Inhibitory effect of chlorogenic acid on tannase-mediated astringency removal and its mechanism

Phenolic acids, such as chlorogenic acid (CGA) and rosmarinic acid (RA), are added to plant-based beverages as nutritional supplements to enhance their health benefits. However, these compounds can also interfere with the astringency-reducing effect of tannase. This study employed electronic tongue analysis, enzyme inhibition kinetics, spectroscopy, molecular docking and molecular dynamics simulations to investigate the inhibitory mechanisms of CGA and RA on tannase-mediated deastringency.

Our research results indicate that CGA can inhibit tannase-mediated deastringency. It, along with RA, inhibits tannase activity in a non-competitive manner and quenches its intrinsic fluorescence through static quenching. The binding of CGA and RA to tannase led to the exposure of aromatic amino acid residues and a more polar microenvironment. Fourier transform infrared spectroscopy showed that CGA and RA reduced the α-helix and β-turn content in tannase, while increasing the unordered coil content. Molecular docking and dynamics simulations revealed that CGA and RA bind tightly to tannase primarily through hydrogen bonds and van der Waals interactions, occupying the substrate-binding site and thus inhibiting tannase's astringency-reducing activity. Additionally, other polyphenols, such as epicatechin, hesperidin and naringin, were also found to inhibit tannase activity.

The study demonstrated that CGA and RA inhibit the astringency-removal activity of tannase, offering important mechanistic insights for the development of plant-based beverages and deastringency techniques. © 2025 Society of Chemical Industry.