| Intestinal tract is one of the largest immune organs in human body,and the intestinal barrier dysfunction can easily lead to food allergy.Therefore,it may be an effective strategy to prevent and treat food allergy to regulate the balance of intestinal microecology.Cyanidin-3-O-glucoside(C3G)is the most widespread anthocyanin in nature,whichhas many physiological activities such as anti-inflammatory and regulating intestinal flora.However,there are few reports about anthocyanins to improve food allergies by regulating the intestinal tract.In view of the poor sta-bility and low bioabsorption of anthocyanins,the sodium alginate-C3G self-assembled particles were prepared used by enteric sodium alginate to explore its intestinal absorption effect and an-ti-food allergy mechanism.The main results are as follows:1.The preparation of low viscosity sodium alginate and sodium alginate-C3G self-assembled particles.The low viscosity sodium alginate(LVA)with 2.98 mpa·s viscosity,-34.4 m V zeta potential and good enteric solubility was obtained by high temperature and high pressure treatment.The optimal conditions for LVA and C3G self-assembled particles are:LVA/C3G mass ratio 3:1,p H 3.0,reaction time 60 min,temperature 4°C protected at dark,and the C3G binding rate reached 84.24%.Scanning electron microscopy observation revealed that the LVA-C3G complex was a porous network structure;infrared spectroscopy analysis showed that the self-assembled particles removed the characteristic peaks of C3G at 1638 cm-1 and 1443cm-1,and the characteristic peaks at 1614 cm-1 and 1417 cm-1 of COO-of LVA were moved to1617 cm-1 and 1422 cm-1,respectively;the differential thermal scan showed that the endothermic peak shifted from 231°C to 223°C after the self-assembly of LVA and C3G.The molecular docking software simulates the optimal configuration of LVA and C3G,which further confirms that the hydroxyl hydrogen of C3G is combined with the COO-group of LVA through hydrogen bonding.2.The storage stability and intestinal absorption of LVA-C3G self-assembled particles.Compared with unembedded anthocyanins,the self-assembled particles stored at 25°C for 35days,the preservation rate increased by 15.53%.The results of simulated gastrointestinal diges-tion in vitro showed that the C3G was stable in simulated gastric fluidat p H 2.0,but it is easy to degrade in simulated intestinal fluid at p H 7.4,with retention rate was only 46.25%;however,the retention rate of C3G embedding with LVA was nearly 70.00%after simulated gastrointesti-nal digestion,the bioavailability was increased by 23.22%,and the antioxidant capacity was in-creased by 10.21%.After 4 weeks of intragastric administration of mice,the serum response value of C3G was increased by 27.40%,the serum concentration was up to 22.92 nmol/m L,and the content of C3G in feces was decreased by 30.65%.3.The effect of LVA-C3G self-assembled particles on the intestinal microecology of nor-mal mice.The C3G and LVA-C3G complexes were administered to mice at a dose of 25.00mg/kg·day(C3G equivalent)for 4 weeks.Compared with the blank group,the mouse thymus index increased significantly(P<0.05).As for the intestinal physical barrier,the C3G can effec-tively promote the growth of intestinal villi before and after embedding,but the LVA-C3G can promote the secretion of intestinal mucus more significantly;compared with blank group,the serum D-lactic acid level of LVA-C3G mice decrease by 23.89%(C3G is 9.65%),the?-defensin and mucin-2 levels increased by 14.64%(C3G is 5.80%)and 13.89%(C3G is 9.30%),respec-tively;The three tight junction proteins of intestinal epithelium Claudin-1,Occludin and ZO-1increased by 24.71%(C3G for 15.17%),21.66%(C3G for 13.41%),and 21.31%(C3G for7.75%),respectively.In terms of intestinal immune barrier,the C3G and LVA-C3G can signifi-cantly(P<0.05)increase the expression levels of s Ig A,TNF-?,INF-?,IL-4,IL-10 and IL-18,and is more effective in s Ig A,INF-?,IL-4,IL-10 and IL-18 expression of LVA-C3G.In terms of regulating the intestinal flora,both C3G and LVA-C3G can effectively promote the proliferation of intestinal probiotics,but the LVA-C3G has a better inhibitory effect on intestinal pathogenic bacteria,and the relative abundances of Helicobacter and Turicibacter are reduced by 8.32%and2.79%,respectively.4.The inhibitory effect of LVA-C3G self-assembled particles on food allergy in mice.A food allergy model was constructed by intraperitoneal injection and oral gavage ovalbumin(OVA).It was found that the mouse specific Ig E,Histamine,m MCP-1 and Na+-K+-ATPase ac-tivities were 3835.53 ng/ml and 1141.52 ng/ml,1202.40 pg/ml,5.68?mol Pi/mg prot/h,respec-tively,the body temperature of mice wad decreased,the fecal loose with higher water content,the small intestine villi was damage,and the intestinal wall became thin,the intestinal tight junc-tion protein expression decreased and the microbial composition was changed significantly.Af-ter treatment with C3G,LVA-C3G physical mixture and LVA-C3G self-assembled particles,allergic symptoms such as diarrhea and scratching ears of sensitized mice can be significantly relieved,showing a good anti-allergic effect.In particular,the OVA-specific Ig E,Histamine and m MCP-1 levels of mice in the LVA-C3G self-assembled particles group decreased to 2087.60ng/ml,460.87 ng/ml,and 630.83 pg/ml,respectively,while the activity of Na+-K+-ATPase was increased to 8.41?mol Pi/mg prot/h.In addition,the Th1 type cytokine IFN-?in the intestines increased,while the Th2 type cytokine IL-4 decreased,and these reached a new balance;the lev-el of IL-10,IL-18,IL-22,s Ig A,tight junction protein and antimicrobial peptides(AMPs)has in-creased significantly.From the perspective of intestinal flora,compared with the model group of mice,the abundance of pathogenic bacteria in the LVA-C3G self-assembled particle group,such as Helicobacter and Turicibacter,was reduced by 21.83%and 1.64%,respectively.The abun-dance of beneficial bacteria such as Lactobacillus,Alistipes,Bacteroides and Odoribacter in-creased by 17.69%,5.95%,3.54%and 4.78%,respectively. |
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