Mechanism of Astragali Radix Vesicle-like Nanoparticles for Reducing Blood Glucose in db/db Diabetic Mice by Regulating Gut Microbiota / 中国实验方剂学杂志

ABSTRACT

Objective:To study the extraction method and characteristics of vesicle-like nanoparticles （VLNs） in Astragali Radix decoction， and to explore the mechanism of the VLNs in reducing blood glucose by regulating the gut microbiota of db/db diabetic mice. Method:Ultracentrifugation and size exclusion chromatography were used to enrich VLNs from Astragali Radix decoction， and the morphology， particle size and concentration of the VLNs were analyzed by transmission electron microscope and nanoparticle tracking analyzer. The db/db diabetic mice were randomly divided into model group， Astragali Radix VLNs high-， medium- and low-dose （21.1， 10.6， 5.3 g·kg^-1） groups and metformin group （0.25 g·kg^-1） according to their blood glucose levels. There were 7 mice in each group， and another 7 C57BL/6 mice were set as the normal group. The mice were given intragastrically for 3 weeks （once a day）， and the changes of fasting blood glucose were observed every week. Hematoxylin-eosin （HE） staining was used to observe the pathological morphology of liver and pancreas of diabetic mice. The feces of mice were collected for 16S rRNA diversity detection of intestinal microbes. Result:The size of the nanoparticles obtained by the two methods was about 200 nm. Astragali Radix VLNs extracted by ultracentrifugation had a typical saucer-like shape with the concentration of 3.0×10¹¹ particles·mL^-1. The morphology of Astragali Radix VLNs obtained by size exclusion chromatography was relatively poor with the concentration of 2.2×10¹¹ particles·mL^-1. After 3 weeks of administration， compared with the model group， Astragali Radix VLNs high-， medium- and low-dose groups could significantly reduce the fasting blood glucose of diabetic mice （<italic>P</italic><0.05， <italic>P</italic><0.01）. The VLNs could improve the gut microbiota dysbiosis， significantly decrease the ratio of Firmicutes/Bacteroidota， and increase the relative abundance of beneficial bacteria and reduce the relative abundance of harmful bacteria. Conclusion:Astragali Radix VLNs may reduce the blood glucose of db/db diabetic mice by adjusting the ratio of Firmicutes/Bacteroidota in the intestinal flora.