海南大叶茶特征多酚对碳水化合物水解酶的抑制机制OA

This study explored the inhibitory potential and mechanism of water extracts and characteristic polyphenols from green and black tea made from the Hainan large-leaf variety against carbohydrate-hydrolyzing enzymes(α-amylase and α-glucosidase).The results showed that green tea had significantly higher total phenolic(61.9 mg/g)and flavonoid(28.79 mg/g)contents and consequently exhibited stronger inhibition against α-glucosidase and α-amylase with half maximal inhibitory concentration(IC50)of 59.10 μg/mL and 14.21 mg/mL than black tea,respectively.Nine characteristic polyphenols were identified,and five core active monomers including epigallocatechin(EGC),epigallocatechin gallate(EGCG),procyanidin B2(PB2),kaempferol-3-O-rutinoside,and ellagic acid were screened out by molecular docking.These compounds demonstrated significant enzyme inhibitory effects and enhanced glucose consumption in 3T3-L1 cells.Mechanistic analysis revealed that the polyphenols inhibited the enzymes in competitive,non-competitive,and mixed-type manners.Fluorescence quenching and molecular simulations confirmed that the polyphenols could interact with the enzymes'active sites(ASP-300/GLU-233 in α-amylase;GLU-296/ASP-269 in α-glucosidase)via a static quenching process,and stable complexes were formed through hydrogen bonding and van der Waals forces,with EGCG-α-amylase and PB2-α-glucosidase complexes showing optimal stability.This study demonstrates that the characteristic polyphenols in Hainan large-leaf tea,particularly in green tea,regulate postprandial glucose through the dual pathways of enzyme inhibition and glucose consumption promotion.At their core,these polyphenols stably bind to the active sites of carbohydrate-hydrolyzing enzymes through multiple mechanisms.