Theaflavin 3′-gallate activates G protein-coupled receptor 55 (GPR55) and enhances GLP-1 secretion via Ca2+/CaMKII/ERK signaling in enteroendocrine STC-1 cells, mitigating postprandial hyperglycemia in mice

Black tea-theaflavins lower postprandial hyperglycemia by raising plasma GLP-1 and insulin levels in mice. Theaflavin-3′-gallate (TF2B) effectively activates GPR55, and promotes GLP-1 release via Ca 2+ /CaMKII and ERK1/2 pathways in STC-1 cells.