Noncovalent interaction of dietary polyphenols with common human plasma proteins.

Common human plasma proteins (CHPP), also called blood proteins, are proteins found in blood plasma. The molecular structure/property–affinity relationships of dietary polyphenols noncovalently binding to CHPP were investigated by comparing the binding constants obtained from the fluorescence titration method. An additional methoxy group in flavonoids increased their binding affinities for CHPP by 1.05 to 72.27 times. The hydroxylation on the 4′ position (ring B) of flavones and flavonols and the 5 position (ring A) of isoflavones weakened the binding affinities; however, the hydroxylation on other positions of flavonoids slightly enhanced or little affected the binding affinities for CHPP. The glycosylation of flavonoids weakened or slightly affected the affinities for CHPP by 1 order of magnitude. The hydrogenation of the C2═C3 double bond of flavone, 6-hydroxyflavone, 6-methoxyflavone and myricetin decreased the binding affinities about 10.02 to 17.82 times. The galloylation of catechins significantly ...