Siderophore Inhibitors for Tuberculosis that Block Mycobactin Biosynthesis

总结 结核分枝杆菌（Mtb）是结核病（TB）的主要病原体，感染超过三分之一的 目前，单一病原体是导致传染病死亡的主要原因。结核病需要铁 在体内通过合成、分泌和再摄取获得这种必需的微量营养素。 铁载体或称为分枝杆菌素的小分子铁螯合剂。在初步研究中， 通过遗传学方法，我们已经表明分枝杆菌素生物合成对于小鼠中的Mtb感染是必需的。我们有 合成了一种称为Sal-AMS的分枝杆菌素生物合成的选择性纳摩尔抑制剂， 酶MbtA，负责分枝杆菌素的第一个和关键的生物合成步骤。的目标 这些应用是：1）显著改善我们的先导化合物Sal-AMS的体内功效 通过优化其药代动力学参数和效力，2）更深入地阐明 Mtb的作用机制和耐药性，3）确定安全性特征和潜在的药物-药物 相互作用，以及4）确定与其他TB药物的相互作用（即协同作用）。我们将实现 本申请通过追求三个具体目标来实现总体目标。在aim 1中，我们将执行迭代 基于结构药物化学程序，以同时优化药代动力学（PK）参数， 全细胞活性的方法，包括生物学方法的组合，结构简化， 核苷，以及将构象限制引入抑制剂。在目标2中，我们将执行生化 和细胞研究，以评估酶抑制、靶向接合、细胞蓄积和全细胞 抗Mtb以及耐药菌株的活性。产生耐药菌株，然后进行全基因组 测序将用于表征潜在的耐药机制，并确定耐药性 频率.最后，将开展各种一线和二线结核病药物的联合研究， 评估协同增效的潜力。在目标3中，将在体内评估铁载体抑制剂以确定其在体内的活性。 完整的药代动力学参数，目的是改善分布容积（Vd）、固有 清除率（CL）和生物利用度（F）。我们将进行慢性毒性研究和评估化合物 对照一组试验（hERG、β-D抑制、激酶组），以确保安全性和选择性。体内 将使用TB感染的鼠模型进行功效研究。

SUMMARY Mycobacterium tuberculosis (Mtb), the principal etiological agent of tuberculosis (TB), infects over one-third of humanity and is now the leading cause of infectious disease mortality by a single pathogen. Mtb requires iron for survival and obtains this essential micronutrient in vivo through the synthesis, secretion, and re-uptake of siderophores or small-molecule iron chelators known as the mycobactins. In preliminary studies using a genetic approach, we have shown mycobactin biosynthesis is essential for Mtb infection in mice. We have synthesized a selective nanomolar inhibitor of mycobactin biosynthesis termed Sal-AMS that targets the enzyme MbtA, responsible for the first and committed biosynthetic step of the mycobactins. The objectives of this application are: 1) to dramatically improve upon the in vivo efficacy of our lead compound Sal-AMS through the optimization of its pharmacokinetic parameters and potency, 2) to more deeply illuminate the mechanism of action and resistance in Mtb, 3) to determine the safety profile and potential drug-drug interactions, and 4) to identify interactive effects with other TB drugs (i.e. synergy). We will accomplish the overall objectives of this application by pursuing three specific aims. In aim 1, we will carry out an iterative structure-based medicinal chemistry program to concurrently optimize pharmacokinetic (PK) parameters and whole-cell activity using a combination of approaches including fluorination, structural simplification of the nucleoside, and introduction of conformation constraints into the inhibitor. In aim 2, we will perform biochemical and cellular studies to evaluate enzyme inhibition, target engagement, cellular accumulation, and whole-cell activity against Mtb as well as drug-resistant strains. Generation of resistant strains followed by whole-genome sequencing will be used to characterize potential resistance mechanisms and determine the resistance frequency. Finally, combination studies with various first and second-line TB drugs will be undertaken to assess potential for synergy. In aim 3, the siderophore inhibitors will be assessed in vivo to determine their complete pharmacokinetic parameters with a goal to improve on the volume of distribution (Vd), intrinsic clearance (CL), and bioavailability (F). We will conduct chronic toxicity studies and evaluate compounds against a panel of assays (hERG, CYP inhibition, kinase panel) to ensure safety and selectivity. In vivo efficacy studies will be done using a murine model of TB infection.