The Anti-diarrhea Activity Of Sulfated Polysaccharides From Porphyra Haitanensis And Gracilaria Lemaneiformis

Diarrhea is one of the most common human and animal diseases in the world,especially in developing countries.The morbidity and mortality of diarrhea are very high,and it has attracted the great concern of governments and scholars.Previous studies have shown that sulfated polysaccharides derived from marine algae have various biological activities,such as anti-bacteria,anti-inflammatory and immunomodulatory.Exploring the effects of sulfated polysaccharides on bacterial diarrhea and allergic diarrhea can provide new ideas for the prevention and treatment of diarrhea diseases.It can also provide a theoretical basis for the development of anti-diarrhea functional foods or feeds.Through the extraction method of high temperature pressure treatment combined with ethanol precipitation,Porphyra haitanensis sulfated polysaccharide(PHSP_（hp）)and Gracilaria lemaneiformis sulfated polysaccharide(GLSP_（hp）)were isolated from seaweed powder of Porphyra haitanensis and Gracilaria lemaneiformis.The average molecular weight,viscosity,sulfate content of PHSP_（hp）and GLSP_（hp）were 165.45 kDa,0.17 dL/g,10.94%,and 71.87 kDa,0.10 dL/g,11.26%,respectively.Scanning electron microscopy results showed that the microstructure of PHSP_（hp）exhibited an irregular geometrical shape with a certain gap on the surface and loosely superimpose.However,the surface structure of GLSP_（hp）was smooth and flat,showing a continuous sheet.The immunomodulatory activities of PHSP_（hp）and GLSP_（hp）were analyzed by RAW264.7 cells in vitro.The results showed that both PHSP_（hp）and GLSP_（hp）could cause scratch healing and migration of RAW264.7 cells.It could significantly promote the secretion of tumor necrosis factor-α（TNF-α）and interleukin（IL）-6 inflammatory cytokines,and GLSP_（hp）has strong immunomodulatory activity.In this study,PHSP_（hp）and GLSP_（hp）with immunomodulatory activity were used to explore the activity of anti-bacterial diarrhea and anti-allergic diarrhea using a mouse model.In the mouse model of bacterial diarrhea,PHSP_（hp）and GLSP_（hp）could alleviate diarrhea symptoms in mice,significantly reduce diarrhea index,and decrease the level of serum IgA antibody,mast cell protease-1（mMCP-1）and inflammation cytokine TNF-α.Flow cytometry results showed that both PHSP_（hp）and GLSP_（hp）significantly inhibited the proliferation of spleen-derived B cells and promoted the differentiation of regulatory T（Treg）cells compared with diarrhea positive mice.And their microstructure shown that PHSP_（hp）and GLSP_（hp）protect jejunum villi from damage by model bacteria.The anti-allergic activity of PHSP_（hp）and GLSP_（hp）was evaluated and explored by using ovalbumin induced-mouse allergic diarrhea model.Oral PHSP_（hp）and GLSP_（hp）could alleviate diarrhea in mice and protect the jejunum from damage.The results of ELISA showed that PHSP_（hp）and GLSP_（hp）could significantly decrease the levels of specific antibodies,histamine,mMCP-1and Th2 type cytokine IL-4 in allergic mice serum.In addition,the levels of Th1 type cytokine IFN-γand Treg-associated cytokines IL-10 and TGF-βwere increased by treatment with PHSP_（hp）and GLSP_（hp）.Flow cytometry results showed that PHSP_（hp）and GLSP_（hp）inhibited the proliferation of spleen-derived B cells,the differentiation of mast cells and promoted the differentiation of Treg cells compared with allergic positive mice.Furtherly,16S rRNA sequencing showed that PHSP_（hp）and GLSP_（hp）could alleviate allergic reactions in mice by regulating intestinal microflora with increasing the number of Firmicutes and reducing the proportion of Bacteroidetes.In summary,PHSP_（hp）and GLSP_（hp）had anti-diarrhea activity,and the activity of GLSP_（hp）was stronger.However,there were differences in the ways of relieving diarrhea.The present study provideed theoretical basis for the development of functional foods or feeds to the relief of diarrhea diseases.