Molecular property–binding affinity relationship of flavonoids for common rat plasma proteins in vitro

The structural difference of flavonoids strongly affects the binding process with plasma proteins. This work in here mainly concerns about the molecular property–binding affinity relationship of dietary flavonoids for common rat plasma proteins (CRPP). The magnitudes of binding constants between flavonoids and CRPP were within the range of 104–105 L/mol and the number of binding sites (n) was determined as 1.02 ± 0.19. These data were much smaller than the affinities between flavonoids and purified bovine and human serum albumins. The hydroxylation on rings A, B and C of flavonoids significantly affected the binding affinity. The glycosylation of dietary flavonoids decreased the binding affinity and the C2C3 double bond hardly affected it. The galloylated catechins have higher binding affinities for CRPP than non-galloylated catechins. Flavonoids played as a hydrogen bond acceptor when bound to CRPP. The flavonoids with high topological polar surface areas (TPSA) are bound tightly while those with low TPSA are not.