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An insight into the ameliorative effects of melatonin against chromium induced oxidative stress and DNA damage: a review

Chromium (Cr), a ubiquitous metal, has become a potent pollutant due to global industrialization, leading to pollution of air, water, and food that impacts human health. The most stable forms of Cr are Cr(III) and Cr(VI) (the major product of industrial activities). Cr(III) is a micronutrient essential for maintaining normal blood glucose and lipid profiles in our body but it can also form Cr (III)-DNA adducts. In addition, it directly produces reactive oxygen species (ROS) via Fenton and Haber-Weiss reactions; leading to tissue injuries. Cr (VI) has the capacity to generate Cr(V), Cr (IV), and Cr(III), respectively under suitable conditions. These intermediates also damage to biological macromolecules by interactions with several enzymatic and non-enzymatic antioxidants. For example, Cr(III) can make double DNA strands breaking to inhibit DNA replication, induce DNA oxidation, and DNA adducts formation. All of these lead to the development of malignancy. Melatonin, a potent radical scavenger as well as a metal chelator, effectively chelates Cr(VI) and prevents DNA oxidative damage. Melatonin can upregulate the gene expression of several antioxidant enzymes, and thereby, maintains cellular integrity from the oxidative stress. Thus, melatonin can be a prime molecule to protect against Cr(VI) induced cytotoxicity and genotoxicity. This review aims to highlight the potential benefits of melatonin on Cr(VI) induced oxidative stress and DNA damage.