Antioxidant Effect of Melatonin in Preterm Newborns

Abstract

Introduction. Preterm infants are at risk of free radical-mediated diseases from oxidative stress (OS) injury. Increased free radical generation has been demonstrated in preterm infants during the first seven days of life. Melatonin (MEL) is a powerful antioxidant and scavenger of free radicals. In preterm neonates, melatonin deficiency has been reported. Exogenous melatonin administration appears a promising strategy in the treatment of neonatal morbidities in which OS has a leading role. Objective. The aim was to evaluate plasma MEL concentrations and OS biomarkers in preterm newborns after early administration of melatonin. Methods. A prospective, randomized double-blind placebo-controlled pilot study was conducted from January 2019 to September 2020. Thirty-six preterm newborns were enrolled. Starting from the first day of life, 21 received a single dose of oral melatonin 0.5 mg/kg once a day, in the morning (MEL group); 15 newborns received an equivalent dose of placebo (placebo group). Samples of 0.2 mL of plasma were collected at 24 and 48 hours after MEL administration. Plasma concentrations of melatonin, non-protein-bound iron (NPBI), advanced oxidation protein products (AOPP), and F2-isoprostanes (F2-Isopr) were measured. Babies were clinically followed until discharge. Results. At 24 and 48 hours after MEL administration, the MEL concentrations were significantly higher in the MEL group than in the placebo group ( $52759.30\pm 63529.09$ vs. $28.57\pm 46.24$  pg/mL and $279397.6\pm 516344.2$ vs. $38.50\pm 44.01$  pg/mL, respectively). NPBI and AOPP did not show any statistically significant differences between the groups both at 24 and 48 hours. At 48 hours, the mean blood concentrations of F2-Isopr were significantly lower in the MEL group than in the placebo group ( $36.48\pm 33.85$  pg/mL vs. $89.97\pm 52.01$  pg/mL). Conclusions. Early melatonin administration in preterm newborns reduces lipid peroxidation in the first days of life showing a potential role to protect high-risk newborns. Trial Registration. This trial is registered with NCT04785183, Early Supplementation of Melatonin in Preterm Newborns: the Effects on Oxidative Stress.