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) [1].