Design, synthesis, and evaluation of novel 4-thiazolylimidazoles as inhibitors of transforming growth factor-β type I receptor kinase

Novel 4-thiazolylimidazoles were synthesized and evaluated as transforming growth factor-β (TGF-β) type I receptor (ALK5) inhibitors. A novel series of 4-thiazolylimidazoles was synthesized as transforming growth factor-β (TGF-β) type I receptor (also known as activin receptor-like kinase 5 or ALK5) inhibitors. These compounds were evaluated for their ALK5 inhibitory activity in an enzyme assay and their TGF-β-induced Smad2/3 phosphorylation inhibitory activity in a cell-based assay. N-{[5-(1,3-benzothiazol-6-yl)-4-(4-methyl-1,3-thiazol-2-yl)-1H-imidazol-2-yl]methyl}butanamide 20, a potent and selective ALK5 inhibitor, exhibited good enzyme inhibitory activity (IC50=8.2nM) as well as inhibitory activity against TGF-β-induced Smad2/3 phosphorylation at a cellular level (IC50=32nM).