The complex of hypericin with β-lactoglobulin has antimicrobial activity with potential applications in dairy industry

摘要

Using a combination of molecular modeling and spectroscopic experiments, the naturally occurring, pharmacologically active hypericin compound is shown to form a stable complex with the dimeric form of β-lactoglobulin (β-LG). Binding is predicted to occur at the narrowest cleft found at the interface between monomers in the dimeric β-LG. The complex is able to preserve the fluorescence and singlet oxygen photosensitizing properties of the dye. The equilibrium constant for hypericin binding has been determined as K_a = 1.40 ± 0.07 μM~(-1), equivalent to a dissociation constant, K_d = 0.71 ± 0.03 μM. The complex is active against Staphylococcus aureus bacteria. Overall, the results are encouraging for pursuing the potential application of the complex between hypericin and β-LG as a nanode-vice with bactericidal properties for disinfection.