Synthesis of 5-chloro-N-aryl-1H-indole-2-carboxamide derivatives as inhibitors of human liver glycogen phosphorylase a Original Research Article

A series of 5-chloro-N-aryl-1H-indole-2-carboxamide derivatives were prepared and evaluated as inhibitors of human liver glycogen phosphorylase a (hLGPa). One compound, 5-chloro-N-[4-(1,2-dihydroxyethyl)phenyl]-1H-indole-2-carboxamide (2f), inhibited hLGPa with an IC50 of 0.90 μM. The pyridine analogue of 2f showed inhibitory activity of glucagon-induced glucose output in cultured primary hepatocytes with an IC50 of 0.62 μM and oral hypoglycemic activity in diabetic db/db mice. Crystallographic determination of the complex of 2f with hLGPa showed binding of the inhibitor in a solvent cavity at the dimer interface, with the two hydroxyl groups making favorable electrostatic interactions with hLGPa.