Oxidants and human disease: some new concepts.

Oxidant species such as superoxide radical (O.2-), hydrogen peroxide (H2O2), hydroxyl radical (HO.), and lipid peroxides (LOOH) are becoming increasingly implicated in human disease. However, the question of whether such oxidants are a major cause of tissue injury in human disease or are merely produced during such injury has been difficult to answer because of inadequate experimental techniques, and possibly because of an overemphasis on lipid peroxidation as a mechanism of oxidant injury. Recent developments in methodology, in our understanding of the primary mechanism of oxidant toxicity to cells, and in concepts of antioxidant protection are reviewed. Good evidence now exists for some role of oxidant damage to tissues in the pathology of several human diseases, including rheumatoid arthritis, reperfusion injury, immune injury to lung and kidney, and cerebral trauma or ischemia. These have led to promising suggestions for new therapeutic approaches.