Receptor-interacting protein kinase 2 (RIPK2) is a key mediator of nucleotide-binding oligomerization domain (NOD) cell signaling that has been implicated in various chronic inflammatory conditions. A new class of RIPK2 kinase/NOD signaling inhibitors based on a 3,5-diphenyl-2-aminopyridine scaffold was developed. Several co-crystal structures of RIPK2•inhibitor complexes were analyzed to provide insights into inhibitor selectivity versus the structurally related activin receptor-like kinase 2 (ALK2) demonstrating that the inhibitor sits deeper in the hydrophobic binding pocket of RIPK2 perturbing the orientation of the DFG motif. In addition, the structure-activity relationship study revealed that in addition to anchoring to the hinge and DFG via the 2-aminopyridine and 3-phenylsulfonamide, respectively, appropriate occupancy of the region between the gatekeeper and the αC-helix provided by substituents in the 4- and 5-positions of the 3-phenylsulfonamide were necessary to achieve potent NOD cell signaling inhibition. For example, compound 18t (e.g. CSLP37) displayed potent biochemical RIPK2 kinase inhibition (IC₅₀ = 16 ± 5 nM), >20-fold selectivity versus ALK2 and potent NOD cell signaling inhibition (IC₅₀ = 26 ± 4 nM) in the HEKBlue assay. Finally, in vitro ADME and pharmacokinetic characterization of 18t further supports the prospects of the 3,5-diphenyl-2-aminopyridine scaffold for the generation of in vivo pharmacology probes of RIPK2 kinase and NOD cell signaling functions.

受体相互作用蛋白激酶2（RIPK2）是核苷酸结合寡聚域（NOD）细胞信号传导的关键介体，已参与多种慢性炎症性疾病。基于3,5-二苯基-2-氨基吡啶骨架的新型RIPK2激酶/ NOD信号抑制剂被开发出来。分析了RIPK2•抑制剂复合物的几种共晶体结构，以了解抑制剂的选择性与结构相关的激活素受体样激酶2（ALK2）的关系，表明抑制剂位于RIPK2的疏水结合口袋中的位置更深，扰乱了DFG的方向主题。此外，结构-活性关系研究表明，除了分别通过2-氨基吡啶和3-苯基磺酰胺固定在铰链和DFG上，要实现有效的NOD细胞信号抑制，必须适当地占用网守和由3-苯基磺酰胺的4和5位上的取代基提供的αC-螺旋之间的区域。例如，化合物18t（例如CSLP37）在HEKBlue分析中显示出有效的生化RIPK2激酶抑制作用（IC ₅₀  = 16±5 nM），相对于ALK2的选择性> 20倍和有效的NOD细胞信号传导抑制（IC ₅₀  = 26±4 nM）。最后，体外ADME和18t的药代动力学特征进一步支持了3,5-二苯基-2-氨基吡啶支架用于RIPK2激酶和NOD细胞信号转导功能的体内药理学探针的前景。