Hydrophilic ester-bearing chlorogenic acid binds to a novel domain to inhibit xanthine oxidase.
Caffeic acid is a xanthine oxidase (XO) inhibitor that binds to the molybdopterin region of its active site. Caffeic acid phenethyl ester (CAPE) has higher hydrophobicity and exhibits stronger inhibition potency toward XO. Chlorogenic acid is a quinyl ester of caffeic acid that has increased hydrophilicity and also shows stronger XO inhibitory activity compared with caffeic acid. Caffeic acid and CAPE showed competitive inhibition against XO, whereas chlorogenic acid displayed mixed-type inhibition, implying that it binds to sites other than the active site. Structure-based molecular modeling was performed to account for the different binding characteristics of the hydrophobic and hydrophilic esters of caffeic acid. Chlorogenic acid showed weak binding to the molybdopterin region of XO, while it more strongly bound the flavin adenine dinucleotide region than it did the molybdopterin region. These results provide the basis for interactions of caffeic acid analogues with XO via various binding domains.
Wang
Shwu-Huey
SH
Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
Chen
Chien-Shu
CS
Huang
Shih-Hao
SH
Yu
Szu-Hsu
SH
Lai
Zhi-Yang
ZY
Huang
Sheng-Tung
ST
Lin
Chun-Mao
CM