Antigenotoxic effect of melatonin against mercuric chloride in human peripheral blood lymphocytes

Melatonin (MLT) is an extraordinary antioxidant, which plays an important role in reducing reactive oxygen species (ROS) by scavenging them directly or indirectly. Mercury (Hg) is a heavy metal, which induces cytogenetic alterations via various mechanisms, leading to genotoxicity. It induces genotoxicity by enhancing the ROS chiefly. In the present study, the antigenotoxic effect of MLT was evaluated against mercuric chloride (HgCl₂). All experiments were conducted in vitro in peripheral blood lymphocytes. Blood cultures were exposed to various concentrations of HgCl₂ (2.63, 6.57, and 10.52 microM) for 24 h to study a range of genotoxic parameters. MLT (0.2 mM) supplementation, alone and in combination with the high concentration of Hg, was administered to blood cultures for 24 h. Genotoxic parameters, such as chromosomal aberrations (CAs; structural aberrations (chromatid gaps and breaks, chromosomal gaps and breaks) and numerical aberrations), micronuclei (MNs), and comet assay, were evaluated and analyzed using suitable statistical analysis. Hg treatment revealed a significant increase in CAs, MNs, and comet length. Co-supplementation of MLT along with Hg showed marked protection of these genotoxic end points in treated cultures. In conclusion, our findings suggest that MLT protects against Hg-induced augmentation in genotoxic indices because of its antioxidant property.