YGsy2p-IN-1 is a potent inhibitor for yeast glycogen synthase 2 (yGsy2p) . yGsy2p-IN-1 is a competitive human glycogen synthase 1 (hGYS1) inhibitor with an IC50 of 2.75 μM and a Ki of 1.31 μM for wild-type hGYS1. yGsy2p-IN-H23 a pyrazole inhibitor, is used for glycogen storage diseases (GSDs) [1].