Nine new nor-3,4-seco-dammarane triterpenoids from the leaves of Cyclocarya paliurus and their hypoglycemic activity

This manuscript describes the isolation of nine new nor-3,4- seco -dammarane triterpenoids , norqingqianliusus A-I ( 1 – 9 ) and one known nortriterpenoid ( 10 ) from Cyclocarya paliurus leaves. Norqingqianliusus A and B ( 1 and 2 ) possess a unique 3,4- seco -dammarane-type C 26 tetranortriterpenoid skeleton. The compounds were structurally characterized through modern spectroscopic techniques. Moreover, the potential mechanism of hypoglycemic activity was further explored by studying the effects on glucosamine-induced insulin resistant HepG2 cells. In vitro hypoglycemic effects of all of the isolates were investigated using insulin resistant HepG2 cells. The glucose consumption was significantly promoted by compound 10 , in a dose-dependent manner, thus alleviating damage in IR-HepG2 cells. Besides, it reduced the PEPCK and GSK3β gene expression, involved in glucose metabolism. The anti-diabetic effects of the plant, utilized traditionally, can hence be attributed to the presence of nor-3,4- seco -dammarane triterpenoids in the leaves.