[Free radical oxidation and the mechanisms of antioxidant defense in normal cells and tumor diseases (a lecture)].

The paper gives update on free radical oxidation and an antioxidant defense system in normal cells and cancers. It describes steps of oxidative stress: the emergence of free radicals, the development of chain reactions, and their inhibition by enzymatic and nonenzymatic reactions. A role of iron is shown in lipid peroxidation. The characteristics of major natural antioxidants and their implication in the regulation of the oxidant-antioxidant system in oncological care are given.