Study On The Structure,Antioxidantand Intestinal Immunomodulatory Effects Of Acetylated Cyclocarya Paliurus Polysaccharide

Polysaccharides have biological functions such as antibacterial,antiviral and immune system regulation.Relevant studies have shown that moderate acetylation modification of polysaccharides couldsignificantly enhance the antioxidant and immunomodulatory functions of the polysaccharides.In this paper,the structure,antioxidant capacity and intestinal immune regulation of acetylated Cyclocarya paliurus(CPP)polysaccharide was studied,and a scientific theoretical basis was provided for the development of functional foods using Cyclocarya paliurus polysaccharide as raw material.The elution layer was eluted with a DEAE fiber column and the 0.1 M Na Cl elution layer was collected.After freeze-drying,the polysaccharide of Cyclocarya paliurus(CPP_0.1),was obtained.Finally,acetylated Ac-CPP_0.1was obtained by acetylation modification.The in vitro antioxidant activity of CPP_0.1and Ac-CPP_0.1 was evaluated.And established a H₂O₂-induced oxidative stress dendritic cells(DCs)model to evaluate its effect on the antioxidant capacity of DCs.At the same time,the immunomodulatory effects of CPP_0.1and Ac-CPP_0.1 on the intestinal immunity and intestinal microbiota of immunosuppressed mice treated with cyclophosphamide were studied.Combining the results of physicochemical properties and biological activity determinations,the structure,antioxidant capacity and intestinal immune regulation of acetylated Cymbidium vulgare polysaccharides were evaluated.The main results were as follows:1)The physical and chemical properties,molecular weight and monosaccharide composition of CPP polysaccharides were changed after acetylation.The carbohydrate content,uronic acid,protein and molecular mass of CPP_0.1were 94.94±0.42%,2.13±0.08%,1.97±0.07%and 38.4 k Da,respectively.The monosaccharide compositions in CPP_0.1were mainly composed of arabinose,galactose in a molar ratio of 0.473:0.504.The chemical analysis of Ac-CPP_0.1 evaluated that the carbohydrate content,uronic acid,protein,molecular mass and DS of CPP_0.1were 90.82±0.44%,4.91±0.24%,1.83±0.05%,30.7 k Da and 0.18±0.02,respectively.The monosaccharide compositions in Ac-CPP_0.1were mainly composed of arabinose and galactose in a molar ratio of 0.529:0.450.The backbone of Ac-CPP_0.1 was 3)-?-D-Galp-(1?,with some branches?-L-Araf-(1?;?-D-Galp-(1?linked O-6;O-5;O-4,and substituted with acetyl groups at O-2 and O-6position.The NMR spectrum and FT-IR spectroscopy proved that the hydroxy group of CPP polysaccharide was successfully replaced by the acetylation group.Compared with the CPP_0.1,the molecular weight of Ac-CPP_0.1was decreased.The reason may be that the treatment with aggressive acetic anhydride cleaves the polysaccharides.GC-MS results show that the acetylation modification has a certain effect on its monosaccharide composition ratio.2)Acetylation modification significantly enhanced the antioxidant activity of CPP.Acetylation modification significantly improved the scavenging activity of the polysaccharides on ABTS,DPPH free radicalsandferric-reducing power activity.The oxidative stress model of H₂O₂-treated DCs was established.The results showed that CPP_0.1 and Ac-CPP_0.1 significantly increased the activity of SOD,CAT,GSH-Px and T-AOC(P<0.05).At the same time,CPP_0.1 and Ac-CPP_0.1 up-regulated Nrf2,down-regulate the Keap1,enhanced the antioxidant level of dendritic cells,and the antioxidant capacity of Ac-CPP_0.1 was stronger than that of the CPP3)Acetylation modification significantly enhanced the immunomodulatory effect of CPP.The immunosuppressive mouse model was established by cyclophosphamide-treated,Ac-CPP_0.1 significantly restored the thymus index and spleen index of cyclophosphamide-treated mice(P<0.05),and increased the levels of TNF-?,IL-4,IL-17 and TGF-?3 and the m RNA levels of TNF-?,IL-4,IL-17 and TGF-?3 in the small intestine of cyclophosphamide-treatedmice(P<0.05).And Ac-CPP_0.1up-regulated the expression of TRL4,NF-?B,p-NF-?B and p-I?B?in the small intestine of cyclophosphamide-treated mice(P<0.05),and activated the NF-?B signaling pathway.Meanwhile,Ac-CPP_0.1modulated gut microbiota by restoring the relative abundances of Lactobacillus,Bacteroides and Bifidobacterium and decreasing the abundance of Clostridium,Desulfovibrio and Staphylococcus and improving the level of SCFAs in cyclophosphamide-treated mice.These results shown that Ac-CPP_0.1 could be utilized by gut microbes to produce SCFAs,and CPP_0.1 and Ac-CPP_0.1 restored cyclophosphamide-treated gut microbial misadjustment by improving the diversity of microbial community,regulating the structure and composition of microbial community,restoring intestinal microbial imbalance and regulating intestinal microbial ecology.