Novel Small Molecule Inhibitors of Botulinum Neurotoxin A

描述(由申请人提供)：总体项目目标是开发一种口服活性小分子BONT/A抑制剂。BONT/A LC的神经元底物是25.000 mW的突触体相关蛋白(SNAP-25)。我们的假设是，小分子BONT/A抑制剂可以穿透神经元，防止SNAP-25被BONT LC切割，将为治疗毒素暴露前和毒素暴露后提供潜在的可能性。我们的策略一直是通过化学文库筛选和三维亚结构数据库挖掘相结合的方法，寻找适合于在合理的药物设计方案中进一步进行化学提纯的“类药物”小分子BONT/A LC抑制剂支架。通过这一过程，我们在酶和细胞检测中发现了几种低um效价的BoNT/A抑制剂，它们可以阻止其靶底物SNAP-25的BoNT/A细胞内蛋白分解。已确定的抑制剂类别是新的，并且不具有非药物样特征，如异羟肟酸和多肽骨架。这些经过验证的化学“HIT”系列将为开发有效、安全和口服的抗BONT/A药物奠定基础。我们将应用成熟的药物和组合化学技术、抑制剂-酶复合体X射线结晶学和基于结构的药物设计(SBDD)来快速合成和评估这些新验证的BONT/A抑制剂支架的衍生物。在迭代过程中，我们将通过测量衍生物的酶和细胞活性和特异性，探索专注的化合物文库，以寻找有助于更紧密结合和更有效地抑制BONT/A的特征。我们将确定与BONT活性部位结合的改进的抑制剂的X射线结构，并使用这些数据来开发改进的药效团模型，以指导进一步探索结构活性关系(SAR)。我们将评估化合物的最佳ADME(吸收、分布、代谢、消除)、药代动力学和生物利用度特性。具有足够的酶活性、细胞活性和ADME特性的化合物将被放大，并在BONT诱导的大鼠死亡模型中进行有效性测试。成功地将大鼠从BONT诱导的死亡中解救出来，将使化合物有资格成为体内验证的线索。我们将评估这些能够实现毒性和安全药理学的研究性新药(IND)的线索，以便将它们开发成适合人类临床试验的IND前临床候选药物。到这项拟议的研究和临床前开发计划结束时，我们整个项目的里程碑是提交一份IND，用于口服活性小分子BONT/A抑制剂的临床人体安全性评估。

DESCRIPTION (provided by applicant): The overall project goal is to develop an orally active small molecule BoNT/A inhibitor. The neuronal substrate for BoNT/A LC is synaptosomal-associated protein of 25.000MW (SNAP-25). Our hypothesis is that small molecule BoNT/A inhibitors which can penetrate the neuron, preventing SNAP-25 cleavage by the BoNT LC, will provide the potential for treatment of both pre- and post-toxin exposure. Our strategy has been to identify "drug-like" small molecule BoNT/A LC inhibitor scaffolds, through a combination of chemical library screening and 3D sub-structure database mining, suitable for further chemical refinement in a rational drug design program. Through this process, we have identified several BoNT/A inhibitors with low uM potencies in enzymatic and cell based assays, which prevent BoNT/A intracellular proteolysis of its target substrate SNAP-25. The identified inhibitor classes are novel and devoid of non-drug like features such as hydroxamic acid and peptidic backbones. These validated chemical "hit" series will form the basis for development of efficacious, safe and orally bioavailable drugs against BoNT/A. We will apply proven techniques of medicinal and combinatorial chemistry; inhibitor-enzyme complex X-ray crystallography and structure-based drug design (SBDD) to rapidly synthesize and evaluate derivatives of these new validated BoNT/A inhibitor scaffolds. In an iterative process, we will probe focused compound libraries for features contributing to tighter binding and more potent inhibition of BoNT/A by measuring the enzymatic and cellular activity and specificity of derivatives. We will determine the X-ray structures of improved inhibitors bound to the BoNT active site, and use the data to develop refined pharmacophore models to guide further probing of the structure activity relationship (SAR). We will assess compounds for optimal ADME (Absorption, Distribution, Metabolism, Elimination), pharmacokinetic and bioavailability properties. Compounds with sufficient enzymatic, cellular potency and ADME properties will be scaled-up and tested for efficacy in a BoNT induced rat death model. Successful rescue of rats from BoNT-induced death will qualify compounds as in vivo-validated leads. We will evaluate these leads for investigational new drug (IND) enabling toxicity and safety pharmacology in order to develop them into pre-IND clinical candidates, suitable for human clinical trials. By the end of this proposed research and pre-clinical development plan, our overall project milestone is to file an IND for the clinical human safety evaluation of an orally active small molecule BoNT/A inhibitor.