Effects of crude polysaccharides from Coix seeds fermented by Limosilactobacillus reuteri on hyperglycemia and gut microbiota in type 2 diabetic mice

This study aimed to investigate the hypoglycemic effects of polysaccharides (FCSP) from coix seeds fermented by Limosilactobacillus reuteri . The extraction process of FCSP was optimized using Response Surface Methodology, and evaluated the hypoglycemic effects of FCSP both in vivo and in vitro. After process optimization, the extraction rate of FCSP was 8.74%. In vitro studies demonstrated that FCSP reduced oxidative stress levels in IR-HepG2 cells, significantly enhanced the activities of hexokinase (HK) and pyruvate kinase (PK), and promoted glucose consumption and glycogen synthesis. In T2DM mice, FCSP decreased glycated serum protein levels and improved glucose tolerance. The levels of blood lipids and oxidative stress were also significantly ameliorated. Furthermore, FCSP significantly reduced the Firmicutes/Bacteroidetes ratio and enhanced the abundance of beneficial microbiota, including Lactococcus , Akkermansia , Lactobacillus , Bifidobacterium , Weissella and Adlercreutzia in the mouse gut. Overall, these findings provide clear scientific evidence for the hypoglycemic potential of FCSP. • The maximum extraction yield of FCSP was 8.74% under optimized conditions. • FCSP increased the glucose consumption and glycogen content of HepG2 cells, and reduced the oxidative stress level. • FCSP enhanced the abundance of Lactococcus , Akkermansia , Lactobacillus , and Bifidobacterium in the intestines of mice. • FCSP ameliorated hyperglycemia through regulation of glucose metabolism, oxidative stress, and gut microbiota homeostasis.