Studies on the inhibition mechanism of α-glucosidase by kaempferide: Enzyme kinetic, multi-spectroscopy and molecular docking techniques

α-Glucosidase (α-Glu) is an enzyme that lowers postprandial blood glucose after breaking down complex carbohydrates. Kaempferide is the principal flavonoid active ingredient in plants and is widely found in fruits, vegetables, and beverages. This study found that kaempferide has the potential to inhibit α-Glu activity to treat type 2 diabetes. The results showed that kaempferide (IC 50  = 55.35 ± 0.27 μM), serving as a mixed-type inhibitor for α-Glu, exhibited sensibly superior inhibition of α-Glu than acarbose (IC 50  = 414.08 ± 10.73 μM). In addition, the outcomes from fluorescence quenching, 3D fluorescence, synchronous fluorescence, CD spectroscopy, and molecular docking analysis showed that kaempferide can not only chelate with α-Glu by hydrogen bonding and Van der Waals forces, but also affect the secondary structure and activity of the enzyme. After oral administration of sucrose in mice, kaempferide effectively reduces postprandial blood glucose (PBG) and without any other adverse symptoms. In summary, this study has the potential to contribute to the development of functional foods for the prevention and management of type 2 diabetes (T2DM).