Structure–activity relationships of xanthene carboxamides, novel CCR1 receptor antagonists Original Research Article

The structure–activity relationships of xanthene carboxamide derivatives on the CCR1 receptor binding affinity and the functional antagonist activity were described. Previously, we reported a quaternarized xanthen-9-carboxamide 1 as a potent human CCR1 receptor antagonist that was derived from a xanthen-9-carboxamide lead 2a. Further derivatization of 2a focusing on installing an additional substituent into the xanthene ring resulted in the identification of 2b–1 with IC50 values of 1.8 nM and 13 nM in the binding assay using human CCR1 receptors transfected CHO cells and in the functional assay using U937 cells expressing human CCR1 receptors, respectively.