Bilirubin, the end product of heme catabolism, is generally regarded as a potentially cytotoxic, lipid-soluble waste product that needs to be excreted. However, bilirubin has been demonstrated to possess antioxidant properties as a chain breaking antioxidant and a scavenger of peroxyl radicals. Theses properties may be best evidents in neonates who may have undeveloped antioxidant enzymatic defenses. The aim of this study, therefore, was to evaluate the correlation between serum bilirubin and total antioxidant status in healthy term newborns.

Three groups were established: cord blood group (N=27), in which samples were collected of cord blood after birth; 24 hours group (N=37), in which infant's blood was collected at 24 hours of life; 48 hours group (N=23), in which infant's blood was collected at 48 hours of life.

Serum total bilirubin levels and total antioxidant status were evaluated in each sample. Total antioxidant status was assessed by means of inhibiton of the radical cation Abts+ (produced by the incubation of Abts with a peroxidase and H202) by the plasma antioxidants.

The results were: BT=1,2±0,6 mg/dl and TAS=2,04±0,80 mmol/l in cord blood samples; BT=5,0±1,9 mg/dl and TAS=2,34±1,23 mmol/l in 24 hours group; BT=6,1±3,4 mg/dl and TAS=3,42±1,15 mmol/l in 48 hours group. We obtained a positive correlation between serum bilirubin and total antioxidant status.

Conclusion: The data support the idea of a “beneficial” role for bilirubin as a physiological antioxidant.