Non-peptide Mu Opioid Receptor Selective Antagonists

描述（由申请人提供）：阿片类药物依赖是最严重的慢性和复发性成瘾性疾病之一。已经证明，对于许多临床可用的阿片类药物，它们的镇痛功能和它们臭名昭著的副作用（例如成瘾和滥用倾向）主要是由于它们与μ阿片受体（莫尔）的相互作用。我们的长期目标是开发高选择性的莫尔拮抗剂作为化学探针，研究莫尔构效关系，以协助开发副作用较少，成瘾和滥用倾向较低的新型潜在镇痛药。提出的研究背后的具体假设是，6-杂芳取代的纳洛酮胺衍生物可以作为莫尔的选择性拮抗剂。我们的假设是基于以下事实：第一，一个主要系列的配体设计和合成的6-杂芳取代的纳洛酮胺衍生物已显示出高选择性的莫尔。第二，这些配体中的一些对莫尔表现出强拮抗作用。第三，分子模拟研究表明，这些配体可能与受体的细胞外环（EL）结构域，特别是EL 2和EL 3具有特异性相互作用。已经发现，莫尔的EL 3对于莫尔选择性激动剂的结合是非常关键的。定点诱变研究表明，EL 3上的某些氨基酸残基可能是配体（包括激动剂和拮抗剂）对莫尔的选择性所必需的。基于这些观察，本建议的重点是合成和评价6-杂芳取代的纳洛酮胺衍生物作为莫尔非肽拮抗剂。具体目标是：1.基于已从初步合成和药理学筛选中鉴定的先导化合物，设计和合成作为μ阿片受体拮抗剂的新型化合物。同源建模的莫尔和对接的纳洛酮到莫尔模型允许的假设识别的独特的氨基酸残基的结合口袋相比，相应的（或保守的）位点的δ和κ阿片受体拮抗剂结合位点。设计、合成和测试了两个系列的新型配体，其通过携带独特的结构特征与莫尔的EL 3（和/或EL 2）相互作用来满足莫尔结合口袋的要求。初步研究中确定了两种先导化合物。基于这两个先导化合物的化学结构，设计了几个新的配体系列。为了实现这些新的配体，已经提出了化学合成路线。2.作为选择性莫尔拮抗剂合成的化合物的药理学评价将集中在体外放射性配体结合试验以确定亲和力和选择性，功能性35 S-GTP [3S]结合试验以确定功效，以及体内行为试验。3.将进行分子建模研究-辅助定点诱变研究，以验证配体的结合模式，并进一步表征莫尔的拮抗剂结合位点，用于下一代拮抗剂设计。我们的长期目标是开发高选择性的μ阿片受体非肽拮抗剂作为化学探针，研究其结构和功能关系，以帮助开发无成瘾和滥用倾向或较少成瘾和滥用倾向的潜在镇痛药。本研究计划的重点是合成和测试μ阿片受体非肽拮抗剂，其具有与受体的细胞外环区域相互作用的结构特征，我们预计这将赋予μ阿片受体高选择性。我们相信，这样的配体将是有用的重要药理学工具，研究μ阿片受体的结构与功能的关系。

DESCRIPTION (provided by applicant): Opioid dependence is one of the most serious chronic and relapsing addictive disorders. It has been proven that for many clinical available opiates, both their analgesic function and their notorious side effects (such as addiction and abuse liability) are primarily due to their interaction with the mu opioid receptor (MOR). Our long- term goal is to develop highly selective antagonists for MOR as chemical probes to study MOR structure- efficacy relationship to assist the development of novel potential analgesics with fewer side effects and less addiction and abuse liability. The specific hypothesis behind the proposed research is that 6-heteroaromatic substituted naltrexamine derivatives may act as selective antagonist of MOR. Our hypothesis is based on the following facts: First, a primary series of ligands designed and synthesized as 6-heteroaromatic substituted naltrexamine derivatives have shown high selectivity to MOR. Second, some of these ligands showed strong antagonism to MOR. Third, molecular modeling studies have showed that these ligands may have specific interaction with the extracellular loop (EL) domains of the receptor, especially EL2 and EL3. It has been found out that EL3 of the MOR is very critical for the binding of MOR selective agonists. Site-directed mutagenesis studies have revealed that certain amino acid residues on EL3 may be essential for ligand (including agonist and antagonist) selectivity to MOR. Based on these observations, the focus of this proposal is the synthesis and evaluation of 6-heteroaromatic substituted naltrexamine derivatives as MOR non-peptide antagonists. The specific aims are: 1. Design and synthesis of novel compounds as mu opioid receptor antagonists based on lead compounds that have been identified from the primary synthesis and pharmacological screening. Homology modeling of MOR and the docking of naltrexone into the MOR model allowed the hypothetical identification of the unique amino acid residues in the binding pocket compared with corresponding (or conserved) loci in the delta and kappa opioid receptor antagonist binding sites. Two series of novel ligands satisfying the requirement of the MOR binding pocket by carrying the unique structural features to interact with EL3 (and/or EL2) of MOR have been designed, synthesized and tested. Two lead compounds have been identified for the preliminary studies. Several new series of ligands have been designed based on the chemical structures of these two lead compounds. The chemical synthesis routes have been proposed in order to materialize these new ligands. 2. Pharmacological evaluation of the compounds synthesized as selective MOR antagonist will be focused on in vitro radioligand-binding assays to determine affinity and selectivity, functional 35S-GTP[3S]-binding assay to determine efficacy, and in vivo behavioral tests. 3. Molecular modeling study- assisted site-directed mutagenesis studies will be conducted to verify the binding mode of the ligands and further characterize the antagonist binding site of the MOR for the next generation antagonist design. PUBLIC HEALTH RELEVANCE Our long-term goal is to develop highly selective non-peptide antagonists for the mu opioid receptor as chemical probes to study its structure and function relationship in order to assist the development of the potential analgesics without or with less addiction and abuse liability. The focus of this research program is to synthesize and test mu opioid receptor non-peptide antagonists carrying structural features to interact with the extracellular loop region of the receptor, which we anticipate will impart high selectivity for the mu opioid receptor. We believe such ligands will be useful as important pharmacological tools to study the structure-function relationship of the mu opioid receptor.