TP-0427736

7-Methoxy-6-[4-(4-methyl-1,3-thiazol-2-yl)-1H-imidazol-5-yl]-1,3-benzothiazole 11 (TASP0382088) was synthesized and evaluated as transforming growth factor-β (TGF-β) type I receptor (also known as activin receptor-like kinase 5 or ALK5) inhibitor. Compound 11, a potent and selective ALK5 inhibitor, exhibited good enzyme inhibitory activity (IC50=4.8 nM) as well as inhibitory activity against TGF-β-induced Smad2/3 phosphorylation at a cellular level (IC50=17 nM). The introduction of a methoxy group to the benzothiazole ring in 1 and the break up of the planarity between the imidazole ring and the thiazole ring improved the solubility in the lotion base of 11. Furthermore, the topical application of 3% 11 lotion significantly inhibited Smad2 phosphorylation in mouse skin at 8 h after application (71% inhibition, compared with vehicle-treated animals).

A series of 5-(1,3-benzothiazol-6-yl)-4-(4-methyl-1,3-thiazol-2-yl)-1H-imidazole derivatives was synthesized as transforming growth factor-β (TGF-β) type I receptor (also known as activin-like kinase 5 or ALK5) inhibitors. These compounds were evaluated for their ALK5 inhibitory activity in an enzyme assay and for their TGF-β-induced Smad2/3 phosphorylation inhibitory activity in a cell-based assay. As a representative compound, 16i was a potent and selective ALK5 inhibitor, exhibiting a good enzyme inhibitory activity (IC(50) = 5.5 nM) as well as inhibitory activity against TGF-β-induced Smad2/3 phosphorylation at a cellular level (IC(50) = 36 nM). Furthermore, the topical application of 3% 16i lotion significantly inhibited Smad2 phosphorylation in Mouse skin (90% inhibition compared with vehicle-treated animals).