Comparison of phytochemical composition and anti-hyperglycemic activity of Liubao tea from different fermentation years

Using response surface methodologies, two Liubao tea (LBT) extracts, LBT-5 and LBT-7, were optimized for different fermentation durations. Phytochemical composition analysis assessed the chemical composition and distribution of tea pigments. Their inhibitory effects on glucose-metabolic enzymes were analysed. Furthermore, an insulin-resistant (IR) cell model was constructed to study their regulation of glucose metabolism and underlying mechanism. LBT-7, aged longer, exhi­bited higher polyphenols and pigments. Assessments on glucose-metabolic enzymes and IR regulation confirmed LBT’s capability to enhance glucose consumption, modulate cytokines and activate the IRS-PI3K-Akt-GLUT4 pathway. Notably, LBT-7 demonstrated a stronger effect due to its higher tea pigment