substances that decrease the frequency of mutations and inhibit the mutagenic effect of chemical or physical agents. Antimutagens may be arbitrarily divided into three groups. Those of the first group block the effect of automutagens, which arise naturally in the cells in the process of metabolism (antiautomutagens); an example of this is the enzyme catalase, which disrupts the mutagenic effect of hydrogen peroxide. These antimutagens assure the maintenance of a definite level of spontaneous mutations. The antimutagens of the second group diminish the effects of external, artificial physical (ionizing radiation, etc.) and chemical mutagens. Such antimutagens are sulfhydryl compounds, strong reducing agents of the type Na2S2O , certain alcohols, and carbonates. Antimutagens of these two groups may inhibit mutagens or compete with genetically important structures for interaction with a mutagen, or may act as reducing agents, and so forth. The third group includes enzyme systems that act directly on the level of hereditary structures, that is, to “correct” sections of the chromosome that have been damaged by a mutagen. The mutation effect may also be removed by physical effects of a given intensity (light, high or low temperatures, etc.).
IU. S. DEMIN