Complexation of trans- and cis-resveratrol with bovine serum albumin, β-lactoglobulin or α-lactalbumin

Clarification of the mechanism of protein-ligand interaction is important for the encapsulation of bioactive components. Trans -resveratrol is labile to convert to cis -isomer during fermentation and storage, but the cis -isomer interaction with proteins has not yet gained as much attention as that of trans -isomer. The influence of resveratrol's isomerization on interaction with ligand-binding proteins was investigated here. Cis -resveratrol exhibited higher affinity for bovine serum albumin than trans -isomer, but the isomerization to cis -isomer decreased the polyphenol affinity for α-lactalbumin and β-lactoglobulin. For each protein, trans - and cis -resveratrol shared the same optimal docking site but showed clear diversity in the second best site. Protein ternary complex could be formed when trans -/ cis -resveratrol were added in the sequence. Moreover, photostability of resveratrol and antioxidant activity of the polyphenol-protein mixtures were also discussed. The results gathered here should provide further insight into protein-polyphenol interactions and be useful for the development of protein-based carriers for the polyphenols.