Plasma protein binding of dietary polyphenols to human serum albumin: A high performance affinity chromatography approach.

Herein, the protein binding rates of structurally different flavonoids to human serum albumin (HSA) were elucidated by applying the high performance affinity chromatography (HPAC). The flavonoids with hydroxyl groups on ring A showed a higher protein binding rate compared with those that there was no hydroxyl on ring A. However, the hydroxylation of ring B lowered the protein binding rate. It was also found that an additional methoxy group in flavone ring A would decrease the protein binding rate. Nevertheless, the methoxy group in flavanone ring A (position 6) and isoflavone ring B (position 4') increased the protein binding rate. Methoxy group at other positions of flavonoids slightly enhanced or no significantly affected the binding rates on human serum albumin. Hydrogenation of C2C3 double bond of flavonoids decreased the protein binding rate and had the same effect as glycosylation which decrease the protein binding rate by 5%-25%.