# Inhibition of Xanthine Oxidase by Four Phenolic Acids: Kinetic, Spectroscopic, Molecular Simulation, and Cellular Insights

## TL;DR

This study explores how four phenolic acids inhibit xanthine oxidase, a key enzyme in uric acid production, using various experimental and computational methods.

## Contribution

The study provides new insights into the inhibition mechanism and binding properties of phenolic acids on xanthine oxidase.

## Key findings

- All four phenolic acids exhibited mixed inhibition of xanthine oxidase through hydrophobic interactions.
- FA and CA showed greater structural stability in molecular dynamics simulations.
- FA, CA, and PA significantly reduced uric acid levels in the 25–100 μM range.

## Abstract

The inhibition mechanism and binding properties of four phenolic acids (ferulic acid (FA), p-coumaric acid (CA), gallic acid (GA), and protocatechuic acid (PA)) on xanthine oxidase (XOD) were investigated. All four phenolic acids acted via a mixed inhibition pattern, mainly influencing the hydrophobic regions and secondary conformation of XOD through hydrophobic bonding and hydrophobic association. Molecular dynamics simulations exhibited that the complexes of XOD with FA and CA revealed smaller radii of gyration (Rg) and solvent-accessible surface areas (SASA), along with lower variability in root-mean-square deviation (RMSD) and root-mean-square fluctuation (RMSF), collectively indicating greater structural stability. FA, CA, and PA significantly reduced uric acid (UA) concentration in the 25–100 μM range. Although GA only reduced UA levels in cell models at 25 μM, this effect was likely due to its larger polar surface area, which limits cellular uptake. Absorption, distribution, metabolism, excretion, and toxicity (ADMET) evaluation suggested that these phenolic acids have potential for development.