Antidiabetic Effect Of Glucomannan And Its Potential Mechanism Exploration

Diabetes is a kind of metabolic disease characterized by chronic hyperglycemia,which is generally caused by the deficiency of insulin secretion and/or the decrease of insulin sensitivity.Type ? diabetes is a worldwide epidemic and threaten the human health severely.Polysaccharide has been reported to have beneficial effects on type ?diabetes.Glucomannan is a kind of polysaccharides with simple chemical structure,and plants of Dendrobium officinale,konjac and Aloe vera leaves are main sources of glucomannans.Glucomannan is mainly consists of glucose and mannose,whereas the detailed structure of glucomannan from Dendrobium officinale,konjac and Aloe vera including molecular weight,ratio of mannose to glucose,acetyl substituent position and degree of acetyl substituent are different.Based on the previous studies on structure of glucomannans,this study was performed to compare the improvement effects of the three glucomannans and investigate the anti-diabetic mechanisms of konjac glucomannans on type ? diabetes via biochemistry,pathology,metabolomics,lipidomics,proteomics and 16S rRNA sequencing technology.Main contents and results were list as follows:?1?Rats fed on high-fat diet?HFD?were injected with streptozotocin?STZ?into the tail vein to induce type ? diabetes.Then rats were divided into normal control group?NC?,untreated diabetic group?Model?,metformin-treated group?Met?,Dendrobium officinale glucomannan-treated group?DOP?,konjac glucomannan-treated group?KGM?,Aloe gel glucomannan-treated group?AGP?,all the rats were treated with saline/metformin/glucomannans for four weeks.Results showed that glucomannans treatment ameliorated the symptoms of polydipsia,polyphagia and weight loss in diabetic rats.Glucomannans treatment enhanced the glucose tolerance,as well as decreased the levels of blood glucose,glycosylated serum protein and insulin in serum,increased the insulin sensitive.Glucomannans also ameliorated diabetes-induced hyperlipidemia symptom via decreased the levels of total cholesterol,total triglycerides,low density lipoprotein cholesterol and increased the level of high density lipoprotein cholesterol.Furthermore,glucomannans treatment could also improve the function of ? cells,reduce the proliferation of fat cells,relieve the symptoms of glycoprotein deposition in fatty tissues.Compared the three kinds of glucomannans,KGM may be more superior to DOP and AGP in hypoglycemic and hypolipidemic effects.Pearson correlation analysis between clinically relevant indicator of diabetes and structure information showed that molecular weight was positively correlated with hypoglycemic and hypolipidemic activities,ratio of mannose/glucose showed the opposite trend,degree of acetyl substitution has no significantly correlation with hypoglycemic and hypolipidemic activities but was detrimental for the improvement of glucose tolerance.?2?UPLC-triple-TOF/MS based metabolomics and lipidomics were adopt to investigate the effects of glucomannans treatment on serum metabolism of diabetic rats.Results showed that the clusters including carnitine,indoles,cholic acids,saccharides,amino acids,purine,pyrimidine,fatty acyls,glycerolipids,glycerophospholipids,sphingolipids and sterol lipids were significantly changed in diabetic rats.And the significantly changed clusters were mainly involved in phenylalanine,tyrosine and tryptophan biosynthesis,biosynthesis of valine,leucine and isoleucine,metabolism of valine,aspartic acid and glutamate,metabolism of taurine and hypotaurine,phenylalnine metabolism,pentose and glucuromate interconversions,histidine metabolism,retinol metabolism and lipid metabolism.Compared with normal rats,relative abundance of cholic acids,carnitine,monosaccharides,disaccharides,amino acids,fatty acyls,glycerolipids,glycerophospholipids,sphingolipids and sterol lipids were increased in the diabetic rats.Glucomannans treatment decreased the relative abundance of amino acids,saccharides,carnitine,cholic acids,indoles,purine,pyrimidine,as well as significantly decreased the relative abundance of fatty acyls,glycerophospholipids,sphingolipids and sterol lipids,ameliorated the serum lipid metabolism.There is no significantly difference among the three kinds of glucomannans on improvement of serum metabolism.?3?Biochemistry,pathology,metabolomics,and proteomics technologies were adopt to investigate the the liver protection of the three kinds of glucomannans.Results showed that glucomannans treatment decreased the levels of alanine transaminase and glutamic oxalacetic transaminase in serum,increased the liver anti-oxidant capacity,alleviated the liver pathological injury.Metabolomics analysis results showed that the significant changed clusters were carnitine,cholic acid,saturated and unsaturated fatty acid,glycerolipid,saccharides,amino acid,purine,pyrimidine.Relative abundance of cholic acid,carnitine,saccharides,glycerolipid and amio acids in diabetic rats were higher than that of normal rats.Besides,the significantly changed metabolites were mainly involved in liver phenylalanine,tyrosine and tryptophan biosynthesis,biosynthesis of valine,leucine and isoleucine,metabolism of valine,aspartic acid and glutamate,metabolism of taurine and hypotaurine,phenylalnine metabolism,pentose and glucuromate interconversions,histidine metabolism,retinol metabolism,lipid metabolism and galactose metabolism.On the other hand,significantly changed proteins were mainly enriched in liver amino acids,tricarboxylic acid cycle?TCA cycle?,primary bile acids biosynthesis,fatty acids metabolism pathways.In addition,the secretion of proteins enriched in TCA cycle,branched chain amino acids metabolism,primary bile acids biosynthesis and fatty acids metabolism pathways were showed an increased tend,but glucomannans treatment