Study On The Effects And Mechanisms Of Cyanidin-3-O-glucoside On Glucose Metabolism Regulation

Anthocyanins,a kind of flavonoid widely exist in the cytochylema flowers,fruits,stems,leaves and root organs of plants.Due to its excellent effects in anti-oxidation,anti-tumor,anti-inflammatory,diabetes prevention,weight loss and vision protection,it has been widely used in food and medicine industries.However,study on the regulation of glucose by anthocyanin cyanidin-3-O-glucoside（C3G）and its potential mechanism is still not in-depth.Therefore,the regulatory effect and mechanism of C3G on glucose metabolism are explored,which is of great significance.In this study,the C3G was extracted and purified from the fresh red bayberry fruit as raw materials.Hepatocytes,islet cells,intestinal L cells and db/db diabetic mice were used as research models.The regulatory effect and mechanism of C3G on glucose metabolism were comprehensively evaluated in vivo and in vitro.The main research contents and results are as follows:1.Anthocyanins were separated and purified from the fresh bayberry fruit.The main component of the anthocyanin extract was identified as C3G by UPLC analysis.And three in vitro experiments,named DPPH,ABTS and FRAP,were used to preliminarily evaluate the antioxidant activity of C3G.2.A high-glucose and palmitic acid-induced oxidative stress model in pancreatic islet cells were constructed and further evaluated the antioxidant effect of C3G.It was found that C3G could remove excess ROS and O₂^-in islet cells and enhance the activity of antioxidant enzymes SOD and CAT,thereby effectively alleviating the oxidative stress induced by high-glucose/palmitic acid.The possible molecular mechanism was studied,and it was found that C3G reduced the release of intracellular ROS by up-regulating the expression of PINK1 and PARKIN protein,activating mitochondrial autophagy and clearing damaged mitochondria,and then playing a vital role in alleviating oxidative stress in islet cells.3.Transwell plate was used to construct a co-culture system of islet cells and intestinal L cells in vitro to study the effect of C3G on insulin release.Results showed that although C3G couldn’t directly act on islet cells,it could stimulate the intestinal L cells to secrete GLP-1 via PPAR-β/δsignaling pathway.While GLP-1 could act on islet cells and promote insulin release,C3G regulated the process of insulin release in this indirect way.4.The mechanism of C3G on promoting glucose metabolism was explored in liver cells.C3G was found to effectively promote the process of glucose consumption,glucose uptake and glycogen synthesis in liver cells.It was also clarified that C3G was involved in regulating the glucose metabolism of liver cells by regulating wnt/β-catenin-mediated glucose transporter-1（GLUT-1）expression.5.A high glucose/palmitic acid-induced hepatocyte insulin resistance model was constructed.C3G intervention restore the glucose consumption,uptake and glycogen content in liver cells suffering insulin resistance,which may improve insulin resistance via the PTP1B/p-IRS signaling pathway.6.After 6 weeks of intragastric administration in diabetic db/db mice with C3G,it was confirmed that C3G could improve the symptoms of diabetes in db/db mice,manifested as:1)Reduced fasting blood glucose and body weight,increased oral glucose tolerance,and improved glucose homeostasis were observed;2)Serum insulin and GLP-1 levels were both increased;3)The oxidative stress damage in pancreatic tissue has been relieved to a certain extent,and the insulin release was increased;4)Decreased fat content,and increased glycogen content and GLUT-1expression in the liver.7.To understand whether C3G could interfere with abnormal glucose metabolism in type 2 diabetes by regulating the intestinal microbiota,this study combined transcriptomic to found that C3G intervention not only changed the composition of the intestinal bacterial community,but also affected the metabolic pathways of the microbiota.And the dominant microbiota altered by C3G was closely related to glucose metabolism in vivo.Furthermore,non-targeted metabonomics technology was used to detect of the microbiota in diabetic db/db mice,results showed that C3G not only regulated the composition of the microbiota,but also affected the metabolites related to glucose metabolism（such as short-chain fatty acids）.These results suggested that C3G may alleviate the abnormal glucose metabolism in diabetic db/db mice by regulating the microbiota and its metabolites.