Caffeoyl substitution decreased the binding and inhibitory activity of quinic acid against α-amylase: The reason why chlorogenic acid is a relatively weak enzyme inhibitor. (1st March 2022)

• Record Type: Journal Article
• Authors: Song, Yi; Li, Wenyue; Yang, Hefei; Peng, Xiaoke; Yang, Xi; Liu, Xuebo; Sun, Lijun
• Is Part Of: Food chemistry. Volume 371(2022)
• Publication Date: 2022-03-01
• Subjects: α-Amylase -- Inhibition -- Caffeoyl moiety -- Binding interactions -- Phenolic acids; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2021.131278
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: Quinic acid (QA) was a competitive inhibitor of α-amylase. Caffeoyl substitution decreased amylase inhibition of QA, remaining inhibition type. Caffeoyl provided chlorogenic acid (CHA) with fluorescence quenching by π-stacking. Thermal stability of amylase depends on enzyme residues where phenolic acids bind with. Caffeoyl decreased binding affinity of QA to α-amylase by changing the binding sites. Abstract: α-Amylase inhibition of chlorogenic acid (CHA) and its component moieties including quinic acid (QA) and caffeic acid (CA) were characterized by IC50, inhibition kinetics, fluorescence quenching, isothermal titration calorimetry, differential scanning calorimetry and molecular docking. QA was found with the highest inhibitory activity in a competitive-mode, and caffeoyl substitution significantly decreased its inhibition but maintained inhibition type. Interestingly, QA hardly quenched α-amylase fluorescence, while CA quenched that significantly without inhibitory activity. This resulted from lack of aromatic ring in QA that can form π-conjugation with α-amylase fluorescent residues. Besides, the binding constant of QA with α-amylase was higher than CHA. Additionally, QA and CA decreased but CHA remained α-amylase thermal stability, indicating that change in α-amylase spatial structure was related with enzyme residue sites involved in interactions with inhibitors, instead of with inhibition effect. Conclusively, caffeoyl substitution decreased α-amylase inhibition of QA through reducing its binding affinity to the enzyme.