Synthesis and biological evaluation of substituted phenylpyrazole[4,5-b]oleanane derivatives as inhibitors of glycogen phosphorylase.

A series of substituted phenylpyrazole[4,5-b]oleanane derivatives have been synthesized and biologically evaluated as inhibitors of glycogen phosphorylase (GP). The structure of phenylpyrazole moiety in compound 17 was determined by ROESY. All of the synthesized oleanane derivatives were biologically evaluated against rabbit muscle GPa. Within this series of compounds, pyrazole triterpene 7 (IC(50) = 10.8 μM) exhibited slightly more potent activity than its parent compound 1. Preliminary SAR analysis of the pyrazoleoleanane derivatives as GP inhibitors is discussed.