Title:Inhibition of Xanthine Oxidase by 4-nitrocinnamic Acid: In Vitro and
In Vivo Investigations and Docking Simulations
Volume: 25
Issue: 4
Author(s): Jianmin Chen*, Sijin Yu, Zemin He, Danhong Zhu, Xiaozhen Cai, Zhipeng Ruan and Nan Jin
Affiliation:
- School of Pharmacy and Medical Technology, Putian University, Fujian, China
- Key Laboratory of Pharmaceutical
Analysis and Laboratory Medicine (Putian University), Fujian Province University, Fujian, China
Keywords:
Xanthine oxidase, 4-nitrocinnamic acid, cinnamic acid, derivatives, uric acid, hyperuricemia.
Abstract:
Background: Cinnamic acid and its derivatives have gained significant attention in
recent medicinal research due to their broad spectrum of pharmacological properties. However, the
effects of these compounds on xanthine oxidase (XO) have not been systematically investigated,
and the inhibitory mechanism remains unclear.
Objectives: The objective of this study was to screen 18 compounds and identify the XO inhibitor
with the strongest inhibitory effect. Furthermore, we aimed to study the inhibitory mechanism of
the identified compound.
Methods: The effects of the inhibitors on XO were evaluated using kinetic analysis, docking simulations,
and in vivo study. Among the compounds tested, 4-NA was discovered as the first XO
inhibitor and exhibited the most potent inhibitory effects, with an IC50 value of 23.02 ± 0.12
μmol/L. The presence of the nitro group in 4-NA was found to be essential for enhancing XO inhibition.
The kinetic study revealed that 4-NA inhibited XO in a reversible and noncompetitive
manner. Moreover, fluorescence spectra analysis demonstrated that 4-NA could spontaneously
form complexes with XO, referred to as 4-NA–XO complexes, with the negative values of △H
and ΔS.
Results: This suggests that hydrogen bonds and van der Waals forces play crucial roles in the
binding process. Molecular docking studies further supported the kinetic analysis and provided
insight into the optimal binding conformation, indicating that 4-NA is located at the bottom outside
the catalytic center through the formation of three hydrogen bonds. Furthermore, animal studies
confirmed that the inhibitory effects of 4-NA on XO resulted in a significant reduction of serum
uric acid level in hyperuricemia mice.
Conclusion: This work elucidates the mechanism of 4-NA inhibiting XO, paving the way for the
development of new XO inhibitors.