Terpenoids. III: Synthesis and biological evaluation of 23-hydroxybetulinic acid derivatives as novel inhibitors of glycogen phosphorylase

Abstract A series of 23-hydroxybetulinic acid derivatives were prepared and tested in vitro as a new class of inhibitors of glycogen phosphorylase (GP). Within this series of compounds, 12b (IC 50  = 3.5 μM) is the most potent GPa inhibitor. The preliminary SAR results of the 23-hydroxybetulinic acid derivatives are discussed.