Design, synthesis, biological evaluation and molecular modeling of novel 2-amino-4-(1-phenylethoxy) pyridine derivatives as potential ROS1 inhibitors.

With the aim of discovering potential and selective inhibitors targeting ROS1 kinase, we rationally designed, synthesized and evaluated two series of novel 2-amino-pyridine derivatives with 1-phenylethoxy at C-3 and C-4 position. The enzymic assays results indicated that six of the new compounds 13b-13d and 14a-14c showed remarkably higher inhibitory activities against ROS1 kinase. The most promising compounds, 13d and 14c displayed the most desired ROS1 inhibitory activity with IC50 values of 440 nM and 370 nM respectively. Furthermore, 13d and 14c displayed ROS1 inhibitory selectivity of about 7-fold and 12-fold, relative to that of ALK sharing about 49% amino acid sequence homology in the kinase domains. They also showed good anti-proliferative effects against ROS1-addicted HCC78 cell lines with the IC50 values of 8.1 μM and 65.3 μM, respectively. Moreover, molecular docking and molecular dynamics simulation studies disclosed that compound 14c and 13d shared similar binding poses with Crizotinib except the selective binding site of ROS1. It also gave a probable molecular explanation for their activity and selectivity, which the methoxyl group in benzene ring was the crucial to the selectivity to ROS1 versus ALK.