Protein tyrosine phosphatase 1B inhibitory effect by dammarane-type triterpenes from hydrolyzate of total Gynostemma pentaphyllum saponins

Three new dammarane-type triterpenes sapogenin, gypensapogenin E (1), gypensapogenin F (2) and gypensapogenin G (3), together with 12 known compounds were isolated from the hydrolyzed saponins from the of Gynostemma pentaphyllum. All the compounds were evaluated for inhibitory activity against PTP1B.