METABOLISM OF REACTIVE OXYGEN SPECIES

The paper reviews present opinions on important reactive oxygen specie s- ROS (superoxide anionradical, peroxy anion, hydroxy radical and sin glet oxygen). The sources of ROS (physical reactions, chemical reactio ns, enzymes and several proteins) are described. The roles of certain chemicals (iron, quinones and azo compounds) end the role of several e nzymes (cytochrome P450, NADPH cytochrome P450, cytochrome oxidase and xanthin oxidase) are discussed in more detail. In the biological mate rial, ROS can be inactivated by enzymic or non-enzymic mechanisms. The enzymic reactions described in this review include those catalyzed by superoxide dismutase (CuZn, Mn, Fe), catalase, glutathion peroxidase, cytochrome c peroxidase and DT-diaphorase (quinone reductase). In the non-enzymic protective mechanisms, the most important chemicals capab le to inactivate ROS are glutathione, beta-tocopherol, ascorbic acid, alpha-carotene, EDTA, mannitol, ethanol and others. The authors briefl y outline toxic effects of ROS in biological processes. Hydroxy radica l is considered as the most toxic ROS for its high electrophilicity an d reactivity. The effects of ROS on the cell and various cellular mole cules including DNA are mentioned and the role od ROS in a series of s evere human diseases (myocardial infarction, diabetes, chemical carcin ogenesis, and others) are discussed.