Structure-activity relationship and enzyme kinetic studies on 4-aryl-1H-1,2,3-triazoles as indoleamine 2,3-dioxygenase (IDO) inhibitors

► A series of 4-aryl-1H-1,2,3-triazoles were evaluated as IDO inhibitors. ► Three compounds (1, 6, 8) possessed more IDO inhibitory potency than 1-MT. ► A small electron-withdrawing group near the triazole NH was required for inhibition.