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Allergy-alleviating Activity And The Mechanism Of Porphyra Haitanensis Polysaccharides From Different Harvesting Periods

Posted on:2023-10-11Degree:MasterType:Thesis
Country:ChinaCandidate:Z Q YeFull Text:PDF
GTID:2531306791467464Subject:Food Science and Engineering
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Porphyra haitanensis is one of the main economical seaweed species cultivated in coastal areas of China.It exhibits significant immunomodulatory,antitumor,and anti-inflammatory activities.Seaweed can be harvested at different growth periods.Polysaccharides are the main functional components of Porphyra,and their chemical structures and biological activities change with different harvest periods.The relationship between the chemical structure and functional activity of Porphyra polysaccharides caused by different harvest periods is still unclear.In recent years,a variety of food-derived seaweed polysaccharides have been found to show significant anti-allergic activities,so identifying the polysaccharides with strong anti-food-allergy activity from Porphyra in different harvest periods would facilitate the prevention of food allergy.In order to determine the differences in the food allergy-alleviating activity of Porphyra polysaccharides from different harvesting periods,based on the different charge and molecular weight,the polysaccharides were separated and purified,obtained three crude polysaccharides,and nine relatively homogeneous polysaccharides were purified based on this.Using intestinal epithelial cells,dendritic cells,T cells,and transwell technology,a three-dimensional intestinal cell model that simulates the intestinal mucosal immune environment was constructed.Allergen OVA was used to induce allergic responses in the three-dimensional cell model and a Balb/c mice model,and various Porphyra polysaccharides were screened to reveal the representative functional polysaccharides,and to explore the mechanism of Porphyra polysaccharide alleviating OVA-mediated allergic responses.Subsequently,the hyperfine structure of polysaccharides was analyzed to explore the relationship between the food allergy alleviating activity and the chemical structure.The main findings of this research are as follows:1.Three kinds of crude polysaccharides(CPHP1,CPHP2 and CPHP3)were extracted from Porphyra haitanensis in different harvest periods.Then the products were further purified through the cellulose DE-52 ion-exchange chromatography column and the Sephadex G-100 gelatin column,Nine polysaccharides(PHP1-1,PHP1-2,PHP1-3,PHP2-1,PHP2-2,PHP2-3,PHP3-1,PHP3-2 and PHP3-3)were separated and purified.The electronegativity,fraction proportion and sulfate radical content of CPHP3 were significantly different from CPHP2 and CPHP3.2.The 12 kinds of purified Porphyra polysaccharides were used to stimulate a three-dimensional intestinal cell model.RT-q PCR and flow cytometry analysis showed that third fraction of crude polysaccharides in each harvest periods suppressed the increased of TSLP,IL-33,OX40 L,IL-6,GATA-3,IL-4,and INF-γ gene expression by OVA stimulation.PHP3-3 significantly suppressed the Th0 cells differentiation to Th2 and Th1 cells induced by OVA.The anti-allergic ability of the fractions gradually increased according to the eluent order of DE-52,and the polysaccharide with the strongest,the moderate and the weakest activity was PHP3-3,PHP2-3 and PHP1-1.3.When treated influence OVA-mediated allergic mice by the polysaccharides,the clinical symptom score was reduced,the OVA-specific Ig E,histamine and cytokine IL-4 in serum were significantly decreased,and the contents of Ig G2 a and INF-γ were increased.The expression of pro-inflammatory factors IL-33,IL-6,IL-4,and GATA-3 were significantly decreased in the spleen,large intestine and small intestine.Among them,CPHP3 significantly reduced the expression of related allergic genes,suppressed OVA-induced Th0 cells differentiate to Th2 cells,reduced intestinal injury,and alleviated the allergic reaction mediated by OVA.The ability of the polysaccharides to alleviate OVA-mediated allergy was CPHP1<CPHP2<CPHP3.4.The physicochemical characterization analysis found that the monosaccharide composed of Porphyra polysaccharides were mainly galactose and 3,6-lactone galactose,and the content of other monosaccharides was limited.3,6-lactone galactose may exist mainly inβ-type.PHP2-3 and PHP3-3 both contain α-and β-glycosides,and PHP1-1 may only haveα-glycosides.The molecular weights of the characteristic polysaccharides PHP1-1,PHP2-3and PHP3-3 were 13.73,366.87 and 609.85 k Da,respectively.The 4-O-linked 6-sulfateα-L-galactose content was PHP1-1<PHP2-3<PHP3-3,the 3,6-anhydro-α-L-galactose content was PHP1-1>PHP2-3>PHP3-3.Moreover,the number of glycosidic bond types PHP1-1>PHP2-3>PHP3-3.5.The food allergy alleviating activity of Porphyra polysaccharide was positively correlated with the content of sulfate radical,4-O-linked 6-sulfate α-L-galactose,and the molecular weight,and negatively correlated with the content of glucuronic acid,3,6-lactone-α-L-galactose and number of glycosidic bond types.It is suggested that these groups and compositions are related to the anti-allergic activity of polysaccharides.
Keywords/Search Tags:Porphyra polysaccharide, harvest periods, anti-food allergy, intestinal three-dimensional cell model, structure-activity relationship
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