Oxidizing agents or electron-accepting molecules in chemical reactions in which electrons are transferred from one molecule to another (oxidation-reduction). In vivo, it appears that phagocyte-generated oxidants function as tumor promoters or cocarcinogens rather than as complete carcinogens perhaps because of the high levels of endogenous antioxidant defenses. It is also thought that oxidative damage in joints may trigger the autoimmune response that characterizes the persistence of the rheumatoid disease process.
Chemical substances having an oxygen molecule that is a by-product of photochemical smog.
A molecule that causes biological oxidation in which oxygen is added to or electrons removed from a substance. Oxygen-free radicals are highly toxic atoms and chemical groups produced by intracellular activity in various disease processes and by poisons, radiation, smoking and other pollutants. Anti-oxidants such as beta-carotene can neutralize these radicals.