Generation of Reactive Oxygen Species in Biological Systems

Reactive oxygen species include oxygen-derived free radicals (superoxide, hydroxyl radical, nitric oxide) and non-radical oxygen derivatives of high reactivity (singlet oxygen, hydrogen peroxide, peroxynitrite, hypochlorite). The main routes of their formation in living organisms include interaction of physical agents with cells and organisms, autoxidation of biochemical intermediates and xenobiotics, and biochemical synthesis for the sake of defense or signaling.