Bovine alpha-lactalbumin assemblies with capsaicin: Formation, interactions, loading and physiochemical characterization

Numerous human conditions can benefit from diets rich in proteins and bioactives, such as capsaicin (CAP), yet their effective delivery is a sensorial, scientific and technological challenge. This study hypothesized that CAP can form various complexes with native bovine alpha-lactalbumin (holo-ALA) and decalcified-ALA (apo-ALA). Calorimetric and spectroscopic techniques reveals ALA-CAP molecular complexation is spontaneous, exothermic and accompanied by various conformational changes. ITC shows the interaction stoichiometry (n) and binding constant (Kb) for holo-ALA to be 0.87 ? 0.03, 1.54 ? 0.23 ? 105 M-1 and for apo-ALA to be 0.64 ? 0.09, 9.41 ? 2.16 ? 104 M-1. Molecular docking further elucidates that hydrogen bonds govern CAP binding to holo-ALA while hydrophobic interactions dominate binding to apo-ALA in a structural cleft. Finally, this work shows these interactions along with controlled aggregation can be utilized to form CAP-loaded colloids with encapsulation efficiency of 47.1 ? 1.0%. Thus, this study shows great promise in the prospective use of ALA as an edible delivery vehicle for CAP.

Automated summary

This study reveals that capsaicin (CAP) can form molecular complexes with alpha-lactalbumin (ALA), showing potential biological activity. Through calorimetric and spectroscopic techniques, it is found that ALA-CAP molecular complexation is spontaneous, exothermic, and accompanied by various conformational changes. Additionally, the interaction stoichiometry and binding constant for holo-ALA and apo-ALA are determined, with molecular docking further elucidating the mechanisms of CAP binding to ALA.