Free radical

Free radicals are highly reactive molecular species that contain one or more unpaired electrons in their atomic or molecular orbitals. Major examples include reactive oxygen species (ROS) such as superoxide, hydroxyl, and peroxyl radicals, and reactive nitrogen species (RNS) like nitric oxide[1][3][5][7]. Free radicals are produced both physiologically (mitochondrial electron transport, immune cell activation, signal transduction) and pathologically (exposure to toxins, inflammation). They indiscriminately react with proteins, lipids, and nucleic acids, often causing cellular damage through oxidation, DNA fragmentation, and structural modifications. However, free radicals also play crucial roles as signaling molecules, regulating processes like cell growth, apoptosis, synaptic plasticity, and immune responses[2][3][6]. Imbalance in free radical production and antioxidant defense leads to oxidative stress, which is implicated in numerous diseases including cancer, neurodegenerative disorders, cardiovascular diseases, diabetes, and inflammatory conditions[1][3][5][7]. There is no single receptor or protein called "Free radicals," and they do not constitute a defined therapeutic target in the sense of a receptor, enzyme, or transporter. Thus, the designation "Free radicals / Multiple non-specific targets" is not a specific or correct molecular target; instead, it refers to a group of highly reactive chemical species that exert biological effects via multiple, non-specific interactions with macromolecules in the cell and can affect diverse signaling and damage pathways across different cellular compartments.

Other names

Reactive oxygen species (ROS)Reactive nitrogen species (RNS)Oxygen free radicalNitric oxide radicalSuperoxide radicalHydroxyl radicalPeroxyl radicalAlkoxyl radical

Free radical scavenging; Inhibition of radical formation; Chelation of transition metals; Upregulation of endogenous antioxidant defense systems; Modulation of redox-sensitive signaling pathways