The binding of benzopyranes to human serum albumin. A structure-affinity study

The binding of several benzopyranes to serum albumin was studied by equilibrium dialysis at pH 7.4 in a 67 mM sodium phosphate buffer at 37 degrees C. The equilibrium data were analyzed using a computer program for curve fitting. The binding isotherm for warfarin, 4-hydroxycoumarin, 4-chromanol, coumarin, 3-acetylcoumarin, and benzoic acid can be described by two stoichiometric dissociation constants. Elimination of the 4-hydroxyl group in the coumarin chemical structures decreases the binding affinity of the compounds on the primary binding site of serum albumin, with 4-chromanol the smallest ligand which binds to seroalbumin with high affinity. Thus, the affinity of 4-benzopyranol and the 4-hydroxybenzopyranones greater than that of benzopyranones. On the other hand, elimination of the 2-oxo group in the benzopyranone chemical structures decreases affinity for the secondary binding site.