Fabrication and characterization of functional protein–polysaccharide–polyphenol complexes assembled from lactoferrin, hyaluronic acid and (−)-epigallocatechin gallate

Proteins, polysaccharides, and polyphenols can be assembled into ternary complexes with functional attributes that combine the desirable facets of each individual component. In the present work, we characterized the interactions among lactoferrin (LF), hyaluronic acid (HA) and (-)-epigallocatechin gallate (EGCG) dispersed in aqueous solutions at various pH values (2 to 9), HA levels (0 to 0.5 wt%), and EGCG levels (0 to 0.105 wt%). The antioxidant activity of the complexes was also evaluated. The ternary complexes formed macroscopic hydrogels at pH 2, microgel dispersions at pH 3, and soluble complexes at pH > 4. Information about the role of hydrogen bonds, electrostatic forces, and hydrophobic interactions was obtained using spectroscopic methods. The antioxidant activity of the ternary complexes was much higher at pH 5 than at pH 3, which was attributed to the ability of the hydrogels to inhibit the access of the free radicals generated in the aqueous phase to EGCG trapped inside. These results may be useful for optimizing the formulation of effective delivery systems for natural antioxidants.