Abstract: Objective: To study the structures of ginseng glycopeptides, and to explore the protective effect on the apoptosis of PC12 cells treated with amyloid beta_25-35 (Aβ_25-35), and to lay a theoretical foundation for the development of ginseng anti-Alzheimer's disease(AD)drugs.Methods: The structures of ginseng glycopeptides were analyzed by reversed-phase high performance liquid chromatography coupled with Q Exactive Orbitrap mass spectrometry. The PC12 cells were divided into 6 groups, and treated with the medium including different concentrations (0, 6.25, 12.50, 25.00, 50.00, and 100.00 μmol·L^-1) of Aβ_25-35, and the survival rates of PC12 cells were measured by cell counting kit-8(CCK-8) method. The PC12 cells were divided into blank control group, model group,and ginseng glycopeptides administration group.The medium including 50.00 μmol·L^-1 Aβ_25-35 was added in model group,and different concentrations (0.03,0.10,0.30,and of 1.00 g·L^-1) ginseng glycopeptides+ 50 μmol·L^-1 Aβ_25-35were added in administration groups.The survival rates of PC12 cells were measured by CCK-8 method. The apoptotic rates of PC12 cells after treated with glycopeptides and Aβ_25-35 were detected by Annexin Ⅴ-FITC/PI method. The PC12 cells were divided into blank control group, model group (50.00 μmol·L^-1 Aβ_25-35) and different concentrations (0.10 and 0.30 g·L^-1) of ginseng glycopeptides administration groups;the percentages of PC12 cells in different cell cycles were tested by flow cytometry.Results: More than 20 glycopeptide structures were obtained, such as the peptide chain was NLSHYHSGSS, the glycosyl group was N1-HexNAc, and the peptide chain was SGSSSSSSSEDDGMGR, the glycosyl group was S6-HexNAc. When the concentration of Aβ_25-35 was 50 μmol·L^-1, the survival rate of PC12 was (55.45±2.34)% and the survival rate was significantly lower than that in blank control group (P<0.01). Compared with blank control group, the survival rate of the PC12 cells in model group was significantly decreased (P<0.01);compared with model group, the survival rates of the PC12 cells in administration groups were significantly increased (P<0.05). Compared with blank control group, the apoptotic rate of the PC12 cells in model group were increased (P<0.01);compared with model group, the apoptotic rates of the PC12 cells in administration groups were decreased (P<0.05).Compared with blank control group, the percentage of PC12 cells in S phase in model group was increased(P<0.05);compared with model group, the percentages of PC12 cells in S phase in administration groups were decreased (P<0.05).Conclusion: The structures of ginseng glycopeptides are obtained with mass spectrometry. Ginseng glycopeptides can effectively inhibit the apoptosis of PC12 cells treated with Aβ_25-35, and they have the neuroprotective effect;the anti-apoptotic activity effect may be related to the inhibition of S phase arrest.

Key words: Panax ginseng, glycopeptide, apoptosis, cell cycle, amyloid beta