Natural α-glucosidase inhibitors from Aquilaria sinensis leaf-tea: Targeted bio-affinity screening, identification, and inhibition mechanism

Aquilaria sinensis leaves have long been consumed as a popular replacement tea for lowering postprandial blood glucose levels, but their specific functional components remain unclear. In this study, Aquilaria sinensis leaf-tea 70 % ethanol extract (ALTE) exhibited excellent anti-α-glucosidase activity (IC 50  = 6.93 ± 1.91 μg/mL) and promoted glucose consumption ability in 3 T3-L1 preadipocyte cells. Subsequently phenolic compositions of ALTE were identified for the first time. After that, five potential α -glucosidase inhibitors (α-GIs) including cynaroside-3,5-diglucose, malvidin 3-glucose, epicatechin, epigallocatechin gallate, and dihydromyricetin in ALTE were screened using a targeted bio-affinity ultrafiltration-HPLC/MS method. Moreover, these five α -GIs all showed good anti-α-glucosidase effects and glucose consumption-promoting ability. Furthermore, the binding properties and inhibition mechanisms of five α-GIs to α-glucosidase were further analyzed via enzyme inhibition kinetics, molecular docking, and molecular dynamics simulation. This study confirms that Aquilaria sinensis leaf-tea is effective in preventing post-hyperglycemia in vitro models, suggesting potential for future research in human trials.