Synthesis and SAR study of new thiazole derivatives as vascular adhesion protein-1 (VAP-1) inhibitors for the treatment of diabetic macular edema: Part 2

Novel thiazole derivatives were synthesized and evaluated as vascular adhesion protein-1 (VAP-1) inhibitors. Although our previous compound 1 showed potent VAP-1 inhibitory activity, the activity differed between humans and rats. This issue was overcome by a hybrid design using human VAP-1 specific inhibitor 2, which was found by high-throughput screening (HTS), a docking study of a human VAP-1 homology model, and an analysis of sequence information for humans and rats. As a result, we identified compound 35c, which showed strong VAP-1 inhibitory activity (human IC₅₀ of 20 nM; rat IC₅₀ of 72 nM) and significant inhibitory effects in the ex vivo test.