Covalent modification of β-lactoglobulin by (-)-epigallocatechin-3-gallate results in a novel antioxidant molecule.

β-lactoglobulin (β-lg), the predominant protein in bovine whey, was chemically modified by (-)-epigallocatechin-3-gallate (EGCG) to develop a biomacromolecule with antioxidant activity. The EGCG-modified β-lg was characterized by SDS-PAGE, MALDI-TOF MS and intrinsic fluorescence spectroscopy. The antioxidant properties of EGCG-modified β-lg was assessed using DPPH radical scavenging activity, iron chelating ability, and inhibition of Cu2+-induced LDL oxidation. SDS-PAGE and MALDI-TOF MS results indicated the dimerization of β-lg after EGCG modification. Intrinsic fluorescence spectra suggested that EGCG modification caused an alteration in the conformational structure of β-lg. The results demonstrated that EGCG-modified β-lg possessed great antioxidant potential in terms of scavenging DPPH radical and chelating ferrous ion. Furthermore, the EGCG-modified β-lg showed a protective effect against LDL peroxidation. The results indicate that EGCG-modified β-lg could provide significant health benefits as an antioxidant.