Molecular structure-affinity relationship of natural polyphenols for bovine γ-globulin

Scope: The aim of this study was to investigate the interaction between polyphenols and bovine gamma-globulin. Methods and results: The relationship between the structural properties of natural polyphenols and their affinities for bovine gamma-globulin were investigated by fluorescence titration analysis. Methylation of hydroxyl groups on flavonoids weakened the affinities for gamma-globulin by 1.20-38.0 times. Hydroxylation on rings A, B, and C of flavonoids also significantly affected the affinity for gamma-globulin. Glycosylation of flavonoids slightly affected the affinity depending on the conjugation site and the class of sugar moiety. Hydrogenation of the C2=C3 double bond on flavonoids decreased the binding affinities. Galloylated catechins and catechol-type catechins exhibited higher binding affinities for gamma-globulin than non-galloylated and pyrogallol-type catechins. The glycosylation of resveratrol decreased its affinity for gamma-globulin. Conclusion: The binding process with gamma-globulin was strongly influenced by the structural differences of polyphenols.