Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, USA.
Center for Discovery and Innovation, Hackensack Meridian Health, Nutley, NJ, USA.
Bioorg Med Chem. 2022 Nov 15;74:117046. doi: 10.1016/j.bmc.2022.117046. Epub 2022 Oct 7.
Tuberculosis (TB) remains a leading cause of infectious disease-related mortality and morbidity. Pyrazinamide (PZA) is a critical component of the first-line TB treatment regimen because of its sterilizing activity against non-replicating Mycobacterium tuberculosis (Mtb), but its mechanism of action has remained enigmatic. PZA is a prodrug converted by pyrazinamidase encoded by pncA within Mtb to the active moiety, pyrazinoic acid (POA) and PZA resistance is caused by loss-of-function mutations to pyrazinamidase. We have recently shown that POA induces targeted protein degradation of the enzyme PanD, a crucial component of the coenzyme A biosynthetic pathway essential in Mtb. Based on the newly identified mechanism of action of POA, along with the crystal structure of PanD bound to POA, we designed several POA analogs using structure for interpretation to improve potency and overcome PZA resistance. We prepared and tested ring and carboxylic acid bioisosteres as well as 3, 5, 6 substitutions on the ring to study the structure activity relationships of the POA scaffold. All the analogs were evaluated for their whole cell antimycobacterial activity, and a few representative molecules were evaluated for their binding affinity, towards PanD, through isothermal titration calorimetry. We report that analogs with ring and carboxylic acid bioisosteres did not significantly enhance the antimicrobial activity, whereas the alkylamino-group substitutions at the 3 and 5 position of POA were found to be up to 5 to 10-fold more potent than POA. Further development and mechanistic analysis of these analogs may lead to a next generation POA analog for treating TB.
结核病（TB）仍然是导致传染病相关死亡和发病的主要原因。吡嗪酰胺（PZA）是一线结核病治疗方案中的重要组成部分，因为它对非复制分枝杆菌（Mtb）具有杀菌活性，但它的作用机制仍然是个谜。PZA 是一种前体药物，在 Mtb 中由 pncA 编码的吡嗪酰胺酶转化为活性部分吡嗪酸（POA），而 PZA 耐药性是由于吡嗪酰胺酶的功能丧失突变引起的。我们最近表明，POA 诱导靶向蛋白降解酶 PanD，PanD 是辅酶 A 生物合成途径的关键组成部分，在 Mtb 中是必不可少的。基于 POA 的新作用机制以及与 POA 结合的 PanD 的晶体结构，我们使用结构解释设计了几种 POA 类似物，以提高效力并克服 PZA 耐药性。我们制备并测试了环和羧酸的生物等排体以及环上的 3、5、6 取代物，以研究 POA 支架的结构活性关系。所有类似物都进行了全细胞抗分枝杆菌活性评估，并用等温滴定微量热法评估了几种代表性分子对 PanD 的结合亲和力。我们报告说，环和羧酸的生物等排体类似物并没有显著增强抗菌活性，而 POA 的 3 和 5 位上的烷基氨基取代物的活性则比 POA 高 5 到 10 倍。这些类似物的进一步开发和机制分析可能会导致下一代 POA 类似物用于治疗结核病。
