Oleanane- and Ursane-Type Triterpene Saponins from Exhibit Neuroprotective Effects.

Six new pentacyclic triterpenoid saponins, centelloside F (), centelloside G (), 11--asiaticoside B (), 11--madecassoside (), 11(β)-methoxy asiaticoside B (), and 11(β)-methoxy madecassoside (), along with seven known ones, asiaticoside (), asiaticoside B (), madecassoside (), centellasaponin A (), isoasiaticoside (), scheffoleoside A (), and centelloside E (), were separated from the 80% MeOH extract of the whole plant of , which has been used as a medicinal plant and is now commercially available as a diatery supplement in many countries. Compounds and , and , and and are three pairs of isomers with oleanane- or ursane-type triterpenes as aglycones. The chemical structures of the new triterpene saponins were fully characterized by extensive analysis of their nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry data. The protective effects of compounds - on PC12 cells induced by 6-OHDA were screened, and compound displayed the best neuroprotective effect, with 91.75% cell viability at the concentration of 100 μM. Moreover, compound also attenuated cell apoptosis and increased the mRNA expression of antioxidant enzymes, including superoxide dismutase and catalase. Additionally, compound activated the phosphatidylinositol 3-kinase/Akt pathway, including PDK1, Akt, and GSK-3β. These findings suggested that triterpene saponins from were worthy of further biological research to develop new neuroprotective agents.