Effects Of Barley β-glucan On Blood Glucose And Intestinal Flora

Highland barley is mainly planted in alpine areas.It is a medicinal and edible grain crop,and can also be used for brewing products and raising animals.It has high nutritional components,and has the effects of lowering blood glucose,lowering blood lipid,anti-oxidation and improving body immunity.It also has the beneficial activity of regulating intestinal flora.A large number of researchers have attributed the functional activity of highland barley to its richβ-glucan.Studies have shown thatβ-glucan can improve diabetes,hyperlipidemia and colitis.It also has the effect of regulating the structure of intestinal flora and enriching probiotics.In order to explore the functional activity of highland barleyβ-glucan and improve the utilization rate of highland barley in Tibet,this study used blue highland barley in Tibet as raw material to prepare highland barleyβ-glucan(HBG)according to previous extraction conditions.Firstly,the content of the basic components of the prepared HBG were determined.Then,animal experiments were conducted to explore the alleviating effect of HBG on type 2 diabetes(T2D)mice induced by high-fat diet(HFD)combined with streptozotocin(STZ).Finally,HBG was used as a carbon source for in vitro fecal fermentation to further explore the regulatory effect of HBG on fecal microorganisms in healthy group and type 2 diabetes group.The main results are as follows:(1)Preparation of HBG.In this study,HBG was extracted by alkali extraction,enzymatic hydrolysis,ammonium sulfate precipitation and graded alcohol precipitation,and the content of its basic components was determined.The total sugar content of HBG was 90.7±2.3%,β-glucan content was 81.9±1.9%,and protein content was 3.01±0.11%.The molecular weight of HBG was determined to be 5.30×10~4Da by gel permeation chromatography(GPC).(2)After four weeks of HBG intervention,HBG can inhibit the growth of body weight and organ weight of T2D mice,and can also reduce the fasting blood glucose(FBG)of T2D mice in a time-dependent manner.In addition,HBG improved abnormal lipid metabolism in T2D mice,mainly reflected in reducing total cholesterol(TC),triglyceride(TG)and low-density lipoprotein cholesterol(LDL-C),and increasing high-density lipoprotein cholesterol(HLD-C).It can also improve the oxidative stress of T2D mice by increasing the concentration of antioxidant catalase(CAT)and glutathione(GSH)and reducing the oxidation products malondialdehyde(MDA)and nitric oxide(NO).The levels of tumor necrosis factorα(TNF-α),interleukin 1β(IL-1β)and alanine aminotransferase(ALT)were decreased to alleviate the inflammatory response and liver damage in T2D mice.(3)HBG can increase the concentration of short chain fatty acids(SCFAs)in cecal contents of T2D mice,including acetic acid,propionic acid and butyric acid.It also had a certain regulatory effect on the intestinal flora of T2D mice,mainly reflected in:HBG increased the abundance of Firmicutes,Actinobacteria and Verrucomicrobia at the phylum level,and decreased the abundance of Bacteroidota and Proteobacteria.At the level of family and genus,the abundance of Streptococcaceae,Eggerthellaceae and Lachnospiraceae＿UCG-006 was increased,and the abundance of Parasutterella and Helicobacter was reduced.(4)After in vitro fermentation of feces from healthy group and T2D group with HBG as carbon source for 24 h,it was found that HBG had similarities in the fermentation of feces from different sources,but there were also some differences.The microbial diversity of feces in the healthy group decreased after HBG fermentation.At the genus level,the abundance of Lactobacillus increased significantly,and the abundance of Faecalibacterium,Ruminococcus,Roseburia and Enterococcus also increased.However,the abundance of Shigella Bacteroides,Peptoniphilus,Peptostreptococcus and unclassified＿Enterobacteriaceae was reduced.In addition,microbial diversity also showed a downward trend after HBG fermented T2D feces.It also affected the microbial composition of the fermentation broth,such as the increased abundance of Bifidobacterium,Enterococcus and Lactobacillus.In addition,the abundance of Shigella,a harmful bacterium,decreased significantly,and the abundance of Dialister and Streptococcus also decreased.In conclusion,β-glucan extracted from highland barley in Tibetan region of China has certain effects on alleviating symptoms such as hyperglycemia in T2D mice.In addition,it also has the probiotic effect of regulating intestinal microorganisms.These experimental results provide some theoretical basis for the application of highland barley in health products.