Changes in oxygen-metabolizing enzymes and lipid peroxidation in human erythrocytes as a function of age of donor.

We have studied the activities of enzymes, which afford protection against superoxide radical anion and hydrogen peroxide and estimated the content of malondialdehyde. Superoxide dismutase activity decreased slightly with advanced age of donors. The activities of catalase and peroxidases were higher in the erythrocytes of the middle age group and the old age group than in the young individuals. Thiobarbituric acid-reactive product was also significantly elevated in the aged donors. These results support the hypothesis that observed differences in the activities of enzymes and the level of malondialdehyde may contribute to the changes associated with aging, produced by the free radical reactions.