Structural Analysis Of Cantharellus Cibarius Galactan And Its Efficacy In Alleviating Alzheimer’s Disease

The main clinical symptoms of Alzheimer’s disease(AD)are memory decline,cognitive dysfunction,and motor behavior ability.Due to the complex pathogenesis,there is no treatment or drugs that can cure or reverse the disease process radically.Edible fungal polysaccharides have low toxicity and little side effects,and have many biological activities such as neuroprotection and anti-inflammation.However,the high molecular weight of polysaccharides limits the extent to which they are absorbed and utilized by organisms,thus weakening their biological activities.In this project,we extracted a water-soluble α-1,6-galactan from chanterelle,which is then degraded to a smaller poly-saccharide with a molecular weight of 5 k Da(CCP).Its therapeutic effect on APP/PS1 mice was then studied.The specific research contents were as follows:The water-soluble total polysaccharide was extracted from chanterelle by boiling for many times.The neutral and acidic polysaccharides were separated by a DEAE-cellulose column.The neutral polysaccharides with different molecular weights were separated by hollow fiber ultrafiltration column.The monosaccharide composition was analyzed.The galactan with molecular weight of about 20 k Da was degraded to about 5 k Da to increase the solubility,thus facilitating structural analysis and biological utilization.This sample was named CCP.In the monosaccharide methylation analysis,we found that the main structure of CCP is α-1,6-galactan,in which part of 3-C of galactan is replaced by methoxy group.CCP also has a small amount of mannose branches,which can be verified by NMR spectrum.APP/PS1 mouse model was selected to test the neuroprotective activity of CCP at the animal level.After 8 weeks of oral administration,the effect of CCP on spatial memory and non-spatial memory of APP/PS1 mice was explored through Morris water maze,new object recognition,passive and active avoidance,and step-down tests.The study found that after the same training,the learning and memory abilities of APP/PS1 mice of the CCP-treated group were shown to be higher than those of the model group.These results indicated that CCP could improve the memory and cognitive abilities of the AD mice model to a certain extent.After behavioral tests,the brain,liver,spleen and kidney samples of mice were collected.After measuring the organ indexes and carrying H&E staining,no marked pathological differences were observed in the hippocampus,liver,spleen,or kidney,indicating the safety of CCP.Deposition of cerebral amyloid-beta(Aβ)was evaluated through immunohistochemistry.CCP administration could significantly decrease Aβ plaques in the cortex and hippocampus of APP/PS1 mice.Proteomic analysis showed that the neuroprotective effect of CCP was closely related to C3.Immunofluorescence analysis showed that CCP significantly inhibited the activation of microglia and astrocytes and downregulated the expression of C3 and C3 a R.Western blot showed that CCP could regulate the expression of inflammatory factors and nuclear factor(NF)-κB pathway.These results confirmed that CCP could improve AD by inhibiting neuroinflammation,which is related to C3.To sum up,the galactan CCP prepared after extraction,purification and degradation from chanterelle can inhibit Aβ deposition and regulate C3 pathway in the brain of APP/PS1 mice,thus alleviating neuroinflammation.It is confirmed that CCP can improve cognition and memory,thus alleviating AD.This study provides theoretical and experimental evidence support for the promotion and application of edible fungal polysaccharides in the treatment of neurodegenerative diseases.