Antioxidant activity and stability of α-tocopherol, resveratrol and epigallocatechin-3-gallate in mixture and complexation with bovine serum albumin

Summary Ligand-binding proteins were proposed as ideal carriers for the co-encapsulation of bioactive compounds. Multiple compounds co-encapsulated in food formulation may give rise to different effects on bioactivity and stability. The protein effect on the interplay between bioactive compounds was investigated for selecting suitable co-encapsulation strategy. α-Tocopherol, resveratrol and epigallocatechin-3-gallate (EGCG), as model compounds, interacted with bovine serum albumin (BSA) to form tri-ligand complexes when added in the sequence. For ferric-reducing antioxidant power, the mixtures of α-tocopherol and resveratrol,α-tocopherol and EGCG, resveratrol and EGCG were respectively additive, antagonistic and synergistic, while their ternary mixture were antagonistic. For ABTS+ scavenging capacity, all pairs were antagonistic. BSA improved FRAP of α-tocopherol, resveratrol and EGCG mixture but decreased their ABTS inhibition. Although structural stability and antioxidant activity of resveratrol decreased when alone interacted with BSA, they were improved when α-tocopherol and EGCG were co-presented. Mixing the antioxidants improved their stability and the complexation with BSA can further stabilise them. BSA could thus be a suitable carrier for co-encapsulation/protection of α-tocopherol, resveratrol and EGCG in functional foods.