Noncovalent interaction of dietary polyphenols with bovine hemoglobin in vitro: molecular structure/property-affinity relationship aspects.

The relationship between the structural properties of selected dietary polyphenols and their affinities for bovine hemoglobin (bHB) was investigated by fluorescence analysis. The presence of an additional methoxy group on flavonoids weakened the affinities for bHB by 1.15-13.80 times. Hydroxylation on rings A, B, and C also significantly affected the affinity for bHB. The glycosylation of flavonoids decreased the affinities for bHB by 1 order of magnitude depending on the conjugation site and the class of sugar moiety. Hydrogenation of the C2═C3 double bond also decreased the binding affinity. The galloylated catechins exhibited higher binding affinities for bHB than nongalloylated. The glycosylation of resveratrol increased its affinity for bHB. The binding process with bHB was strongly influenced by the structural differences of dietary polyphenols. The affinities for bHB increased with increasing partition coefficients and decreased with increasing hydrogen bond donor and acceptor numbers of polyphenols, which suggested that the binding interaction was mainly caused by the hydrophobic force.