Mechanism of α-Amylase Inhibition by Gallic Acid

To investigate the inhibitory properties of gallic acid on α-amylase, the inhibitory effect and mechanism of gallic acid on α-amylase were studied by means of inhibition rate, ultraviolet (UV) spectrum, fluorescence spectrum and molecular docking. Results showed that, gallic acid exhibited a significant inhibitory effect on α-amylase, with an IC₅₀ value of 0.06 mmol/L. UV spectral analysis revealed that as the concentration of gallic acid increased from 0.6×10⁻³ mol/L to 1.2×10⁻³ mol/L, the position of the characteristic peak of α-amylase remained relatively unchanged, while the intensity of the absorption peak increased notably. Fluorescence spectroscopy demonstrated the presence of a binding site between gallic acid and α-amylase, with the quenching mechanism identified as static quenching. At a concentration of 1.2×10⁻³ mol/L, the fluorescence quenching rate at 310 K was 19.87% lower than at 298 K. Thermodynamic parameters, ΔH=318.08 kJ·mol⁻¹ and ΔS=1096.85 J·mol⁻¹·K⁻¹, suggested a hydrophobic interaction between gallic acid and α-amylase. Molecular docking results further confirmed the presence of hydrogen bonds, van der Waals forces, and hydrophobic interactions between gallic acid and α-amylase. The aforementioned findings not only corroborated the substantial inhibitory effect of gallic acid on α-amylase (P<0.05), but also elucidated its inhibitory mechanism through diverse experimental methodologies. This research offers a theoretical foundation for the development of functional foods aimed at individuals with type Ⅱ diabetes.