Structure–Activity Relationship in Pyrazolo[4,3‑<i>c</i>]pyridines, First Inhibitors of PEX14–PEX5 Protein–Protein Interaction with Trypanocidal Activity

Trypanosoma protists are pathogens leading to a spectrum of devastating infectious diseases. The range of available chemotherapeutics against Trypanosoma is limited, and the existing therapies are partially ineffective and cause serious adverse effects. Formation of the PEX14–PEX5 complex is essential for protein import into the parasites’ glycosomes. This transport is critical for parasite metabolism and failure leads to mislocalization of glycosomal enzymes, with fatal consequences for the parasite. Hence, inhibiting the PEX14–PEX5 protein–protein interaction (PPI) is an attractive way to affect multiple metabolic pathways. Herein, we have used structure-guided computational screening and optimization to develop the first line of compounds that inhibit PEX14–PEX5 PPI. The optimization was driven by several X-ray structures, NMR binding data, and molecular dynamics simulations. Importantly, the developed compounds show significant cellular activity against Trypanosoma, including the human pathogen Trypanosoma brucei gambiense and Trypanosoma cruzi parasites.锥虫（Trypanosoma）原生生物是一类病原体，可引发一系列毁灭性的感染性疾病。目前针对锥虫的化疗药物种类有限，且现有疗法存在部分无效、引发严重不良反应的问题。PEX14–PEX5复合物的形成对于蛋白质输入至寄生虫的糖酵解体（glycosome）至关重要。这一转运过程对寄生虫的代谢至关重要，若转运失败会导致糖酵解体酶类的定位错误，对寄生虫造成致命影响。因此，抑制PEX14–PEX5蛋白-蛋白相互作用（protein–protein interaction, PPI）是影响多条代谢通路的极具吸引力的策略。本研究采用结构导向的计算机筛选与优化策略，开发出首批可抑制PEX14–PEX5蛋白-蛋白相互作用的化合物。该优化过程依托多项X射线晶体结构、核磁共振结合数据以及分子动力学模拟得以推进。值得注意的是，所开发的化合物对锥虫展现出显著的细胞活性，其中包括人类病原体冈比亚锥虫（Trypanosoma brucei gambiense）与克氏锥虫（Trypanosoma cruzi）。