Synergistic interaction of Cu(II) with caffeic acid and chlorogenic acid in α‐glucosidase inhibition

Abstract BACKGROUND Phenolic acids are widespread in foods and are beneficial to human health. However, the role of metal ions in influencing the binding of proteins with phenolic acids that contain the same parent nucleus structure remains unclear. This study investigated the inhibitory effect of caffeic acid (CA) and chlorogenic acid (CHA) on α ‐glucosidase and the biological effect of copper on this process. RESULTS It was found that the esterification of CA with quinic acid could increase the fluorescence quenching, conformational change, and inhibitory effect of CHA on α ‐glucosidase. Copper ions reduced their fluorescence quenching and conformation‐changing ability by binding to the neighboring phenolic hydroxyl group but also increased their ability to alter secondary structure and to inhibit α ‐glucosidase and in vitro anti‐glycation. CONCLUSION Overall, this study shows that the binding of copper ions to the phenolic hydroxyl group adjacent to CA and CHA synergistically inhibited α ‐glucosidase. The findings will offer a theoretical basis for investigating the properties of metal ions and phenolic acid in food chemistry and their potential applications in the prevention and treatment of diabetes mellitus. © 2023 Society of Chemical Industry.