Hydroxyl radical and peroxynitrite (OH/ONOO-)

Hydroxyl radical (•OH) and peroxynitrite (ONOO⁻) are highly reactive oxygen and nitrogen species (RONS) that serve as significant mediators of oxidative and nitrosative stress (Pacher et al., 2007, Physiological Reviews). The hydroxyl radical is an exceptionally potent oxidant produced primarily through the Fenton reaction, causing immediate and non-specific damage to DNA, lipids, and proteins (Halliwell & Gutteridge, 2015, Free Radicals in Biology and Medicine). Peroxynitrite is formed by the diffusion-controlled reaction between superoxide and nitric oxide; it acts as a strong oxidizing and nitrating agent, often identified by the presence of 3-nitrotyrosine residues on proteins (Beckman & Koppenol, 1996, American Journal of Physiology). These species are implicated in the pathogenesis of numerous conditions, including stroke, amyotrophic lateral sclerosis (ALS), and cardiovascular diseases, where they drive cellular apoptosis and tissue necrosis (Radi, 2018, Journal of Biological Chemistry). Pharmacological intervention typically involves small-molecule scavengers like edaravone, which is clinically used to treat ALS and acute ischemic stroke by neutralizing hydroxyl radicals (Watanabe et al., 1994, Journal of Pharmacology and Experimental Therapeutics). Ebselen and other glutathione peroxidase mimics are also employed to target peroxynitrite-mediated damage (Sies, 1993, Free Radical Biology and Medicine). This entry is considered composite as it includes two distinct chemical species often targeted by the same class of antioxidant drugs.

Other names

Reactive oxygen speciesReactive nitrogen speciesROSRNSFree radicalsOxidants•OHONOO-

Radical scavenging and neutralization of reactive oxygen and nitrogen species to prevent oxidative damage to cellular components.