Melatonin, its metabolites and its synthetic analogs as multi-faceted compounds: antioxidant, prooxidant and inhibitor of bioactivation reactions.

It is known that melatonin (MLT) and some of its metabolites act as antioxidants by scavenging free radicals as well as increasing the activity of antioxidant enzymes in the body. MLT is suggested to exert beneficial effects via various mechanisms in the treatment of many diseases, such as cancer, neurodegenerative diseases, epilepsy, diabetes mellitus and obesity. People working in nightshift exhibit decreased MLT levels that are suggested to be related with increased risk of hormone-related diseases. Similarly blind people were found to have increased MLT levels protecting against many diseases. This review briefly summarizes the published reports supporting these beneficial effects of MLT. Furthermore the present review involves recent developments related to the antioxidant effect of remarkable and multi-faceted molecule MLT as well as its metabolites and its synthesized analogues. The role of MLT as an inhibitor of bioactivation reactions is also discussed.