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

Previously, we have reported the design and synthesis of 4-aryl-1H-1,2,3-triazoles as inhibitors of indoleamine 2,3-dioxygenase (IDO), a promising therapeutic target of cancer. Here, we present the structure-activity relationship and enzyme kinetic studies on a series of 4-aryl-1H-1,2,3-triazoles. Three compounds (1, 6, 8) were found to possess more IDO inhibitory potency than the most commonly used 1-methyltryptophan. The results from the structure-activity relationship and molecular docking studies indicated that an electron-withdrawing group with low steric hindrance near the NH group of triazoles was necessary for the IDO inhibition.