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 B₃ (+)-catechin-(4αÕ8)-(+)-catechin] and B₁ (-)-epicatechin-(4αÕ8)-(+)-catechin]. Interactions observed among the lentil phenolics and BSA were comparable to those observed among the commercial phenolic standards and BSA.