Pharmacological Basis For Use Of Armillaria Mellea Polysaccharides In Alzheimer’s Disease: Anti-apoptosis And Anti-oxidation

The pathogenesis of neurodegenerative disease is complex and harmful to the body as one of the factors that seriously threatens the health of the elderly.Alzheimer’s disease（AD）,which is caused by the loss of neuron and the degeneration of synapse,is consider as one of the neurodegenerative disease.The pathogenesis of AD remains unknown and there are limited therapeutic drugs.In clinics,its disorders are characterized by the decline of cognitive function and learning.The incidence of AD is increasing in the world and no cure is available until now.It needs to develop high-efficiency and low-toxic AD drugs for prevention and treatment.As functional foods and medicines,fungi exhibit various pharmacological activity with few side effects.Armillaria mellea,an edible mushroom,has been found and used in East Asia for hundreds of years.In traditional medicine,the hazel fungus has been reported to show various pharmacological effects,including retarding aging,hypnosis,calmness,and improving immunity.As the main component of Armillaria mellea,polysaccharide exhibits the antioxidant activity through scavenging the superoxide radical.However,the potential beneficial effects of Armillaria mellea on neurodegenerative diseases,particularly AD have not been reported yet.In this paper,the neuroprotective activity of Armillaria mellea in Alzheimer’s disease and its primary mechanism were studied via the anti-oxidative and anti-apoptotic pathways.The main contents of this research include the following parts:1.Preparation of Armillaria mellea polysaccharidesIn this study,a series of crude polysaccharides with different concentrations of ethanol were obtained by hot water extraction,sevag reagent,dialysis and gravimetric alcohol precipitation,named as AMPSa-e.The production of polysaccharides in Armillaria mellea mycelium was 0.93%,1.30%,1.93%1.60%,1.00%.In the present study,the neuroprotective effects of Armillaria mellea mycelium polysaccharides（AMPS）were investigated in L-Glu-induced HT22 apoptotic cells and D-gal plus AlCl₃-induced AD mice.2.Study on nuroprotective activity of AMPSc and its mechanism in vitroIn the L-Glu-induced HT22 cell apoptosis model,the viability of HT22 cell was detected by MTT assay,DCFH-DA fluorescence staining was used to detect the intracellular ROS accumulation,the mitochondrial membrane potential（MMP）and the proportion of the apoptotic cells were measured by flow cytometry,and the activities of caspase-3 were analyzed through commercial kits.The results showed that AMPSc strongly improved cell viability,prevented the proportion of nuclear apoptosis,suppressed the over-production of intracellular reactive oxygen species,inhibited the activation of caspase-3 and restored MMP.3.Study on nuroprotective activity of AMPSc and its mechanism in vivoIn AlCl₃ plus D-gal-induced AD mouse model,behavioral,physiological and biochemical tests were determined after 8 weeks of modeling and 4 weeks of treatment.The results exhibited that AMPSc significantly enhanced horizontal movements,increased endurance times in rotarod test and reduced escape latency time in Morris water maze test.AMPSc improved the central cholinergic system functions in AD mice indicated by its enhancing acetylcholine（Ach）and choline acetyltransferase（ChAT）concentration,decreasing acetylcholine esterase（AchE）levels in serum and hypothalamus.In addition,AMPSc not only increased the activity of antioxidant enzymes superoxide dismutase（SOD）and glutathione peroxidase（GSH-Px）in the serum and hypothalamus of AD mice,but also inhibited the level of reactive oxygen species（ROS）in the hypothalamus of AD mice and improved the oxidative stress in AD mice status.Moreover,AMPSc alleviated the apoptosis rate,deposition of amyloid beta（Aβ）in the brain regions,oxidative damage and aggregations of p-Tau in the hippocampus of AD mouse.In summary,both in vitro and in vivo experiments demonstrated the neuroprotective activity of AMPS on Alzheimer’s disease via the antioxidant and anti-apoptotic pathways.In this study,our data provide pharmacological evidence that AMPS may serve as a neuro-protective candidate for preventing or treating neurodegenerative diseases.