In vitro study of caffeic acid-bovine serum albumin interaction.

Caffeic acid, a natural product with pharmacological properties, such as DOPA-decarboxylase and 5-lipooxygenase inhibition, has been tested in vitro for its binding ratio to bovine serum albumin. This study was carried out by means of four analytical methods. Equilibrium dialysis has been proved to be the most reliable in determination of total binding sites, while acid precipitation has been evaluated as a model of irreversible binding. A binding ratio between 61 and 95% was observed, also varying according the caffeic acid and albumin concentration, pH and protein conformation. Binding constants were calculated by mathematical fitting to a hyperbolic plot. Other cinnamic acids non-o-diphenolic (ferulic acid, m- and p-coumaric acids) have been proved to have a binding ratio to bovine serum albumin of less than 10%.