The Interaction And Functional Effects Of Bovine Whey Proteins With Chloroquine Or Astaxanthin

The whey proteins in milk are composed of β-lactoglobulin,α-lactalbumin,bovine serum albumin and lactoferrin,which play a potential role in the encapsulation,protection and transport of bioactive ingredients.The water-soluble small molecule chloroquine is a widely used common medicine,but it has some side effects,especially will bring gastrointestinal injury.Similarly,the lipid-soluble small molecule astaxanthin has strong antioxidant capacity,but its low stability has hindered its use as a functional factor in the food system,and affected the sensory quality of many products.Studies have suggested that food may influence drug absorption,and that the high amount of protein in milk may lessen the damage of powerful drugs,but direct evidence for this hypothesis has been lacking.In addition,there have been several examples showing that some proteins can interact with astaxanthin to stabilize astaxanthin,but there are few relevant studies on bovine whey proteins.In this paper,chloroquine,astaxanthin and four components of bovine whey proteins were formed into complexes by means of spectral methods and molecular modeling technology,so as to study the interaction mechanism between the two small molecules and bovine whey proteins,and explore the influence of composite on the structure of proteins and small molecules,as well as the effects and changes of composite on the functional application of small molecules.The results are as follows:1.β-lactoglobulin,α-lactalbumin,bovine serum albumin and lactoferrin can interact with chloroquine and astaxanthin,respectively.The most likely binding sites of chloroquineprotein and astaxanthin protein were simulated by molecular docking.2.The crystal structure of the 1:1 binding of β-lactoglobulin and chloroquine was analyzed by X-ray diffraction,and their binding was proved at the atomic level,revealing that the binding forces were hydrophobic interaction and hydrogen bonding.A new binding site of hydrophobic small molecules to β-lactoglobulin,the hydrophobic inlet of β-hydrophobic bucket,was discovered.3.The combination with chloroquine did not affect the gastrointestinal digestion of the four whey proteins.The formation of whey protein-chloroquine complex reduced the toxicity of chloroquine to gastrointestinal cells(GES-1 and Caco-2 cells),especially intestinal cells,and promoted the absorption of chloroquine into the single cell layer of Caco-4.Based on the determination of the molar absorption coefficient of astaxanthin,the protein-astaxanthin 1:1 complexes after heat treatment had higher retention rate and better heat resistance than pure astaxanthin.The antioxidant activity of the complexes aqueous solution could be greatly improved by combining with whey proteins,especially lactoferrin.In this study,it is proved that binding with proteins can alleviate the side effects of water-soluble chloroquine and facilitate absorption,and binding to proteins as a mean of astaxanthin protection can improve the stability and availability of lipid-soluble astaxanthin.