Free Radicals and Related Reactive Species

Reactive oxygen and nitrogen species (ROS/RNS) are collective terms that refer to a number of oxygen- or nitrogen-containing reactive species. They are produced from various cellular pathways as well as exogenous sources. ROS/RNS are able to cause damage to a variety of biomolecules, including lipids, proteins, and nucleic acids, leading to tissue injury and disease processes. Under certain circumstances, the well-controlled production of ROS/RNS also fulfils important physiological roles, including antimicrobial activity and participation in cell signaling. The biological effects of ROS/RNS, including both beneficial and detrimental effects are dependent on the types of ROS/RNS and their concentrations and duration of exposure, as well as the types of tissues/cells that the ROS/RNS are produced from or act on. The causal or contributing role of ROS/RNS in various diseases makes it necessary to devise strategies to mitigate the tissue injury and therefore protect against the disease process. Use of exogenous compounds with antioxidant properties and upregulation of endogenous cellular antioxidant enzymes by chemical inducers are among the potential approaches to the intervention of diseases with augmented ROS/RNS as underlying mechanisms.

Keywords: Alkoxyl radical, Hydrogen disulfide, Hydrogen peroxide, Hydroxyl radical, Hypochlorous acid, Nitric oxide, Ozone, Peroxyl radical, Peroxynitrite, Singlet oxygen, Superoxide.