Design, Synthesis, and Biological Evaluation of Novel 3-Aryl-4-(1H-indole-3yl)-1,5-dihydro-2H-pyrrole-2-ones as Vascular Endothelial Growth Factor Receptor (VEGF-R) Inhibitors

In this study we report on the design, synthesis, and biological evaluation of pyrrole-2-one 2 to be a highly potent VEGF-R2/3 inhibitor with IC50 of 31/37 nM. The novel 3,4-diaryl-2H-pyrrole-2-ones were designed on the basis of the modeled binding mode of the corresponding 1H-pyrrole-2,5-dione (maleimide) VEGF-R2/3 inhibitor 1 indicating two H-bond ligand−protein interactions in the ATP pocket for the amide 2 but not for the isomer 3. Flexible synthetic routes to 3,4-diaryl-2H-pyrrole-2-ones and structure−activity relationships for the compounds in a panel of 24 therapeutically relevant protein kinases (IC50 values) are presented. Accordingly to the in vitro data, compounds 1 and 2 were found to possess highly potent antiangiogenic activities in the cellular HLMEC sprouting assay and also slightly induced apoptosis in HDMECs whereas 3 was determined to be significantly less active. Hence, the pyrrole-2-one moiety was dissected from the corresponding maleimide protein kinase inhibitor as a suitable key pharmacophore.