Apoptosis signal-regulating kinase 1 (ASK1), a member of the mitogen-activated protein kinase (MAPK) family, is implicated in many human diseases. Here, we describe the structural optimization of hit compound 7 and conduct further structure-activity relationship (SAR) studies that result in the development of compound 19 with a novel indole-2-carboxamide hinge scaffold. Compound 19 displays potent anti-ASK1 kinase activity and stronger inhibitory effect on ASK1 in AP1-HEK293 cells than previously described ASK1 inhibitor GS-4997. Besides improved in vitro activity, compound 19 also exhibits an appropriate in vivo PK profile. In a dextran sulfate sodium (DSS)-induced mouse model of ulcerative colitis (UC), compound 19 shows significant anti-UC efficacy and markedly attenuates DSS-induced body weight loss, colonic shortening, elevation in disease activity index (DAI) and inflammatory cell infiltration in colon tissues. Mechanistically, compound 19 represses the phosphorylation of ASK1-p38/JNK signaling pathways and suppresses the overexpression of inflammatory cytokines. Together, these findings suggest that ASK1 inhibitors can potentially be used as a therapeutic strategy for UC.

凋亡信号调节激酶1（ASK1）是丝裂原激活的蛋白激酶（MAPK）家族的成员，与许多人类疾病有关。在这里，我们描述了命中化合物7的结构优化，并进行了进一步的结构-活性关系（SAR）研究，从而开发了带有新型吲哚-2-羧酰胺铰链支架的化合物19。与先前描述的ASK1抑制剂GS-4997相比，化合物19在AP1-HEK293细胞中显示出强大的抗ASK1激酶活性和对ASK1的更强抑制作用。除了改善体外活性外，化合物19还具有适当的体内活性PK配置文件。在右旋糖酐硫酸钠（DSS）诱导的溃疡性结肠炎（UC）小鼠模型中，化合物19显示出显着的抗UC功效，并显着减轻了DSS诱导的体重减轻，结肠缩短，疾病活动指数（DAI）升高和炎症结肠组织中的细胞浸润。从机理上讲，化合物19抑制ASK1-p38 / JNK信号通路的磷酸化，并抑制炎症细胞因子的过表达。这些发现共同表明，ASK1抑制剂可以潜在地用作UC的治疗策略。