Molecular modeling of flavonoids that inhibits xanthine oxidase.
The inhibition of xanthine oxidase activity by various flavonoids was assessed. All of the tested flavonoids were competitive inhibitors, and from the kinetic analysis suggested that flavonoids bind to the reactive site. To further understand the stereochemistry between these flavonoids and xanthine oxidase, structure-based molecular modeling was performed. Apigenin was the most potent inhibitor which showed the most favorable interaction in the reactive site. The bicyclic benzopyranone ring of apigenin stacked with phenyl of Phe 914, and the phenolic group stretched to the space surrounding with several hydrophobic residues. Quercetin and myricetin composed a 3-hydroxyl group on benzopyranone which resulting in reduction of binding affinity. The phenolic group of genistein positioned in opposite orientation comparison with apigenin, and resulted in a weaker interaction with xanthine oxidase. Isovitexin showed the weakest inhibitory effect among the compounds tested. The bulky group of sugar in isovitexin may hamper its interaction with xanthine oxidase.
Lin
Chun-Mao
CM
Institute of Biochemistry and Molecular Biology, College of Medicine, National Taiwan University, No. 1, Section 1, Jen-Ai Road, Taipei, Taiwan, ROC.
Chen
Chien-Shu
CS
Chen
Chien-Tsu
CT
Liang
Yu-Chih
YC
Lin
Jen-Kun
JK
D001665:Binding Sites; D001667:Binding, Competitive; D004249:DNA Damage; D005419:Flavonoids / Q000737:chemistry* / Q000494:pharmacology; D018922:HL-60 Cells; D006801:Humans; D008958:Models, Molecular; D009716:Numerical Analysis, Computer-Assisted; D017382:Reactive Oxygen Species / Q000378:metabolism; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors*
D005419:Flavonoids; D017382:Reactive Oxygen Species; D014969:Xanthine Oxidase