Inhibition mechanism of ferulic acid against α-amylase and α-glucosidase.

The inhibitory mechanisms of ferulic acid against α-amylase and α-glucosidase were investigated by enzyme kinetic analysis, circular dichroism (CD), Fourier-transform infrared (FT-IR) spectroscopy, fluorescence quenching and molecular docking. Results indicated that ferulic acid strongly inhibited α-amylase (IC50: 0.622 mg ml-1) and α-glucosidase (IC50: 0.866 mg ml-1) by mixed and non-competitive mechanisms, respectively. CD spectra and fluorescence intensity measurements confirmed that the secondary structure of α-amylase and α-glucosidase were changed and the microenvironments of certain amino acid residues were modulated by the binding of ferulic acid. FT-IR spectra indicated that the interaction between ferulic acid and α-amylase/α-glucosidase mainly involved in non-covalent bonds. Molecular docking further demonstrated that the interaction forces between ferulic acid and α-amylase/α-glucosidase were hydrogen bonds, with the binding energy of -5.30 to -5.10 and -5.70 kcal mol-1, respectively. This study might provide a theoretical basis for the designing of novel functional foods with ferulic acid.