Glycogen phosphorylase inhibitory effects of 2-oxo-1,2-dihydropyridin-3-yl amide derivatives

Discovery of new nanomolar inhibitors of GPa: Extension of 2-oxo-1,2-dihydropyridinyl-3-yl amide-based GPa inhibitors

Glycogen Phosphorylase (GP) is a functionally active dimeric enzyme, which is a target for inhibition of the conversion of glycogen to glucose-1-phosphate. In this study we report the design and synthesis of 14 new pyridone derivatives, and seek to extend the SAR analysis of these compounds. The SAR revealed the minor influence of the amide group, importance of the pyridone ring both spatially around the pyridine ring and for possible π-stacking, and confirmed a preference for inclusion of 3,4-dichlorobenzyl moieties, as bookends to the pyridone scaffold. Upon exploring a dimer strategy as part of the SAR analysis, the first extended 2-oxo-dihydropyridinyl-3-yl amide nanomolar based inhibitors of GPa (IC₅₀ = 230 and 260 nM) were identified.

The glycogen phosphorylase inhibitor 2-(3-benzylamino-2-oxo-1,2-dihydropyridin-1-yl)-N-(3,4-dichlorobenzyl)acetamide

The molecular structure of the title compound, C21H19Cl2N3O2, a potent glycogen phosphorylase a (GPa) inhibitor (IC50of 6.3 µM), consists of four distinct conjugated π systems separated by rotatable C—C bonds at the methylene groups. Molecules are linked into dimers disposed about a crystallographic centre of symmetry through a cyclic N—H...O hydrogen-bonding motif [graph setR22(10)]. These dimers are further connected along the crystallographiccaxis by N—H...O hydrogen bonding between the amide groups [graph setC(4)]. A comparison of this structure with that of the monohydrate of the significantly less active analogue (S)-2-(3-benzylamino-2-oxo-1,2-dihydropyridin-1-yl)-N-(2-hydroxy-1-phenylethyl)acetamide (IC50of 120 µM) is presented.