Inhibitory Mechanism of Camellianin A against α-Glucosidase: In Vitro and Molecular Simulation Studies

α-Glucosidase is an important target for type II diabetes treatment, and the search for natural α-glucosidase inhibitors is currently a hot topic in functional food research. Camellianin A is the main flavonoid in the leaves of Adinandra nitida, but research on its inhibition of α-glucosidase is rarely reported. In view of this, the present study systematically investigated the inhibitory impact of camellianin A on α-glucosidase, combining the fluorescence method and molecular docking to explore their interaction, aiming to reveal the relevant inhibitory mechanism. The results indicated that camellianin A possessed excellent α-glucosidase inhibitory activity (IC₅₀, 27.57 ± 0.59 μg/mL), and van der Waals force and hydrogen bonding dominated the binding process between camellianin A and α-glucosidase, with a binding-site number of 1. A molecular docking experiment suggested that camellianin A formed hydrogen bonding with Glu771, Trp391, Trp710, Gly566, Asp568, and Phe444 of α-glucosidase, consistent with the thermodynamic result. Our result can provide a reference for the development of natural α-glucosidase inhibitors.