Background: Ascorbic acid (AA) is a powerful antioxidant. In the presence of free iron (Fefree), however, AA can act as a pro-oxidant and contribute to the production of hydroxyl radicals, which in turn may cause lipid peroxidation and protein oxidation. Cord plasma concentrations of AA are high in preterm (PT) infants, and Fefree is detectable in the plasma of many PT infants.

Aim: To determine whether the combination of Fefree and high AA concentrations is associated with increased lipid peroxidation and/or protein oxidation in cord plasma of PT infants.

Methods: Plasma concentrations of AA, Fefree (bleomycin assay), and markers of lipid peroxidation (F2-isoprostanes, F2IP) and protein oxidation (protein-carbonyls, Prot-CO) were measured in 29 PT infants(mean gestational age (GA) 29 weeks, mean birth weight 1390 grams) and 5 adult controls (nonsmokers). Stepwise multivariate linear regression analysis was performed.

Results: AA and F2IP, but not prot-CO were significantly higher in PT infants than in adults (table). For all PT infants(n=29), F2IP were positively correlated with both GA(P=0.002) and AA (P=0.02). However, in those infants with Fefree, (n=19), the correlation between F2IP and AA was not statistically significant (P=0.11), and there also was no independent effect of Fefree on F2IP (NS).

Table 1
Full size table

Conclusions: Both lipid peroxidation products and AA are significantly elevated in plasma of PT infants compared to adults. AA is positively correlated with F2IP in plasma of PT infants, but this relationship appears not to be due to a simple pro-oxidant interaction between AA and Fefree.