side effects. 

Propolis, melatonin, resveratrol and J-carotene have been used in the treatment of inflammatory conditions, with both local and systemic applications [177]. The antioxidant property of propolis, melatonin, resveratrol and P-carotene could be attributed to its radical scavenging ability [178], which is better than the antioxidant property of vitamin C [179]. The anti-inflammatory property of propolis, melatonin, resveratrol and P-carotene has also been widely investigated in the literature [180]. 

Tan, D. X., Reiter, R. J., Manchester, L. C. et al. (2002). Chemical and physical properties and potential mechanisms melatonin as a broad spectrum antioxidant and free radical scavenger. Curr. Top. Med. Chem. 2, 181-97. 

Plasma levels of melatonin could not be delegate of its concentration in tissues [63], and its half-life in the target tissues could be much lower than expected. The availability of new compounds having the beneficial properties of melatonin, but revealing different pharmacokinetic properties could therefore be useful in the search for good antioxidant efficiency. 

The mechanism of melatonin s interaction with reactive species probably involves donation of an electron to form the melatoninyl cation radical or through a radical addition at the site C3. Other possibilities include hydrogen donation from the nitrogen atom or substitution at position C2, C4, and C7 and nitrosation [169]. The mechanisms by which melatonin protects against LP most likely involve direct or indirect antioxidant and free-radical scavenging activities of this indoleamine [169,171]. 2-Phenyl indole derivatives have redox properties because of the presence of an electron-rich aromatic ring system that allows the indoleamine to easily function as an electron donor. For these derivatives, the possible antioxidant mechanism might be most probably toward carbon-centered radicals described by Antosiewicz et al. [172]. 

Serotonin has been reported to function as a local antioxidant. The anti-oxidative properties of serotonin as well as of melatonin have been well documented.6 10 A discussion of the antioxidative actions of L-tryptophan and its metabolites is included in Chapter 9. 

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