Siderophore Inhibitors for Tuberculosis that Block Mycobactin Biosynthesis

摘要 结核分枝杆菌(Mtb)是结核病(TB)的主要病原体，感染了超过三分之一的 目前已成为单一病原体导致传染病死亡的主要原因。MTB需要铁 并通过合成、分泌和重新摄取体内这种必需的微量营养素 铁载体或称为分枝杆菌蛋白的小分子铁络合剂。在初步研究中，使用 遗传方法，我们已经证明了mycobactin的生物合成对于小鼠的结核分枝杆菌感染是必不可少的。我们有 合成了一种选择性的霉菌蛋白生物合成纳米分子抑制剂SAL-AMS，其靶向是 MBTA酶，负责分枝杆菌菌素生物合成的第一步和关键步骤。的目标 这一应用是：1)显著提高我们的先导化合物SAL-AMS的体内疗效 通过对其药代动力学参数和效价的优化，2)更深入地阐明 结核分枝杆菌的作用和耐药机制，3)确定安全性和潜在的药物 相互作用，以及4)确定与其他结核病药物的相互作用效果(即协同作用)。我们将完成 通过追求三个具体目标，实现这一申请的总体目标。在目标1中，我们将进行迭代 基于结构的药物化学程序同时优化药代动力学(PK)参数和 使用包括氟化、结构简化等方法组合的全细胞活性 核苷，以及在抑制剂中引入构象约束。在目标2中，我们将进行生化 和细胞研究，以评估酶抑制、靶点参与、细胞积累和全细胞 对结核分枝杆菌和耐药菌株的活性。耐药株的产生和全基因组 测序将用于表征潜在的抗性机制并确定抗性 频率最后，将进行与各种一线和二线结核病药物的联合研究，以 评估协同效应的潜力。在目标3中，铁载体抑制剂将在体内进行评估，以确定它们的 完整的药动学参数，目标是改善体内分布体积(Vd)， 利用度(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 对照一组检测(HERG、CYP抑制、激酶组)，以确保安全性和选择性。活体内 疗效研究将使用结核病感染的小鼠模型进行。

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.