New dammarane-type triterpenoids from the leaves of Panax notoginseng and their protein tyrosine phosphatase 1B inhibitory activity

BACKGROUND: Panax notoginseng has been used as a general tonic agent to invigorate human body for millennia in China and continued to be used until present. METHODS: Some chromatographic methods were performed to isolate pure triterpenoids, and their structures were determined by nuclear magnetic resonance (NMR) experiments. Anti-diabetes activities of isolated compounds were evaluated through their inhibitory activity of protein tyrosine phosphatase 1B (PTP1B) enzyme. RESULTS AND CONCLUSION: Three new dammarane-type triterpenoids, notoginsenoside-LX (1), notoginsenoside-LY (2), and notoginsenoside-FZ (3) together with eighteen known compounds were isolated from the Panax notoginseng leaves. The structure-activity relationship of the compounds with dammarane-type triterpenoids and their PTP1B inhibitory activity were also reported. Results showed that compounds 2, 15, 20, and 21 can significantly inhibit the enzyme activity of PTP1B in a dose-dependent manner, with inhibitory concentration 50 (IC(50)) values of 29.08 μM, 21.27 μM, 28.12 μM, and 26.59 μM, respectively. The results suggested that Panax notoginseng leaves might have potential as a new therapeutic agent for the treatment of diabetes.