The conformational structural change of β-lactoglobulin via acrolein treatment reduced the allergenicity

Influence of phloretin on acrolein-induced protein modification and physicochemical changes in a dairy protein model

Acrolein (ACR) is an α,β-unsaturated aldehyde with high reactivity towards nucleophiles in proteins. In this study, a typical phenolic compound phloretin (Phl) was employed to counteract protein modification induced by ACR (1 mM) in whey protein isolate (WPI, 10 mg/mL). The addition of Phl (2 mM) significantly reduced ACR-induced surge of protein carbonyls (from 1.65 to 0.65 μmol/mg protein) and loss of protein total sulfhydryl content (from 0.28 to 0.24 μmol/mg protein) whilst contributing to further reductions in protein surface hydrophobicity and intrinsic fluorescence. The incorporation of ACR into WPI was effectively interrupted by Phl as visualized by Western blot. Only 2.87 % of ACR remained in the presence of 2 mM Phl with the generation of Phl-ACR adducts, suggesting Phl could partially alleviate protein modification by scavenging of ACR. These findings could have important implications for employment of natural phenolic nucleophiles against the adverse effects of ACR towards dietary proteins.

Novel Approaches for Inhibiting the Indoor Allergen Der f 2 Excreted from House Dust Mites by Todomatsu Oil Produced from Woodland Residues

House dust mite (HDM) is a globally ubiquitous domestic cause of allergic diseases. There is a pressing demand to discover efficient, harmless, and eco-friendly natural extracts to inhibit HDM allergens that are more likely to trigger allergies and challenging to be prevented entirely. This study, therefore, is aimed at assessing the inhibition of the allergenicity of major HDM allergen Der f 2 by todomatsu oil extracted from residues of Abies Sachalinensis. The inhibition was investigated experimentally (using enzyme-linked immunosorbent assay (ELISA), surface plasmon resonance (SPR), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)) and in silico using molecular docking. The results showed that todomatsu oil inhibits the allergenicity of Der f 2 by reducing its amount instead of the IgG binding capacity of a single protein. Moreover, the compounds in todomatsu oil bind to Der f 2 via alkyl hydrophobic interactions. Notably, most compounds interact with the hydrophobic amino acids of Der f 2, and seven substances interact with CYS27. Contrarily, the principal compounds fail to attach to the amino acids forming the IgG epitope in Der f 2. Interestingly, chemical components with the lowest relative percentages in todomatsu oil show high-affinity values on Der f 2, especially β-maaliene (-8.0 kcal/mol). In conclusion, todomatsu oil has been proven in vitro as a potential effective public health strategy to inhibit the allergenicity of Der f 2.