Inhibition of chrysin on xanthine oxidase activity and its inhibition mechanism.
Chrysin, a bioactive flavonoid, was investigated for its potential to inhibit the activity of xanthine oxidase (XO), a key enzyme catalyzing xanthine to uric acid and finally causing gout. The kinetic analysis showed that chrysin possessed a strong inhibition on XO ability in a reversible competitive manner with IC50 value of (1.26±0.04)×10(-6)molL(-1). The results of fluorescence titrations indicated that chrysin bound to XO with high affinity, and the interaction was predominately driven by hydrogen bonds and van der Waals forces. Analysis of circular dichroism demonstrated that chrysin induced the conformational change of XO with increases in α-helix and β-sheet and reductions in β-turn and random coil structures. Molecular simulation revealed that chrysin interacted with the amino acid residues Leu648, Phe649, Glu802, Leu873, Ser876, Glu879, Arg880, Phe1009, Thr1010, Val1011 and Phe1013 located within the active cavity of XO. The mechanism of chrysin on XO activity may be the insertion of chrysin into the active site occupying the catalytic center of XO to avoid the entrance of xanthine and causing conformational changes in XO. Furthermore, the interaction assays indicated that chrysin and its structural analog apigenin exhibited an additive effect on inhibition of XO.
State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
Suyun
S
Lin
State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China. Electronic address: gwzhang@ncu.edu.cn.
Guowen
G
Zhang
College of Pharmacy, Nanchang University, Nanchang 330047, China.
Yijing
Y
Liao
State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
Junhui
J
Pan
D047310:Apigenin / Q000737:chemistry / Q000494:pharmacology; D001665:Binding Sites; D020134:Catalytic Domain; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology; D005419:Flavonoids / Q000737:chemistry* / Q000494:pharmacology*; D007700:Kinetics; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013816:Thermodynamics; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors* / Q000737:chemistry*
D004791:Enzyme Inhibitors; D005419:Flavonoids; C043561:chrysin; D047310:Apigenin; D014969:Xanthine Oxidase
Chrysin; Competitive inhibitor; Inhibition mechanism; Molecular simulation; Multispectroscopic methods; Xanthine oxidase