Uric acid is the end-product of purine nucleotide metabolism and an increase in uric acid concentration in the body results in hyperuricemia, ultimately leading to gout. However, uric acid is a potent antioxidant and interacts with reactive oxygen species (ROS) to be non-enzymatically converted to allantoin. Uric acid accounts for approximately 60 % of antioxidant capacity in the plasma; however, its contribution to tissue antioxidant capacity is unknown. In this study, the contribution of uric acid to tissue antioxidant capacity and its conversion to allantoin by scavenging ROS in tissue were examined. The results showed that a decrease in hepatic uric acid content via allopurinol administration significantly reduced hepatic total-radical trapping antioxidant parameter (TRAP) content in protein-free cytosol. Additionally, treating protein-free cytosol with uricase led to a further reduction of hepatic TRAP content. Allantoin was also detected in the solution containing protein-free cytosol that
reacted with ROS. These findings suggest that in the absence of protein, uric acid contributes greatly to antioxidant capacity in the liver, where uric acid is converted to allantoin by scavenging ROS.
Increased concentration of uric acid (UA) is positively associated with the clinical severity but negatively associated with the prognosis of heart failure (HF). However, data related to the association between UA concentration and N-terminal pro brain natriuretic peptide (NT-proBNP) are still lacking. The aim of the study was to analyze the relationships between UA, NT-proBNP, clearance of creatinine and NYHA function class and echocardiographic variables in the Slovak population of primary care patients diagnosed with HF. The association between UA and NT-proBNP was assessed by multivariate analysis. 848 patients (402 men, 446 women) with HF were included in the study. NT-proBNP correlated with UA in both men and women after adjustment based on age, BMI and glomerular filtration rate (r=0.263, p<0.0001; r=0.293, p<0.0001). UA concentration rose with the severity of the NYHA class and was significantly higher in patients with moderate and severe systolic dysfunctions as well as with diastolic dysfunction in the multivariate analysis. In conclusion, our study in Slovak population with HF has revealed a positive correlation between the concentration of UA and NT-proBNP, and the independency of this association on confounding factors. The results support the role of UA as a biochemical marker of HF severity and prognosis.