ABSTRACT. To obtain a profile of erythrocyte antioxidant defense potential during late fetal development, we studied selected antioxidant parameters in blood samples from 65 neonates with birth wt between 520 and 4210 g and from 12 healthy adults. Erythrocyte superoxide dismutase activity did not change significantly with maturation and no significant differences were observed among preterm infants grouped in increasing birth wt categories, term neonates, and adults. Erythrocyte catalase and glutathione peroxidase, as well as plasma vitamin E levels, showed highly significant positive correlations ( p < 0.001) with increasing fetal wt and gestational age; by term, CAT activity reached a level similar to the adult control group, but glutathione peroxidase activity, as well as plasma vitamin E levels, were markedly lower in all the preterm and in the term groups than in adults ( p < 0.01). Erythrocyte glutathione S-transferase activity showed a negative correlation with increasing gestational age ( p < 0.01) and the adult values were considerably lower than any of the neonatal levels ( p < 0.001). The role of glutathione Stransferase in erythrocyte metabolism remains obscure. Maturational changes in the activity of the red cell enzymes that were studied and in the plasma vitamin E level were apparent from about 31-36 wk of gestation, suggesting that the stimulation for these changes may have commenced from about 28-31 wk. (Pediatr Res 26: 366-369, 1989) Abbreviations CAT, catalase SOD, superoxide dismutase GSH-Px glutathione peroxidase GSH-Px[H202], glutathione peroxidase with hydrogen peroxide as substrate GSH-Px[t-bh], glutathione peroxidase with t-butyl hydroperoxide as substrate GST, glutathione S-transferase The evolution of oxidative metabolic processes within mammalian cells has necessitated the concomitant development of mechanisms to protect vital cell components against oxygeninduced damage that could result from oxygen free-radical species produced during metabolism. These antioxidant systems include both enzymatic and nonenzymatic mechanisms. Vitamin E appears to be the most significant non-enzymatic antioxidant, and CAT, SOD, and selenium-dependent GSH-Px are believed to be the primary enzymatic systems; however, a role

The glutathione S-transferases (GST) are a group of enzymes present in a number of tissues, including liver and RBC's. They initiate detoxification of endogenous and exogenous substances by conj ugation with glutathione, and might act as storage proteins by binding nonsubstrate compounds such as heme and bilirubin.