The Effectiveness Study Of Polysaccharides And Its Components From Ginseng On Alzheimer’s Disease

Ginseng is a traditional Chinese medicine with many pharmacological activities,which has been used for2000years. It has been reported that ginseng exertstherapeutic effect on many diseases, such as cancer, diabetes and cardiovasculardisease. Meanwhile, ginseng could improve the central nervous system (CNS),strengthen the immunological system and possess the antioxidant activity. There aremany chemical components extracted from ginseng, such as saponin, polysaccharides,volatile oil, amino acid, polypeptide and protein. For a long time, ginsenoside hasbeen considered as the active component to protect the CNS, while few study aboutthe neuroprotective effect of polysaccharides of ginseng has been reported. However,as a main component of ginseng, its content accounts for20%approximately and itspharmaceutical activities are various and widely accepted. Therefore, it’s necessary tostudy on the neuroprotective effect of polysaccharides of ginseng.Alzheimer’s disease (AD) is a neurodegenerative disease characterized by senileplaques, neurofibrilly tangles and neuron loss. Otherwise, AD is represented clinicallyby progressive learning and memory impairment, cognitive deficits and languagedisorder. The pathogenesis of AD is complicated which has not been explainedclearly.The aim of our research was to study the protective effect of ginsengpolysaccharides on the central nervous system in vivo. First, memory injured miceinduced by scopolamine was used. Morris water maze was used to study the behaviorchanging, and the activity of AchE was analyzed to study the probable mechanism ofglycopeptide on learning and memory disorder. Second, the protective effect of threedoses of ginseng polysaccharides (GP-1) on Aβ25-35-induced Alzheimer’s diseasewas studied. The learning and memory ability of the rats was evaluated by Morriswater maze test. The expressions of MAP2, CDK5, P-tau-Thr231and NF-κBp65onrats’ hippocampus were determined by the immunohistochemical method, which wasused to study the probable mechanism of ginseng polysaccharides on AD. Third,GP-2, GP-3and GP-4were resulted from the separation of GP-1. Morris water mazewas used to compare the therapeutic effect of the four fractions on Aβ-induced Alzheimer’s disease model of rats.Methods:1．Effectiveness study of ginseng glycopeptide on scopolamine induced learningand memory disorders in mice(1) Ethological test (Morris water maze test): place navigation, spatial probe(2) The assay of AchE activity2．Effectiveness study of ginseng polysaccharides （GP-1）on Aβ25-35-inducedAlzheimer’s disease model in rats(1) Determine the molecular weight, monosaccharide composition, proteincontent, Total carbohydrate and uronic acid contents of GP-1(2) Ethological test (Morris water maze test): place navigation, spatial probe(3) HE staining of the hippocampus of rats’ brains(4) Determination of the expression on the hippocampus of rats’ brains: MAP2,CDK5, P-tau-Thr231and NF-κBp653．Effectiveness study of ginseng polysaccharides fractions of Aβ25-35-inducedAlzheimer’s disease(1) The extraction of each components of ginseng polysaccharides: GP-1isseparated with the activated carbon column, H2O、10%and60%ethanol were used asthe elution in order, GP-2and GP-3are in collected elution of10%and60%ethanol,respectively. After dialyzing (10kD), the GP-4is attained from the dialysis fluid.(2) Determine the molecular weight, monosaccharide composition, proteincontent, Total carbohydrate and uronic acid contents of GP-2, GP-3and GP-4(3) Ethological test (Morris water maze test): place navigation, spatial probeResults：1．Effectiveness study of ginseng glycopeptide on scopolamine induced learningand memory disorders in mice(1) The result of Morris water maze test show that, ginseng glycopeptides couldreverse the prolonged escape latency induced by scopolamine when compared withthe model group.(2) Ginseng glycopeptide could inhibit the activity of AchE in the brain of mice.2. Effectiveness study of ginseng polysaccharides （GP-1）on Aβ25-35-inducedAlzheimer’s disease model in rats (1) GP-1mainly consisted of two oligosaccharides of which the molecularweight were672Da (38%) and331Da (61%). GP-1was composed of mannose,rhamnose, xylose, glucose, galactose and arabinose with a molar ratio of2.30:4.72:0.95:87.21:1.05:1.53.(2) The result of Morris water maze test show that high-dose GP-1(80mg/kg)could remarkably shorten the escape latency on the3rd and4th day and increase thecross-platform number and the ratio of platform quadrant’s path to the total path;middle-dose GP-1(40mg/kg) could effectively shorten the escape latency on the3rdand4thday.(3) The result of HE staining show that high-dose GP-1group exhibitimprovement on neuron loss, arranged clutter and morphological features of apoptosisin rats’ hippocampal CA1sub-region when compared with the model group.(4) High-dose GP-1(80mg/kg) can remarkably inhibit the expression ofp-tau-Thr231and NF-κBp65while promote the expression of MAP2. Middle-doseGP-1(40mg/kg) can effectively inhibit the expression of p-tau-Thr231andNF-κBp65.3．Effectiveness study of ginseng polysaccharides fractions on Aβ25-35-inducedAlzheimer’s disease(1) GP-2mainly consisted of two oligosaccharides of which the molecularweight were566Da (38%) and325Da (81%); GP-3mainly consisted of twooligosaccharides of which the molecular weight were670Da (20%) and308Da (50%).The molecular weight of GP-4was distributed at the range of1300Da to40000Da.Glucose was the predominant monosaccharide in the two samples.GP-3and GP-2had higher total carbohydrate contents (57.56%and52.04%,respectively) than GP-4(37.27%) and GP-1(28.37%). The protein contents of GP-4was46.98%.(2) The prolongation of escape latency induced by Aβ25-35was reversedeffectively by GP-1on the3rd and4th day, and by GP-2and GP-3on the2nd and4thday. However, no significant difference was shown in neither the number of crossingsover the platform position nor the ratio of platform quadrant’s path to the total path ofGP-2, GP-3and GP-4when compared with the model group, while significantdifference was shown of GP-1in terms of the two. Conclusion:1. Ginseng glycopeptides could alleviate the scopolamine-induced learning andmemory disorder by reversing the increased activity of AchE.2. The high-dose GP-1(80mg/kg) exerts therapeutic effect on Aβ25-35-inducedAlzheimer’s disease. The probable mechanism might be inhibiting thehyperphosphorylation of tau protein at Thr231epitope; lowering the combination ofMAP2with phosphorylated tau protein to protect the neuron cytoskeleton againstdestruction and inhibiting the cell apoptosis.3. The evaluation of anti-Aβ25-35-induced Alzheimer’s disease activityrevealed that GP-1exerts the most therapeutic effect of the four samples, while GP-2and GP-3exhibit effective-activity of the disease on some level. GP-4shows nothingactivity on anti-Aβ25-35-induced Alzheimer’s disease. It can be indicated from thecomparison that the active ingredient might exist in the dialysate dialyzed (10kD)from GP-1, which deserved further research.