Comparison of Structure and Immune Activity of Dioscorea opposita Thunb.Polysaccharides before and after Starch Removal

ZHANG Chuanxiang; DING Jie; LIU Xin; WANG Di; LIU Qian; SHANG Guichun; LIU Yuhong

doi:10.13982/j.mfst.1673-9078.2026.1.1593

Abstract：The effect of starch removal treatment on the molecular weight,monosaccharide composition,functional groups,and in vitro immune activity of Dioscorea opposita Thunb.polysaccharides(DOP)was investigated.Polysaccharides were extracted using aqueous alcoholic precipitation.Specifically,the aqueous extract was directly precipitated with alcohol to obtain Dioscorea opposita Thunb.starch-containing polysaccharides(WDRP)and treated with α-amylase followed by alcoholic precipitation to obtain Dioscorea opposita Thunb.non-starch polysaccharides(CDRP).Chromatography and spectroscopy were combined to compare the structural information of the polysaccharides before and after starch removal.The molecular of WDRP has one more 1 590 kDa weight peak for starch than CDRP.In addition,while WDRP and CDRP had the same monosaccharides,there were notable differences in the molar percentages of specific monosaccharides.The molar percentage of glucose in WDRP was 20.93%lower than that in CDRP,while the percentage of other monosaccharides was greater than in CDRP.A cell assay revealed that the cell viability in the WDRP group reached 188.50%,while that in the CDRP group was 166.69%.Additionally,the phagocytosis rate was significantly higher in the WDRP group than in the CDRP group.Further analysis revealed that WDRP and CDRP play an immunomodulatory role by activating the p38 MAPK/NF-κB pathway to regulate the secretion of NO,TNF-α,IL-6,and IL-1β.In addition,the p38 MAPK and NF-κB protein expression levels were higher in WDRP than in CDRP,suggesting that WDRP exhibits stronger in vitro immunoactivity than CDRP.The findings indicated that the removal of starch from yams leads to varying structures of polysaccharides,which in turn result in differences in their activities.This suggested that amylase may disrupt the deconstruction of non-starch polysaccharides,thereby reducing their activity.These findings provide a reference for subsequent studies on the isolation and purification of DOP.