Dopamine D2-like Functionally Selective Agonists

我们已经使用双位设计成功地鉴定了高D3R选择性的化合物，其中包括一个高亲和力的初级药效团(PP)，如4-苯基哌嗪，连接到一个延伸的芳香胺官能团，该官能团占据一个次级结合口袋(SBP)，以提高亚型选择性。我们很想知道，这种药物设计方法是否可能针对更普遍的D2受体亚型(D2R)，以及已知的D2样激动剂的结构修改是否会为功能偏向和潜在治疗有用的新药靶点提供线索。在这项研究中，我们采用了我们的合成方法，使用了已知的D2-优先激动剂苏马尼罗作为PP，通过1和N-5位的烷基化增加了结构复杂性，并通过丁基连接链从这些位置延伸芳基酰胺来创建第一个二价类似物。通过这种方法，我们确定了完全有效的类似物和D2R优先的配体与扩展的芳基酰胺药效团。此外，利用苏马尼罗和部分类似物的分子模拟，我们开始计算探索这些配体在D2R和D3R之间的分子相互作用。基于广泛的放射性配基结合和功能研究，我们确认了探针依赖性的重要性，并确定苏马尼罗只有30倍的D2R选择性。重要的是，我们发现N-5位的修饰可以提高D2R亲和力，但不能提高选择性，即使在4-苯基哌嗪中扩展的芳胺取代基也能提供D3R选择性。这些研究证实，当SumaniRole是PP时，D3R SBP不是唯一访问的。此外，N-1位的替换似乎会导致这些类似物的疗效降低，特别是在D3R，这表明这里的替换影响了PP在OBS中的定位，并且亚型之间可能存在细微的差异。分子模拟证实了这一假设，并为进一步研究潜在的点位和功能偏向激动剂的苏马尼罗模板上的这两个位置提供了理论基础。 最近，我们已经将这类分子的SAR扩展到新的和功能偏向的D2受体选择性化合物。通过使用小分子SAR、计算建模和基于细胞的功能分析在原子水平上研究药物与蛋白质的相互作用，我们已经能够发现药物分子在正位结合部位(OBS)的姿势导致对D2或D3受体的选择性以及在D2R处的功能选择性，尽管这些受体亚型在这一区域具有很高的同源性。使用这种方法的进一步研究将揭示结构-功能信息，这些信息可用于未来提高治疗效果的分子的药物设计。我们最近研究了一种新型的结构模板，它将PP苏马尼罗与正变构调节剂或其他具有独特手性连接物的SP结合在一起。由此得到的对映体类似物是以GO蛋白为导向的，正在进行体内研究，以表征这些新化合物的行为特征。

We have successfully identified highly D3R-selective compounds using a bitopic design, which includes a high-affinity primary pharmacophore (PP), such as 4-phenylpiperazine, connected to an extended aryl amide functional group that occupies a secondary binding pocket (SBP) to enhance subtype selectivity. We were curious to learn if this drug design approach might be directed toward the more ubiquitous D2 receptor subtype (D2R) and further, if structural modifications of a known D2-like agonist would provide clues toward functionally biased and potentially therapeutically useful new drug targets. In this study, we took our synthon approach using the known D2-preferential agonist, sumanirole, as the PP, adding structural complexity through alkylation at the 1 and N-5-positions, and creating the first bivalent analogues by extending an aryl amide from these positions with a butyl linking chain. In this way, we identified fully efficacious analogues and D2R-preferential ligands with extended aryl amide pharmacophores. Moreover, using molecular simulations with sumanirole and selected analogues, we began to computationally explore the molecular interactions between these ligands at D2R and D3R. Based on extensive radioligand binding and functional studies we confirmed the importance of probe dependency and determined that sumanirole is only 30-fold D2R selective. Importantly, we discovered that modifications at the N-5 position could improve D2R affinity, but not selectivity, even with the extended arylamide substituents that in the 4-phenypiperazines confer D3R-selectivity. These studies confirm that when sumanirole is the PP, the D3R SBP is not uniquely accessed. Moreover, substitution at the N-1-position appears to result in lower efficacy, especially at D3R, for these analogues, suggesting that substitution here affects the positioning of the PP in the OBS and there may be subtle difference here between subtypes. Molecular simulations confirmed this hypothesis and provided rationale for further investigating these two positions on the sumanirole template for potential bitopic and functionally biased agonists. More recently, we have expanded the SAR of this class of molecules toward novel and functionally biased D2 receptor selective compounds. By investigating drug-protein interactions at an atomistic level using small molecule SAR, computational modeling and cell-based functional assays, we have been able to uncover drug molecule poses in the orthosteric binding site (OBS) that result in a preference for D2 or D3 receptor selectivity as well as functional selectivity at D2R, despite high homology in this region of these receptor subtypes. Further investigation using this approach will unveil structure-function information that can be utilized for future drug design of molecules with improved therapeutic efficacy. We have recently investigated a novel structural template that combines the PP sumanirole with a positive allosteric modulator or other SPs with unique and chiral linkers. The resulting enantiopure analogues are Go-protein biased and in vivo studies are underway to characterize the behavioral profile of these novel compounds.