Development of M5 Selective Muscarinic Antagonists

描述（由申请人提供）：基于脑区定位、参与中枢多巴胺能通路的调节以及来自M5基因敲除小鼠的行为数据，M5毒蕈碱乙酰胆碱受体（mAChR）已成为药物滥用治疗的潜在靶点。然而，由于缺乏选择性配体，这种受体的确切生理作用及其药物开发潜力尚不明确。本发明的目的是开发新的M5受体拮抗剂。基于已报道的非选择性毒蕈碱拮抗剂，我们使用渐进的逐步结构修饰策略产生了70多种结构相关的类似物，从中确定了几种对M5 mAChR亚型具有更高选择性和效力的新线索。此外，我们已经构建了一个同源性模型的M5 mAChR的基础上新获得的晶体结构的B1肾上腺素能受体。在这次修订中，我们建议建立和验证同源模型的其他4 mAChR亚型使用报告的化合物。这些计算机模拟模型将用于虚拟文库筛选。设计了由9种不同结构支架组成的结构多样化的虚拟筛选文库，并预期将出现作为M5 mAChR的虚拟命中的高度选择性和有效的类似物。虚拟命中将在计算机模拟ADMET筛选程序中进行预评估，以将合成工作集中在可药用类似物上。将使用表达hM 1-hM 5的CHO细胞在受体结合试验中评价可药用虚拟命中。将在使用天然M5受体的功能试验中评价对M5具有选择性的类似物，还将在脱靶试验中评价铅类似物的体外心脏毒性（hERG试验）和神经毒性（多巴胺纹状体含量）。我们期待发现有前途的M5拮抗剂，这将是有用的药理学工具，并有潜力作为新的治疗药物用于治疗药物滥用。

DESCRIPTION (provided by applicant): M5 muscarinic acetylcholine receptors (mAChRs) have emerged as a potential target for the treatment of drug abuse, based on brain region localization, involvement in the regulation of central dopaminergic pathways, and behavioral data from M5-knockout mice. However, the exact physiological role of this receptor and its potential for pharmacotherapeutic development are ambiguous due to the lack of selective ligands. The purpose of the current proposal is to develop novel M5 receptor antagonists. Based on a reported nonselective muscarinic antagonist, we generated over 70 structurally-related analogs using a progressive step-by-step structural modification strategy from which several new leads with increased selectivity and potency for M5 mAChR subtypes have been identified. Further, we have constructed a homology model of M5 mAChR based on the newly available crystal structure of the b1 adrenergic receptor. In this revision, we propose to build and validate homology models for the other 4 mAChR subtypes using reported compounds. These in silico models will be used for virtual library screening. A structurally diversified virtual screening library, which consists of 9 different structural scaffolds, was designed and anticipate that highly selective and potent analogs as virtual hits for M5 mAChRs will emerge. The virtual hits will be pre-evaluated in in silico ADMET screening programs to focus the synthetic efforts on druggable analogs. Druggable virtual hits will be evaluated in receptor binding assays using CHO cells expressing hM1-hM5. Analogs selective for M5 will be evaluated in functional assays using native M5 receptors and lead analogs will be evaluated also in off-target assays, for in vitro cardiotoxicity (hERG assays) and neurotoxicity (dopamine striatal content). We anticipate the discovery of promising M5 antagonists, which will be useful pharmacological tools and have potential as novel therapeutic agents for the treatment of drug abuse.