Study On Alleviating Effect And Mechanism Of Locust Bean Gum Oligosaccharides And Tamarind Seed Polysaccharide Oligosaccharides On Ulcerative Colitis

Ulcerative colitis(UC)is an inflammatory condition of the colon caused by environmental,autoimmune,and dietary factors.Its incidence continues to increase worldwide and has become an important global public health challenge.Current clinical drugs for the treatment of UC,such as 5-aminosalicylates,have shown some therapeutic efficacy,but can also have adverse effects on patients.In recent years,natural plant oligosaccharides have shown better anti-inflammatory activity and have attracted attention.locust bean gum(LBG)and tamarind seed polysaccharide(TSP)are often used as thickening agents in the food industry.However,both of them form colloidal liquid with large viscosity in water,which is not conducive to digestion and absorption in the animal body.This creates difficulties for further development of LBG and TSP.In this study,locust bean gum oligosaccharides(LBGO)and tamarind seed polysaccharide oligosaccharides(TSPO)with lower viscosity and molecular weight were obtained by hydrolysis of trifluoroacetic acid.After separation and characterization,the alleviative effects and mechanisms of action of LBGO and TSPO on ulcerative colitis were investigated.The specific study contents and results are as follows:(1)Preparation and structural characterization of oligosaccharides: The optimal degradation conditions for LBG were obtained: substrate concentration of 5 g/L,TFA concentration of 0.3 M,acid digestion temperature of 80℃,and acid digestion time of 2h.The optimal degradation conditions for TSP were obtained: substrate concentration of5 g/L,TFA concentration of 0.4 M,acid digestion temperature of 90℃,and acid digestion time of 2 h.The crude oligosaccharides of LBG and TSP obtained after removing trifluoroacetic acid were separated and purified by DEAE Sepharose G25 column chromatography to obtain LBGO and TSPO.The yield rates were 62.3% and 56%,respectively.The results of UV spectral showed that the oligosaccharides did not contain impurities such as proteins.Fourier infrared transform spectroscopy and HPLC-ESI/MS showed that both LBGO and TSPO contained pyrans linked by β-glycosidic bonds,and contained some monosaccharides and oligosaccharides with the polymerization degree of2-7.(2)Alleviative effect of oligosaccharides in UC mice: In this experiment,2.5% DSS solution was used to induce the establishment of UC mouse model,and high-dose(4g/kg/day)and low-dose(2g/kg/day)LBGO and TSPO were used to gavage UC mice for 7 days,while Chang Yan Ning(2g/kg/day)was used as a positive control to investigate the alleviating effect of oligosaccharides on UC mice.The results showed that: Compared with the DSS group,LBGO and TSPO administration increased body weight and decreased DAI scores,and the H&E staining results showed that mice with colitis symptoms were reduced,and the differences were statistically significant;ELISA results showed that LBGO and TSPO significantly reduced the levels of pro-inflammatory factors IL-6 IL-1β and TNF-α,indicating that oligosaccharides could significantly alleviate intestinal inflammation in UC mice;RT-qPCR results showed that LBGO and TSPO significantly increased the relative mRNA expression of ZO-1 and Occludin in colon tissues,indicating that oligosaccharides reduced intestinal permeability in UC mice;The result of Western blot showed that LBGO at high dose and TSPO at low dose decreased the expression of NF-κB(p65)protein in colon tissues,indicating that oligosaccharides may alleviate intestinal inflammation in UC mice by regulating NF-κB signaling pathway.(3)Effect of oligosaccharides on intestinal microorganisms in UC mice: The first GC-MS was used to detect the content of SCFAs in colon contents,and the results showed that LBGO and TSPO were able to increase the content of acetic and propionic acids.The structural composition of the intestinal microbiota of mice was analyzed according to 16 S rRNA gene sequencing,regulate the composition and structure of intestinal microorganisms,and bring the structure of flora closer to NOR group.LBGO increased the relative abundance of beneficial gut bacteria such as Blautia,Lactobacillus,and Prevotella.TSPO elevated the relative abundance of Akkermansia,Blautia and inhibited the growth of Turicibacter.(4)Functional prediction analysis showed that DSS intervention altered the abundance of functional genes related to basal metabolism,such as valine,leucine and isoleucine biosynthesis,in the normal mouse intestinal flora.High doses of LBGO reversed this state and bring it closer to normal mice.In this study,LBGO and TSPO were first obtained by acid digestion,and their compositions were initially analyzed.On this basis,the alleviating effects of LBGO and TSPO on DSS-induced UC mice were initially investigated and their mechanisms of action were studied.The results showed that LBGO and TSPO could suppress intestinal inflammation and colonic injury in UC mice,by reducing the levels of pro-inflammatory factors IL-6,IL-1β and TNF-α,increasing the relative mRNA expression of ZO-1 and Occludin,inhibiting the activation of NF-κB signaling pathway and regulating the composition of intestinal flora.These results provide a theoretical basis and reference for the future treatment of UC.