Abstract:To explore the inhibitory effects and mechanisms of three flavonoids on α-amylase (porcine pancreatic alpha-amylase, PPA), this study employed enzyme kinetic analysis to evaluate their inhibitory efficacy and mode of action. Multidimensional techniques, including fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy, and molecular docking, were integrated to systematically elucidate the molecular interactions between flavonoids and PPA. Experimental results demonstrated that Luteolin (Lut), Procyanidins (Pro) and Fisetin (Fis) exhibited dose-dependent inhibitory effects on PPA, with IC50 of 0.018, 0.017, 0.007 mg/mL, respectively. Lineweaver-Burk double reciprocal plot analysis revealed that Lut, Pro, and Fis acted as non-competitive synergistic inhibitors. Fluorescence and UV-Vis spectral analyses indicated that the quenching mechanism of PPA by all three flavonoids followed a static quenching pattern, with binding constants exceeding 105 L/mol, suggesting the formation of stable flavonoid-PPA complexes. Thermodynamic parameter calculations and molecular docking simulations further confirmed that hydrophobic interactions and hydrogen bonding were the dominant driving forces for the binding, with the interaction sites located near key catalytic residues (Glu233, Asp197, Asp300, Trp58, and Trp59). These findings highlight the potent PPA inhibitory activity of the tested flavonoids and provide novel insights and theoretical foundations for the development of next-generation PPA inhibitors.