| Sea cucumber is rich in protein,polysaccharide,fatty acid,vitamin B,essential amino acid and other biological active substances and its nutritional health value has been widely recognized.The development of deep processing of the body wall of sea cucumber has produced a large amount of visceral waste.Studies have shown that nutrients in the visceral of sea cucumber are similar to those in the body wall.In this paper,taking sea cucumber tendon,a part of viscera,as the research object,the crude polysaccharide of sea cucumber tendon(SCTP)has been extracted and isolated,while SCTPⅡ has been purified.Moreover,the structure and physical and chemical properties of the polysaccharide of sea cucumber tendon and the immune activity has been investigated.The optimal of extraction process was obtained through single factor experiment and response surface experiment.The results were as follows:extraction temperature was 80℃,material-water ratio was 1:12,extraction times were 3,with each time extracting 3 h.Under these conditions,the extraction yield was 6.05%±0.16%.SCTP was obtained by Sevag method after protein removal.SCTPⅡ was separated and purified by DEAE cellulose-52 ion exchange column.The purity of SCTPⅡ was analyzed by HPLC,its molecular structure was analyzed by gas chromatography,Fourier transform infrared spectroscopy,nuclear magnetic resonance spectroscopy,scanning electron microscopy and atomic force microscopy,and its thermal properties were analyzed by thermogravimetric analyzer and differential calorimetry scanner.The average molecular weight of SCTPⅡ was 5.20×10~3 kDa and the Mw/Mn was 1.05.The total sugar,uronic acid and protein contents of SCTPⅡ were about 82.05%,2.15%and 4.91%,indicating that SCTPⅡ was proteoglycan.SCTPⅡ was composed of glucose and fucose with the molar percentage of 92.09%and 7.91%.The monosaccharide residues were mainlyα-pyran type and mainly consisted of→4)α-D-Glcp-(1→.Scanning electron microscopy of showed that the surface of SCTPⅡ was a thin sheet with smooth edges,which was connected by fine wires to form a complex network structure.Atomic force microscopy showed that SCTPⅡ formed spherical aggregates with uneven sizes,which was related to the triple helix structure.According to TG and DSC analysis,the disintegration temperature of SCTPⅡ structure was 316.04℃,Tp was 73.41℃,ΔH was 1.01 kJ/g,indicating that SCTPⅡ had good thermal stability.To explore the effect of sea cucumber tendon polysaccharide(SCTP)on immune activity,the immunosuppressive mice model was established by cyclophosphamide induction.The results showed that SCTP intervention could alleviate(p>0.05)organ atrophy and restore the liver and spleen tissues of immunocompromised mice to normal morphology with intact cells and tight arrangement,indicating that SCTP has protective effect on the liver and spleen of mice.Compared with model group,the proliferation T cells and B cells in splenic lymphocytes of mice in high dose SCTP group were significantly(p<0.05)and extremely significant(p<0.01)improved,respectively.Each dose of SCTP could improve the proliferation ability of macrophages,and medium dose and high dose of SCTP significantly(p<0.01)increased macrophage phagocytosis,indicating that SCTP could enhance the immune activity of peritoneal macrophages in immunocompromised mice.Cyclophosphamide significantly(p<0.01)decreased the contents of IL-6,TNF-αand IFN-γin serum of immunosuppressed mice,and medium dose and high dose of SCTP could significantly(p<0.01)promote the expression of IL-6,TNF-αand IFN-γin immunosuppressed mice.In addition,SCTP could increase the abundance of Lactobacillus,Akkermansia and other beneficial bacteria in the intestinal tract,while reduce the abundance of Proteus,Alistipes and other harmful bacteria.It was speculated that SCTP could enhance the immune capacity of mice by regulating the intestinal bacteria of mice. |
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