Mechanism of seaweed polyphenols interacting with intestinal flora to regulate blood glucose.

Seaweed polyphenols possess hypoglycemic biological functions, but the specific mechanisms remain unclear, which limits their further application. In this study, the area under the blood glucose curve (AUC) of the fourth-period Porphyra haitanensis polyphenols extract (FPPE)-fed mice was significantly reduced by 17.12 ± 0.87%. Moreover, FPPE exhibited α-glucosidase inhibitory activity at 64.39 ± 4.05%. In vitro fermentation experiments showed that FPPE modulated the composition of the gut microbiota, thereby enhancing the production of short-chain fatty acids (SCFAs). Analysis of intestinal flora and metabolites in mice revealed that FPPE selectively enriched hypoglycemic-functional bacteria, such as Bacteroides and Alloprevotella. These bacteria feedback-regulated the production of hypoglycemic polyphenolic substances such as isovitexin and isoquercetin, which showed a strong positive correlation. Further mechanistic studies revealed that FPPE's digest could suppress cellular glucose transport by inhibiting the expression of Sodium Glucose Cotransporter 1 (SGLT1) and glucose transporter 2 (GLUT2), thereby reducing blood glucose levels.