Neuroprotective oleanane triterpenes from the roots of Bupleurum chinense

The discovery of new natural compounds with pharmacological properties is an increasingly important field, and a continuous phytochemical investigation of the roots of Bupleurum chinense D.C. has led to the isolation of 17 triterpenoids, including three new oleanane triterpenes (1-3) together with 14 known ones. Their structures were determined on the basis of 1D and 2D NMR spectra as well as HR-ESI-MS data. The cytotoxicities of all compounds against five selected human cancer cell lines were assayed. Only compounds 9 and 14 exhibited moderate activities. Recently, a number of investigations have focused on the neuroprotective properties of triterpenoids in B. chinense. In order to expand our knowledge about this herb, the neuroprotective effects of compounds 1-17 against hydrogen peroxide (H2O2)-induced neuronal cell damage in human neuroblastoma SH-SY5Y cells were evaluated. Compounds 1-3, 6-7 showed significant neuroprotective effects against H2O2-induced SH-SY5Y cell death. Preliminary structure-activity relationships (SARs) between neuroprotective effects and the isolates were also discussed.