ABSTRACT
Aim: To search for novel modulators of glycogen metabolism through structural modifications of natural pentacyclic triterpenes. Methods: A series of N-heterocyclic derivatives were synthesized by fusing indole, qui-noxaline and pyrazine rings with A-ring of oleanolic and ursolic acids. The compounds were biologically evaluated for their inhibitory activity against rabbit muscle glycogen phosphorylase. Results and Conclusion: Twelve heter-ocyclic triterpene derivatives were synthesized and their structures were confirmed by IR, ~1H NMR, ~(13)C NMR and MS. Except for compound 12, all of the compounds exhibited glycogen phosphorylase inhibitory activity with IC_(50) values in the range of 14-252 μmol/L Among this series of compounds, compound 15 showed the best potency with IC_(50), of 14 μmol/L