Overview Free radicals are chemical compounds with unpaired electrons in the valence shell a cascade is initiated whereby a free radical steals an electron from a cellular molecule the intial free radical is quenched but has created another free radical results in cell membrane peroxidation, DNA and protein damage Causes of free radical generation radiation exposure metabolism of drugs (phase I) e.g.) acetaminophen redox reactions naturally as part of oxidative ATP generation nitric oxide transition metals e.g.) copper and iron leukocyte oxidative burst reperfusion after anoxia a major cause of injury after thrombolytic therapy carbon tetrachloride exposure solvent used in dry cleaning industry leads to hepatocyte damage and resultant fatty change Degradation of free radicals occus by enzymes catalase superoxide dismutase glutathione peroxidase spontaneous decay antioxidants vitamins A, C, E