Interaction of low molecular weight phenolics with proteins (BSA)

Mixtures of bovine serum albumin (BSA) and several low molecular weight phenolics were incubated and fractionated using G-50 Sephadex chromatography. Fractions corresponding to the protein and the possible phenolic-protein complexes and fractions corresponding to the free phenolics were collected, and their phenolic content was determined. Among the selected commercial phenolic standards tested (p-coumaric acid, p-hydroxybenzoic acid, protocatechuic acid, caffeic acid and (+)-catechin), the strongest BSA-binding affinity was demonstrated by 3,4-dihydroxy benzoic and cinnamic acids (protocatechuic acid and caffeic acid), whereas p-hydroxybenzoic acid did not interact with BSA. The methodology was also applied to a phenolic extract obtained from lentils containing p-coumaric acid, a p-coumaric acid derivative, (+)-catechin and procyanidins B-3 [(+)catechin-(4 alpha-->8)- (+)-catechin] and B-1 [(-)-epicatechin- (4 alpha-->8)-(+) -catechin]. Interactions observed among the lentil phenolics and BSA were comparable to those observed among the commercial phenolic standards and BSA.