Comparison of non-covalent binding interactions of six caffeoylquinic acids with β-lactoglobulin: Spectroscopic analysis, molecular docking and embedding of curcumin

In this study, we systematically compared the differences in the interactions of β-lactoglobulin (LG) with three mono-caffeoylquinic acids (MCQAs: 3-CQA, 4-CQA, and 5-CQA) and three dicaffeoylquinic acids (DCQAs: 3,4-DCQA, 3,5-DCQA, and 4,5-DCQA). Based on molecular docking techniques, it was concluded that the non-covalent binding of all six caffeoylquinic acids to LG was dominated by hydrophobic forces, among which the binding ability of DCQAs was stronger. The antioxidant assay revealed that caffeoylquinic acid significantly improved the antioxidant properties of LG, and the best antioxidant properties were achieved with 4,5-DCQA. The DPPH radical scavenging ability was increased by approximately 54 μmol Trolox/g-sample, and the ABTS radical scavenging ability increased by 29.26 μmol Trolox/g-sample. Six non-covalent complexes were used to embed curcumin, and the stability of the formed solution was further investigated and compared.