| Wuyi rock tea has a hypoglycemic effect and it is generally believed that its hypoglycemic effect is achieved by improving the sugar tolerance and regulating the related activity of islet cells.Recent literature studies have shown that the development of diabetes is closely related to the intestinal flora.In this study,the hypoglycemic effect of Wuyi rock tea and its effect on intestinal microflora were elucidated through experiments in rats.The biochemical indexes of tea polysaccharides,tea polyphenols,etc.were measured in six Wuyi rock tea varieties to calculate the correlation coefficient.The principal components such as the gravel chart,the contribution rate of each principal component,and factor loading matrix were anlyzed.Then,a principal component evaluation model for potential?-amylase activity inhibition by Wuyi rock tea was established.According to the evaluation model,the score of Wuyi Narcissus was the highest,and the contribution rate of its principal component reached 89.109%.Further experiments were conducted on the inhibition of alpha-amylase activity by 6 strains of Wuyi rock tea,the inhibition of amylase activity by Wuyi Narcissus was the highest rate of 63.4%,and the half inhibitory concentration(IC50)was 12.44 mg·mL-1.Therefore,Wuyi Narcissus was selected for the following experiments.The SPF-grade Wistar rats were treated by streptozotocin(STZ)to establish the diabetic rat model.Diabetic rats were infused with Wuyi rock tea of high dose(4.29 g·kg-1),medium dose(2.89 g·kg-1)and low dose(1.43 g·kg-1)every day for 30 d.Daily fasting blood glucose and area under curve(AUC)were taken as the usual observation indicators to monitor the rats.Fasting serum high-density lipoprotein cholesterol(HDL-C),insulin(INS),triglyceride(TG),total cholesterol(TCC)and low-density lipoprotein cholesterol(LDL-C)were measured to determine the biochemical responses of rats to tea.At the same time,liver cells of rats were stained with HE and pathological observations were performed.The results showed that Wuyi rock tea of high,medium and low dose could all inhibit the fasting blood glucose;improve glucose tolerance with a good dose-response relationship;reduce the content of cholesterol and triglyceride in diabetic rats;improve the content of fasting serum insulin and insulin sensitivity in rats and reduce insulin resistance index;improve liver cell regular arrangement.The impact of Wuyi rock tea on the intestinal flora in diabetic rat was investigated.Based on the Illumina MiSeq sequencing platform,the DNA of the rat intestinal content in the V3-V4 region was sequenced to analyze the changes of the intestinal flora.The results showed that,the diversity of intestinal flora in the diabetic rats was significantly increased compared with that in the blank control group and Wuyi rock tea could effectively reduce the diversity with a significant inhibitory effect by high-dose tea;the intestinal flora from phylum to genus were significantly changed in diabetic rats compared with the blank control group,with Bacteroidetes significantly decreased and Proteobacteria significantly increased,and Bacteroidetes was increased and Proteobacteria was decreased in diabetic rats by Wuyi rock tea with the change level positively related to the dose of Wuyi rock tea.In the genus level,the relative abundance of coli group in diabetic rats treated by Wuyi rock tea is slightly lower than the blank control group,the abundance of Allobaculum in diabetic rats treated by Wuyi rock tea was increased compared with the diabetic group.The heatmap diagrams of the specific bacteria in response to Wuyi rock tea showed the relative abundance-of Enterorhabdus,Escherichia-Shigella and Christensenellaceae_R-7_group was significantly increased in in diabetic rats,and Wuyi tea could significantly reduce the relative abundance of Enterorhabdus with the best effect by the high dose tea;in addition,relative abundance of Romboutsia,Ruminococcaceae_UCG-013,Bifidobacterium,Allobaculum and other was significantly decreased in diabetic rats,and the relative abundance of Bifidobacterium and Romboutsia was significantly increased,with the best effect by the high dose tea.In conclusion,Wuyi rock tea has not only a significant hypoglycemic effect,but also a significant regulatory effect on the intestinal flora in diabetic rats. |
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