[HNMP]HSO₄ Catalyzed Synthesis Of Selenized Artemisia Sphaerocephala Polysaccharide And Its Immunomodulatory Effects On RAW264.7 Cells

Recently,selenylation of polysaccharides has been reported as an efficient way to enhance the immunomodulatory activities.However,little is known about the effect of Se content on immunomodulatory activities in selenized derivatives.At present,the Se content of selenized polysaccharides synthesized by traditional selenylation method?HNO₃-Na₂SeO₃?is limited,which is not conducive to the investigations of structure-activity relationships,and environmental unfriendly.Therefore,it has been necessary to develop a new polysaccharide selenylation system with greater effectiveness and higher Se content under mild reaction conditions,which enlightening investigations of structure-activity relationships.Based on this,selenized Artemisia sphaerocephala polysaccharides?SePAS?were synthesized by employing[HNMP]HSO₄ as catalyst under mild reaction conditions in this study.The effects of Se content on immune activity and the mechanism of immune regulation of SePAS were evaluated by cell experiment in vitro.The main research contents and conclusions of this paper were as follows:1.Synthesis of SePAS catalyzed by[HNMP]HSO₄[HNMP]HSO₄ showed excellent catalytic property,which was ascribed to its strong Br?nsted acidity.[HNMP]HSO₄ could enhance the protonation ability of H₂SeO₃resulting in selenized polysaccharides with higher Se contents?SePAS₃ showed maximum Se content of 8744?g/g?which exhibited an approximately 5-fold higher Se content that of SePAS_C without[HNMP]HSO₄?1677?g/g?.FT-IR,XPS,1D/2D NMR exhibited that Se had been successfully introduced into PAS at C-6 substitution,which existed in the form of selenate group(Se⁴⁺).In SEC-MALLS analysis,a decrease in M_W?0.25-5.86×10⁴ g/mol?with narrow molecular distribution was observed which attributed to the acidic hydrolysis caused by[HNMP]HSO₄.2.Effects of SePAS on immunomodulatory activity and its induces activation of MAPKs and NF-?B signaling pathway in vitroSePAS could significantly enhance the immunoregulatory effect of macrophage RAW264.7,and SePAS with high Se content?SePAS₃,8744?g/g?exhibited stronger immunomodulatory activities.It could be concluded that Se content was one of the key factors to enhance the immunomodulatory activities of selenized PAS on macrophage RAW264.7.The mechanism of SePAS immunostimulating assays indicated that SePAS was mainly exerted through up-regulating phosphorylation of various transcription factors?ERK1/2,JNK1/2,p38 and p65?in MAPKs and NF-?B signaling pathways,thereby promoting proliferation,enhancing phagocytic capacity and stimulating the production of NO and cytokines?TNF-?,IL-1?and IL-6?in RAW264.7 cells.In conclusion,SePAS with high Se content is synthesized under mild conditions with[HNMP]HSO₄ as catalyst,and the effects of Se contents in SePAS on the immunoregulation activities of macrophages RAW264.7 cells were compared.Furthermore,the mechanisms of SePAS immunostimulating assays were preliminary investigated in vitro.The present study provided a theoretical basis for the correlation between Se contents and immunomodulatory activity for further exploration.