Study On Anti-aging Effect And Mechanism Of Polysaccharides From Agrocybe Aegerita

Aging is an accumulating process with diverse and harmful changes occurring in cells and tissues as one’s age growing.There are increasing concerns about developing new anti-aging methods from natural dietary supplements.Based on this,it is of greater practical significance for strengthening research on aging mechanism and anti-aging approaches,exploring new ideas and methods of delaying the appearance of aging signs and reducing the incidence of aging-related diseases from the perspective of food science and food nutrition.Researches have shown that fungal polysaccharides have a variety of biological activities,such as improving immunity,antioxidant and anti-aging effects.Agrocybe aegerita is an edible mushroom with rich nutrition and unique aromatic flavor of fungi,which is one of the important and characteristical agricultural products in Fujian Province.In this research,Agroclybe aegerita was used as basic materials to extracting polysaccharides(AAPS),and the anti-aging function and mechanism of AAPS was deeply studied from different levels through vitro experiments,animal experiments,cells experiments and molecules analysis,aiming to provide theoretical basis and technical support for making efficient use of Agrocybe aegerita resources and developing AAPS as anti-aging dietary supplement.The main content and results of this research were as follows:1.The optimum hot-water extraction conditions of AAPS were:extraction temperature 92℃,extraction time 2.5 h,water to material 41.Polysaccharides were precipitated from the fruiting body of Agrocybe aegerita by three different final concentration of ethanol(40%,60%,85%for AAP-1,AAP-2,AAP-3,resperctively).The results showed that AAP-3 polysaccharide had the lowest molecular weight(15866 Da),the highest content of uronic acid(5.16±0.35%)and the highest purity(96.61%).All polysaccharides contained L-rhamnose,fucose,D-arabinose,D-xylose,D-mannose,D-glucose and D-galactose,among which D-glucose,D-galactose and fucose were the three most important monosaccharides.The relative molar percentages were quite different among three polysaccharides.The scavening capacities on DPPH radicals and superoxide anion radicals and the total reducing power of AAP-3 were significantly higher than those of AAP-1 and AAP-2.2.The optimal conditions of MRC-5 premature senescence model were:H2O2 concentration 100 mM,H2O2 treatment time 24h,resveratrol concentration 30 mM,AAPS concentration 0.1mg/ml(low),0.8 mg/ml(middle),2 mg/ml(high).MTT showed that H2O2 could effectively induce MRC-5 cell senescence and decrease the cell proliferation rate,while AAPS and resveratrol could effectively improve the cell viability.H2O2 decreased the content of GSH,while AAPS at middle concentration(0.8 mg/ml)or high concentration(2 mg/ml)improved the GSH content and delayed cell senescence based on strong intracellular antioxidant effect,and AAPS at low concentration(0.1mg/ml)had no obvious effects.H2O2 effectively reduced the telomerase activity and accelerated the cell senescence,while AAPS recovered the telomerase activity to a certain extent,but could not restore it to the no-treatment group.The intervention mechanism of AAPS to cell premature senescence might be that AAPS up-regulated the expression of aging related genes such as Nampt,Prx1,Sirt1,Klotho,turning out to decelerating the cell senescence.3.AAPS effectively ameliorated aging signs of experimental mice,reduced body weight,making it close to the weight in no-treatment group.AAPS decreased the serum levels of ALT,TG and LDL,increased the serum levels of HDL;increased the activity of T-AOC,CAT,GSP-Px and MDA in liver homogenate.The results showed that AAPS could decrease the blood lipids,promote the health of the cardiovascular system,enhance antioxidant capacity,eliminate excessive free radicals,reduce oxidative damage,protect effect to liver cell and organs and defer the organism senescence.4.The number of OTU of mice in AAPS group was higher than that in D-galactose model group.According to the Alpha Diversity Index,the abundance of intestinal flora in D-galactose model group was much lower than that in no-treatment group,which correspondingly reduced the balance of intestinal tract.AAPS,especially that with high concentrations,could increase the intestinal flora richness of D-galactose group induced senescent,even restoring it to the level of no-treatment group.The abundance of Anaerotruncus was relatively stable among all groups.The composition and structure of others flora had changed between model group and tested group.The abundance of some species bacteria such as Lachnospiraceae_NK4A136_group,Bacteroides Bacteroides,Alloprevotella,Helicobacter,Helicobacter unclassified_f_Lachnospiraceae,Roseburia,Parabacteroides were changed by AAP-3 diet intervention.The abundance of Alistipes,uncultured_f_Lachnospiraceae,Rikenella could not be affected by AAPS.The abundance of Norank-f-Bacteroidales_S24-7_group and Desulfovibrio were worsened by AAPS.The composition of the intestinal flora from high AAPS concentration group was close to that from middle concentration group;composition of the intestinal flora from D-galactose model group was close to that from low concentration group.The intestinal community composition could be changed by resveratrol diet intervention.5.Results of transcriptome sequencing of livers showed AAPS could enhance genes expression of functions such as body temperature regulation,carbohydrate biosynthesis,monosaccharide absorption and transformation.The result of KEGG enrichment analysis showed that the differential expression genes were enriched in 189 channels,and five of them were enriched,including peroxisome proliferator-activated receptor signaling pathway,steroid synthesis pathway,arachidonic acid metabolism pathway,unsaturated fatty acid synthesis pathway,and fatty acid degradation pathway.