Phenotypic screening of a Medicines for Malaria Venture compound library against Mycobacterium tuberculosis (Mtb) identified a cluster of pan-active 2-pyrazolylpyrimidinones. The biology triage of these actives using various tool strains of Mtb suggested a novel mechanism of action. The compounds were bactericidal against replicating Mtb and retained potency against clinical isolates of Mtb. Although selected MmpL3 mutant strains of Mtb showed resistance to these compounds, there was no shift in the minimum inhibitory concentration (MIC) against a mmpL3 hypomorph, suggesting mutations in MmpL3 as a possible resistance mechanism for the compounds but not necessarily as the target. RNA transcriptional profiling and the checkerboard board 2D-MIC assay in the presence of varying concentrations of ferrous salt indicated perturbation of the Fe-homeostasis by the compounds. Structure–activity relationship studies identified potent compounds with good physicochemical properties and in vitro microsomal metabolic stability with moderate selectivity over cytotoxicity against mammalian cell lines.

中文翻译：

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抗结核 2-吡唑基嘧啶酮：结构-活性关系和作用模式研究

对 Medicines for Malaria Venture 的抗结核分枝杆菌( Mtb )化合物库进行表型筛选，鉴定出一组具有泛活性的 2-吡唑基嘧啶酮。使用不同的结核分枝杆菌工具菌株对这些活性物质进行生物学分类，提出了一种新的作用机制。这些化合物对复制的Mtb具有杀菌作用，并保留了对Mtb临床分离株的效力。尽管选定的Mtb MmpL3 突变株表现出对这些化合物的耐药性，但针对 mmpL3 亚型的最低抑制浓度 (MIC) 没有变化，表明 MmpL3 突变是这些化合物的可能耐药机制，但不一定是靶点。在不同浓度的亚铁盐存在下，RNA 转录谱和棋盘 2D-MIC 测定表明这些化合物对 Fe 稳态的扰动。结构-活性关系研究确定了具有良好理化性质和体外微粒体代谢稳定性的有效化合物，对哺乳动物细胞系的细胞毒性具有中等选择性。