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Bilirubin and ascorbate antioxidant activity in neonatal plasma
V Gopinathan1, N J Miller, A D Milner
1Free Radical Research Group, UMDS-Guy's Hospital, London, UK.
Insights
Premature infants have lower antioxidant capacity at birth. While ascorbate levels rise, total antioxidant status improves post-partum, with bilirubin playing a key antioxidant role.
Area of Science:
- Neonatal Medicine
- Biochemistry
- Pediatric Research
Background:
- Extremely low birth weight premature infants possess limited antioxidant defenses.
- Antioxidant components not crossing the placenta until the third trimester impact neonatal status.
Purpose of the Study:
- To compare total antioxidant activity and individual antioxidant concentrations in premature neonates versus term infants.
- To investigate changes in antioxidant status and bilirubin levels post-partum.
Main Methods:
- Plasma samples from premature neonates (27±2 weeks gestation) and term babies (38-41 weeks gestation) were analyzed.
- Total antioxidant activity and specific antioxidant concentrations were measured.
- Bilirubin levels were assessed in both groups.
Main Results:
- Premature neonates exhibited elevated plasma ascorbate at birth but lower overall antioxidant status compared to term infants.
- Post-partum, ascorbate levels normalized, and plasma bilirubin increased significantly in both groups.
- Premature neonates showed increased total plasma antioxidant status by 5 days post-partum.
Conclusions:
- Bilirubin is a significant plasma antioxidant, as evidenced by its direct correlation with total antioxidant activity in term infants.
- Premature infants' antioxidant capacity undergoes dynamic changes post-birth, with bilirubin contributing to overall status.
Abstract:
Extremely low birth weight premature infants have been known for many years to have limited antioxidant protective capacity, especially with reference to those antioxidant components which do not cross the placenta until the third trimester of gestation. In this study the total antioxidant activity and the concentrations of individual antioxidants in plasma from premature neonates (27 +/- 2 weeks gestation) compared to term babies (38-41 weeks gestation) have been examined. The results show elevated levels of ascorbate at birth in the plasma of premature neonates compared with those of term babies, but the total plasma antioxidant status of the premature babies is significantly lower than that of term babies. At 5 days post-partum the ascorbate levels are within the normal adult range and plasma bilirubin levels are considerably enhanced in both groups, while the total plasma antioxidant status of the premature neonates has increased. Analysis of the relationship between the total plasma antioxidant activity and the bilirubin concentration show a direct, highly significant correlation for the term group, r2 = 0.774, consistent with significance of bilirubin as a plasma antioxidant.