Identification of a novel 4-aminomethylpiperidine class of M-3 muscarinic receptor antagonists and structural insight into their M-3 selectivity

摘要

Identification of a novel class of potent and highly selective M-3 muscarinic antagonists is described. First, the structure-activity relationship in the cationic amine core of our previously reported triphenylpropionamide class of M-3 selective antagonists was explored by a small diamine library constructed in solid phase. This led to the identification of M-3 antagonists with a novel piperidine pharmacophore and significantly improved subtype selectivity from a previously reported class. Successive modification on the terminal triphenylpropionamide part of the newly identified class gave 14a as a potent M-3 selective antagonist that had > 100-fold selectivity versus the M-1, M-2, M-4, and M-5 receptors (M-3: K-i = 0.30 nM, M-1/M-3 = 570-fold, M-2/M-3 = 1600-fold, M-4/M-3 = 140-fold, M-5/M-3 = 12000-fold). The possible rationale for its extraordinarily higher subtype selectivity than reported M-3 antagonists was hypothesized by sequence alignment of multiple muscarinic receptors and a computational docking of 14a into transmembrane domains of M-3 receptors.