Peroxynitrite and nitrogen dioxide radical (null)

Peroxynitrite (ONOO⁻) is a highly reactive, short-lived nitrogen species formed from the diffusion-controlled reaction of superoxide (O₂•⁻) and nitric oxide (•NO) in biological systems[1][3][7][9]. In aqueous solution, peroxynitrite exists in equilibrium with its weak acid (ONOOH, pKₐ ~6.8), decays rapidly, and is a potent oxidant and nitrating agent capable of modifying proteins, lipids, and nucleic acids—either directly or by generating secondary radicals like nitrogen dioxide (•NO₂) and hydroxyl radical (•OH)[1][3][4][5]. Nitrogen dioxide radical (•NO₂) is a major secondary product of peroxynitrite decomposition, itself a strong one-electron oxidant with selectivity for aromatic amino acids (notably causing tyrosine nitration), promoting protein and lipid damage and impacting cell signaling[1][3][4][6]. Both are not classical drug targets but are "reactive species" central to processes of oxidative/nitrosative stress, inflammation, neurodegeneration, cardiovascular pathology, and cancer where their toxic signatures (like nitrotyrosine) serve as biomarkers of tissue injury[1][3][4][9]. If you are building a structured database, these species should not be included as canonical targets, but as toxic products or contributors to disease mechanisms. Their inclusion as 'targets' is nonstandard and unorthodox, explaining the above attributes.

Other names

Peroxynitrite (ONOO⁻, peroxynitrite anion, peroxynitrous acid/ONOOH)Nitrogen dioxide radical (•NO₂, nitrogen dioxide, NO₂•)

Scavenging or decomposition of peroxynitrite (removal of reactive species, reduction in oxidative/nitrosative stress) Inhibition of formation (reducing superoxide or nitric oxide availability)