The Protective Effect Of Phenylethanoid Glycosides Torenoside B And Savatiside A On Alzheimer Disease

Objective: Oxidative stress caused by Beta amyloid protein may play an important role in the pathogenesis of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases. Aβ_25–35 is known to be directly responsible for the production of reactive oxygen species（ROS） and induction of intracellular calcium overload. Savatiside A（SA） and Torenoside B（TB） is extracted from a traditional herbal medicine Monochasma savatieri Franch, which has been shown to protect activity against oxidative stress in H9c2 cells. This study was designed to measuer the neuroprotective effect of SA and TB against Aβ_25–35-induced AD in vitro and in vivo.Methods: MTT assay was used to evaluate the effect of cytotoxicity on the SH-SY5 Y and PC12 cells induced by Aβ_25–35; The morphological change of SH-SY5 Y and PC12 cells were detected by Giemsa staining; SH-SY5 Y cells apoptosis were performed by internuclecsomal DNA degradation with agarose gel electrophoresis analysis; To explore the possible neuroprotection mechanisms of those compounds, the level of ROS/Ca2+ in cells was measured by flow cytometry analysis; The spatial and non spatial learning and memory of the mice were investigated with Morris water maze（MWM） test and Y maze test; HE and Nissl staining was used to analyze the pyramidal layer structure in the CA1 regions; Transmissionelectron microscopy analysis was used to explored ultrastructure of hippocampus neurons in mice; Western blotting was employed to determine alternations of Calnexin, P-AMPK1 and P-AMPK2 in SH-SY5Y（PC12） and Lipid peroxidation protein COX-2 in hippocampal tissue of mouse.Results: Exposure of SH-SY5 Y or PC12 cells to Aβ_25–35 caused a significant viability loss, cell apoptosis and increased the intracellular ROS elevation. However, pretreatment of the cells with SA and TB prior to Aβ_25–35 exposure ameliorated Aβ_25–35-induced cellular events noticeably. In addition, SA and TB also suppressed Aβ_25–35-induced intracellular calcium overload and the abnormal expression of calmodulin-related proteins. SA and TB can reduced the Aβ_25–35-induced increase of Calnexin activity. Furthermore, SA and TB also ameliorated the Aβ_25–35-induced P-AMPK1 increase in SH-SY5 Y or PC12 cells. In the mice models, SA and TB significantly attenuated cognitive deficits in the Morris water maze and Y maze test. SA and TB also attenuated neuronal damage of the CA1 regions. Meanwhile, SA also weakened the Aβ_25–35-induced increase of COX-2 activity in hippocampal tissue of mouse. Conelusions: Taken together, these data indicated that SA and TB protected nerve cells against Aβ_25–35-induced AD through its antioxidative potential, antiapoptotic and keeping steady of intracellular calcium. Our results strongly suggested that SA and TB might be effective in treating neurodegenerative diseases associated with oxidative stress.