| Polygonatum cyrtonema Hua.,an edible and medicinal Chinese medicinal herb,has been currently planted under forests in many regions of China.Polygonatum sibiricum polysaccharides,as the most important component in Polygonatum sibiricum,has always been an important index for the pharmacopoeia to evaluate the quality of Polygonatum sibiricum However,the structural characteristics and pharmacological activities of Polygonatum sibiricum polysaccharides from different varieties and places of origin will also vary.In this paper,the polysaccharides of Polyonatum cyrtonema Hua.cultivated artificially in Ninghua County,Sanming City,Fujian Province were studied.The polysaccharides were extracted,isolated,purified,and structure characterization.The regulatory effects of two kinds of Polyonatum cyrtonema Hua.polysaccharides on gut microbiota were studied.The main results in this paper are as follows:1.The extraction conditions of Polyonatum cyrtonema Hua.polysaccharides were determined as follows:solid-liquid ratio 1:25(g/mL),the extraction temperature 80℃,and the extraction time 2 h.At this time,the extraction yield was 49.21%.PCP 20,PCP 40,PCP 60,PCP 85 and PCP 95 were isolated from the extract of Polyonatum cyrtonema Hua.by the method of graded alcohol precipitation.PCP 85 and PCP 95 were the main components of Polyonatum cyrtonema Hua.polysaccharides,and the yield of crude polysaccharides was 31.35%and 13.68%,respectively.The average molecular weight of PCP 85 and PCP 95 were 1.13～3.06×103 Da and 6.94×102～1.57×103 Da,and the monosaccharides were composed of glucose and fructose,respectively.2.The structure of two homogeneous Polyonatum cyrtonema Hua.polysaccharides PCP 85-1-1 and PCP 95-1-1 separated by ion exchange chromatography and gel column chromatography was analyzed.The molecular weights of PCP 85-1-1 and PCP 95-1-1 were determined to be 4258 Da and 2309 Da,respectively.Scanning electron microscope analysis showed that PCP 85-1-1 was a fragment of polysaccharide with irregular spatial structure,and its surface structure was smooth and slightly fragmented.PCP 95-1-1 was irregularly arranged and loose,and its surface structure was smooth without debris.The methylation,IR spectrum analysis and NMR spectrum analysis showed that PCP 85-1-1 was composed of β-Fruf-(2→,→6)-β-Fruf-(2→,→1)-β-Fruf-(2→,→6)-α-Glcp-(1→,→1,6)-β-Fruf-(2→sugar residue,its sugar residue molar ratio was 1:0.64:2.02:0.21:0.72.Its structural unit is:PCP 95-1-1 was composed of β-Fruf-(2→,→6)-β-Fruf-(2→,→)-β-Fruf-(2→,→6)-αGlcp-(1→,→1,6)-β-Fruf-(2→sugar residues,its sugar residue molar ratio was 1:0.51:3.01:0.39:0.91.Its structural unit is:3.Polyonatum cyrtonema Hua.polysaccharides had a certain anti-digestion ability,indicating that Polyonatum cyrtonema Hua.polysaccharides can as a prebiotic and be fermented by gut microbiota,and improve the acidic environment.PCP 85-1-1 and PCP 95-1-1 can promote the production of acetic acid and propionic acid,and also increase the total content of SCFAs,which is 5.28 times and 4.61 times higher than that of the blank group,indicating that Polyonatum cyrtonema Hua.polysaccharide reduce the pH of the fermentation system in vitro fermentation.4.Polyonatum cyrtonema Hua.polysaccharides have the function of regulating the composition of intestinal microbiota.PCP 85-1-1 and PCP 95-1-1 can reduce the relative abundance of Proteobacteria,while the relative abundance of Firmicutes and Actinobaciota to increase at the phylum level,and significantly increase the relative abundance of the beneficial bacteria Megamonosa and Bifidobacterium in the intestine,and inhibit the content of pathogenic bacteria unclassified_f_Enterchacteriacese,Escherichia Shigella,Klebsiella and Enterobacter at the genus level.The regulatory effect of PCP 95-1-1 was similar to that of inulin,and its regulatory effect was better than that of PCP 85-1-1.In conclusion,the polysaccharides of Polyonatum cyrtonema Hua.cultivated in Ninghua County,Sanming City,and Fujian Province were mainly composed of fructans,and their glycosidic bond composition was consistent with previous reports.However,the molecular weight and monosaccharide composition differed due to differences in origin and varieties.It was a similar effect to the standard prebiotic inulin on regulating intestinal flora.PCP 95-1-1 had a more significant regulatory effect on the intestinal flora.The results of the study deepened the understanding of the polysaccharides from artificially cultivated Polyonatum cyrtonema Hua.in Ninghua County,Sanming City,Fujian Province.They provide a reference for the development of artificially cultivated Polyonatum cyrtonema Hua.. |
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