ABSTRACT

Structural studies with an α subunit fragment of voltage-gated calcium (CaV) channels in complex with the CaVβ subunits revealed a high homology between the various CaVα-β subunits, predicting that targeting of this interface would result in nonselective compounds. Despite this likelihood, my laboratory initiated a rational structure-based screening campaign focusing on “hot spots” on the alpha interacting domain (AID) of the CaVβ2a subunits and identified the small molecule 2-(3,5-dimethylisoxazol-4-yl)-N-((4-((3-phenylpropyl)amino)quinazolin-2-yl)methyl)acetamide ( IPPQ ) which selectively targeted the interface between the N-type calcium (CaV2.2) channel and CaVβ. IPPQ (i) specifically bound to CaVβ2a; (ii) inhibited CaVβ2 ‘s interaction with CaV.2-AID; (iii) inhibited CaV2.2 currents in sensory neurons; (iv) inhibited pre-synaptic localization of CaV2.2 in vivo; and (v) inhibited spinal neurotransmission, which resulted in decreased neurotransmitter release. IPPQ was anti-nociceptive in naïve rats and reversed mechanical allodynia and thermal hyperalgesia in rodent models of acute, neuropathic, and genetic pain. In structure–activity relationship (SAR) studies focused on improving binding affinity of IPPQ , another compound (BTT-369), a benzoyl‐3,4‐dihydro‐1'H,2 H‐3,4'‐bipyrazole class of compounds, was reported by Chen and colleagues, based on work conducted in my laboratory beginning in 2008. BTT-369 contains tetraaryldihydrobipyrazole scaffold – a chemotype featuring phenyl groups known to be significantly metabolized, lower the systemic half-life, and increase the potential for toxicity. Furthermore, the benzoylpyrazoline skeleton in BTT-369 is patented across multiple therapeutic indications. Prior to embarking on an extensive optimization campaign of IPPQ , we performed a head-to-head comparison of the two compounds. We conclude that IPPQ is superior to BTT-369 for on-target efficacy, setting the stage for SAR studies to improve on IPPQ for the development of novel pain therapeutics.

摘要

对电压门控钙（CaV）通道的α亚基片段与CaVβ亚基复合的结构研究表明，各种CaVα-β亚基之间具有高度同源性，预示着靶向该界面将导致非选择性化合物。尽管有这种可能性，我的实验室还是开始了一项基于结构的合理筛选活动，重点关注CaVβ2a亚基的α相互作用域（AID）上的“热点”，并鉴定出小分子2-（3,5-二甲基异恶唑-4-基） -N-（（4-（（3-苯基丙基）氨基）喹唑啉-2-基）甲基）乙酰胺（IPPQ），其选择性靶向N型钙（CaV2.2）通道和CaVβ之间的界面。IPPQ （i）与CaVβ2a特异性结合；（ii）抑制CaVβ2与CaV.2-AID的相互作用；（iii）抑制感觉神经元中的CaV2.2电流；（iv）体内抑制CaV2.2的突触前定位; （v）抑制脊髓神经传递，导致神经递质释放减少。IPPQ在幼稚的大鼠中具有镇痛作用，在急性，神经性和遗传性疼痛的啮齿动物模型中可逆转机械性异常性疼痛和热痛觉过敏。在结构-活性关系（SAR）研究中，重点在于改善IPPQ的结合亲和力 ，另一种化合物（BTT-369）是苯甲酰基3,4-二氢-1'H，2 H-3,4'-联吡唑类化合物，根据我在实验室开始时所做的工作由Chen和同事报告在2008年，BTT-369包含四芳基二氢联吡唑支架-一种化学式，其特征在于已知具有明显代谢的苯基基团，可降低全身半衰期，并增加潜在的毒性。此外，BTT-369中的苯甲酰基吡唑啉骨架已获得多项治疗适应症的专利。在开始进行IPPQ的广泛优化之前，我们对两种化合物进行了直接对比。我们得出的结论是，IPPQ在靶点功效方面优于BTT-369，为SAR研究改善IPPQ奠定了基础 用于开发新型止痛药。