After inducing liver fibrosis, melatonin restored the redox balance by decreasing the levels of ROS, NADPH oxidase 4 (NOX4), iNOS, and MDA, and by rising the activity of several antioxidant enzymes, and the expression of SOD, CAT, and GSH (Chen et al., 2019; Colares et al., 2016; Das et al., 2017; Zaitone et al., 2011). The gene discussed is NOS2; the disease is Hepatic fibrosis.