Synthesis and evaluation of 1-phenyl-1H-1,2,3-triazole-4-carboxylic acid derivatives as xanthine oxidase inhibitors.

This study mainly focused on the modification of the X2 position in febuxostat analogs. A series of 1-phenyl-1H-1,2,3-triazole-4-carboxylic acid derivatives (1a-s) with an N atom occupying the X2 position was designed and synthesized. Evaluation of their inhibitory potency in vitro on xanthine oxidase indicated that these compounds exhibited micromolar level potencies, with IC50 values ranging from 0.21µM to 26.13μM. Among them, compound 1s (IC50=0.21μM) showed the most promising inhibitory effects and was 36-fold more potent than allopurinol, but was still 13-fold less potent than the lead compound Y-700, which meant that a polar atom fused at the X2 position could be unfavorable for potency. The Lineweaver-Burk plot revealed that compound 1s acted as a mixed-type xanthine oxidase inhibitor. Analysis of the structure-activity relationships demonstrated that a more lipophilic ether tail (e.g., meta-methoxybenzoxy) at the 4'-position could benefit the inhibitory potency. Molecular modeling provided a reasonable explanation for the structure-activity relationships observed in this study.