Molecules or ions formed by the incomplete one-electron reduction of oxygen. These reactive oxygen intermediates include SINGLET OXYGEN; SUPEROXIDES; PEROXIDES; HYDROXYL RADICAL; and HYPOCHLOROUS ACID. They contribute to the microbicidal activity of PHAGOCYTES, regulation of SIGNAL TRANSDUCTION and GENE EXPRESSION, and the oxidative damage to NUCLEIC ACIDS; PROTEINS; and LIPIDS.

Synonyms: 0, Oxygen, Active, Reactive Oxygen Species, Pro Oxidant, Pro-Oxidant, Pro Oxidants, Active Oxygen, Oxygen Species, Reactive, Oxygen Radicals, Pro-Oxidants