Insights from multispectral and molecular docking investigation on the xanthine oxidase inhibition by 1,4-dicaffeoylquinic acid

Xanthine oxidase (XOD) is a key enzyme in the production of uric acid, related to the occurrence of hyperuricemia. In this study, the inhibitory mechanism of 1,4-dicaffeoylquinic acid (1,4-diCQA) on XOD was investigated. Kinetic analysis showed that 1,4-diCQA inhibited XOD (IC50: 7.36 +/- 0.63 mu M) in a reversible competitive mode. Fluorescence spectra revealed that hydrogen bonds and van der Waals forces played main roles in the binding of XOD and 1,4-diCQA. Circular dichroism showed that the contents of alpha-helix, beta-turn and random coil of XOD decreased while the beta-sheet content increased with the addition of 1,4- diCQA. Molecular docking revealed that 1,4-diCQA interacted with the active site of XOD via the key amino acid residues of Gln112, Gln1040, Thr1077, Ser1080, Ser1082 and Asp1084. These findings provide the mechanism of 1,4-diCQA on inhibiting XOD and further the application of 1,4-diCQA in preventing hyperuricemia. (C) 2020 Published by Elsevier B.V.