could regulate the disorders of proteins secretion.?4?Effects of glucomannans treatment on intestinal flora regulation was investigated based on 16S rRNA sequencing technology.Results showed the intestinal flora of diabetic rats was disordered.At phylum level,Actinobacteria,Bacteroidetes,Elusimicrobia,Firmicutes,Proteobacteria,Spirochaetes and Verrucomicrobia were significantly different between diabetic and normal rats.KGM and DOP treatment significantly decreased the relative abundance of Actinobacteria,Bacteroidetes,Elusimicrobia,Proteobacteria,and Spirochaetes in diabetic rats.At genus level,Lachnospiraceae_NC2004_group,Prevotella₉,Prevotellaceae_Gaa6A1_group,Citrobacter,Enterococcus,Faecalibaculum were significantly changed between diabetic and normal rats.Glucomannans treatment decreased the relative abundance of Citrobacter,Enterococcus,Faecalibaculum,and increased the relative abundance Lachnospiraceae NC2004_group,Prevotella₉,Prevotellaceae-Ga6A1_group.Compared the three kinds of glucomannans,KGM treatment was superior to DOP and AGP in intestinal flora regulation.?5?Biochemistry,pathology,metabolomics,and 16S rRNA sequencing technologies were combined to investigate the anti-diabetes effects of different dose konjac glucomannan?KGM?and its potential mechanisms.After type II diabetes model was successfully established,rats were divided into normal control group?NC?,polysaccharides control group?PC?,untreated diabetic group?Model?,metformin-treated group?Met?;40,80 and 160 mg/kg KGM treatment groups?KGM-40,KGM-80,KGM-160?,all the rats were treated with saline/metformin/KGM for four weeks.Results showed that KGM treatment ameliorated the symptoms of polydipsia,polyphagia and weight loss in diabetic rats.KGM treatment enhanced the glucose tolerance,improved the hyperglycemia and hyperlipidemia symptoms in diabetic rats.Furthermore,KGM treatment could also improve the function of ? cells,reduce the proliferation of fat cells,relieve the symptoms of glycoprotein deposition,alleviate the symptoms of nonalcoholic fatty liver,lighten the mcosal damage of diabetic rats.Metabolomics analysis showed that KGM treatment improved the cholic acid,saccharide,carnitine and lipid metabolism in liver.16S rRNA sequencing results showed that KGM treatment improved intestinal flora disorders in diabetic rats.At phylum level,KGM treatment decreased the relative abundance of Actinobacteria,Proteobacteria,Deferribacteres and Spirochaetes,increased the relative abundance of Tenericutes and TM 7 in diabetic rats.At genus level,KGM treatment could decrease the relative abundance of Blautia,Dorea,Turicibacter,Bifidobacterium and increase the relative abundance of Lactobacillus in diabetic rats.Correlation analysis between serum lipids and anti-oxidative stress,insulin sensitive index showed that serum lipids were positively correlated with oxidative stress and insulin resistance,indicated that KGM treatment improved the oxidative stress and insulin sensitive by regulating the serum lipids.Correlation analysis between clinical physiological markers of diabetes and bacteria at phylum showed that Bacteroidetes/Firmicutes,Actinobacteria,Bacteroidetes,Deterribacteres,Proteobacteria negatively correlated with hypoglycemic and hypolipidemic activities,while Firmicutes,Tenericutes and TM 7 showed the opposite tend.At genus level,Allobaculum,Dorea,Bifidobacterium,Blauti,Streptococcus and Turicibacter were negatively correlated with hypoglycemic and hypolipidemic activities,Lactobacillus,Parabacteroides showed the opposite tend,indicated that KGM treatment could ameliorate the glucose and lipids metabolism and insulin sensitive in diabetic rats through modulating the disordered intestinal flora.Venn comparison between metabolomics and 16S rRNA sequencing showed that clusters including cholic acid/deoxycholic acid,phosphatidyl ethanolamine,unsaturated fatty acid,aromatic amino acid,basic amino acid,branched chain amino acids and pyrimidine were significantly changed in liver and colonic contents,and these clusters were mainly involved in phenylalanine,tyrosine and tryptophan metabolism,phenylalanine metabolism,glycerolipid metabolism,conversion of pentose and glucuronic acids,tyrosine metabolism,arginine and proline metabolism and cysteine and methionine metabolism,KGM treatment maintenance the mucosal integrity,decrease the gene abundance involved in amino acids,lipopolysaccharide and secondary bile acids metabolism,indicated that KGM treatment could balance host metabolism via regulating intestinal flora disorder,maintenance the mucosal function integrity,decreasing the gene abundance related to amino acids,lipopolysaccharide and secondary bile acids metabolism and decreasing the transmittance of harmful metabolites.In conclusion,anti-diabetic activities of the three different sources glucomannans were studied in systematically.All of the three kinds of glucomannans processed certain anti-diabetes activities:improved the symptoms of hyperglycemia and hyperlipemia in diabetic rats,increased the insulin sensitive and glucose tolerance;ameliorated the metabolism of amino acids,saccharides,cholic acids,purine,pyrimidine and lipids in serum and liver;regulated the intestinal flora disorder.Besides,compared the three kinds of glucomannans,KGM was superior to DOP and AGP in anti-hyperglycemia,anti-hyperlipidemia and intestinal flora regulation.KGM antidiabetic mechanisms including improving glucose and lipid metabolism,alleviating oxidative stress injury,maintenance the structure integrity of function tissues,regulating the amino acids,cholic acid,saccharides,lipid and carnitine metabolism,modulating intestinal flora disorders,etc..Compared the three different dose groups,80 mg/kg KGM treatment was superior to 40 and 160 mg/kg KGM treatment in anti-hyperglycemia,anti-hyperlipidemia and intestinal flora regulation.