yGsy2p-IN-H23 is a potent and first-in-class inhibitor for yeast glycogen synthase 2 (yGsy2p) with an IC50 of 875 μM for human glycogen synthase 1 (hGYS1). yGsy2p-IN-H23 bounds within the uridine diphosphate glucose binding pocket of yGsy2p. yGsy2p-IN-H23 is used for the research of glycogen storage diseases (GSDs).IC50 & Target: IC50: 875 μM (hGYS1)In Vitro: yGsy2p-IN-H23 (compound H23) has IC50 values against either hGYS1Δ634S8,11N or wild-type hGYS1 were 161 μM and 875 μM, respectively. yGsy2p-IN-H23 exhibits IC50 values of 280 μM and 263 μM in the absence and presence of G6P for yGsy2p against yeast and human glycogen synthase (GS), respectively. yGsy2p-IN-H23 is not in direct competition with G6P.