Noise-induced hearing loss in the 21st century: A research and translational update

Figure 2 Mechanism of oxidative cellular damage. Mechanism of oxidative cellular damage. Reactive oxygen species (ROS, including superoxide anion, O₂^·-, and hydroxyl radical, ·OH), reactive nitrogen species (RNS, nitrogen dioxide radical, NO₂^·), and lipid peroxides are generated as result of oxidation of oxygen (O₂) to superoxide anion by multiple cellular oxidases. Oxidases convert oxygen to O₂^·-, which is then dismutated to H₂O₂ by superoxide dismutase (SOD). H₂O₂ can be converted to H₂O by catalase or glutathione peroxidase (GSH-Px) or to hydroxyl radical (·OH) after reaction with Fe²⁺. In addition, O₂^·- reacts rapidly with nitric oxide (NO) to generate peroxynitrite (OONO^-). This further leads to production of NO₂^· and cellular damages through membrane lipid peroxidation and oxidation of DNA and proteins.