Interactions of different polyphenols with bovine serum albumin using fluorescence quenching and molecular docking.

Polyphenols are responsible for the major organoleptic characteristics of plant-derived foods and beverages. Here, we investigated the binding of several polyphenols to bovine serum albumin (BSA) at pH 7.5 and 25°C: catechins [(-)-epigallocatechin-3-gallate, (-)-epigallocatechin, (-)-epicatechin-3-gallate], flavones (kaempferol, kaempferol-3-glucoside, quercetin, naringenin) and hydroxycinnamic acids (rosmarinic acid, caffeic acid, p-coumaric acid). Fluorescence emission spectrometry and molecular docking were applied to compare experimentally determined binding parameters with molecular modelling. Among these polyphenols, (-)-epicatechin-3-gallate showed the highest Stern-Volmer modified quenching constant, followed by (-)-epigallocatechin-3-gallate. Similarly, (-)-epicatechin-3-gallate had the highest effect on the Circular Dichroic spectrum of BSA, while the changes induced by other polyphenols were negligible. Molecular docking predicted high binding energies for (-)-epicatechin-3-gallate and (-)-epigallocatechin-3-gallate for the binding site on BSA near Trp213. Our data reveal that the polyphenol structures significantly affect the binding process: the binding affinity generally decreases with glycosylation and reduced numbers of hydroxyl groups on the second aromatic ring.