Reactive oxygen species

Written By: Ehsan Jahandarpour

Reactive oxygen species (ROS) are highly reactive chemicals formed from O2. Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen. The reduction of molecular oxygen (O2) produces superoxide (•O−2), which is the precursor to most other reactive oxygen species: O2 + e− → •O−2 Dismutation of superoxide produces hydrogen peroxide (H2O2): 2 H+ + •O−2 + •O−2 → H2O2 + O2 Hydrogen peroxide in turn may be partially reduced, thus forming hydroxide ions and hydroxyl radicals (•OH), or fully reduced to water: H2O2 + e− → HO− + •OH2 H+ + 2 e− + H2O2 → 2 H2O