Spectroscopic study of quercetin and hesperetin interaction with bovine milk xanthine oxidase

Abstract

Objectives: Quercetin and hesperetin are natural flavonoids with many important therapeutic properties. The interaction of these polyphenolic compounds with bovine milk xanthine oxidase as one of their major target proteins was studied using fluorescence quenching method for the first time.Methods: ThisEnzyme (3.07--10-8M) incubated with varying concentrations of hesperetin and quercetin (0-100 ?M) for 5 min and the fluorescence spectra were recorded at 296, 303 and 310°K. Results: It was found that these compounds quenched the fluorescence of XO. The binding constants and the number of binding sites of quercetin and hesperetin with XO were obtained.It was shown that the fluorescence quenching of quercetin and hesperetin with xanthine oxidase occur through a static, static and dynamic mechanism, respectively. The thermodynamic parameters (enthalpy and entropy changes) were also calculated at different temperatures. Conclusion: Both hydrogen and hydrophobic binding are involved in the interaction of quercetin with xanthine oxidase and hydrophobic binding exists in the interaction of hesperetin with xanthine oxidase.