Hydrophobic interactions of phenoxazine modulators with bovine serum albumin

The interaction of 10-(3'-N-morpholinopropyl)phenoxazine [MPP], 10-(4'-N-mo rpholinobutyl)phenoxazine [MBP], 10-(3'-N-morpholinopropyl)-2-chlorophenoxa zine [MPCP], 10-(3'-N-piperidinopropyl)-2-chlorophenoxazine [PPCP] or 10-(3 '-N-morpholinopropyl)-2-trifluoromethylphenoxazine [MPTP] with bovine serum albumin (BSA) has been studied by gel filtration and equilibrium dialysis methods. The binding of these modulators, based on dialysis experiments, ha s been characterized using the following parameters: percentage of bound dr ug (beta), the association constant (K-1), the apparent binding constant (k ) and the free energy change (Delta F degrees). The binding of phenoxazine derivatives to serum transporter protein, BSA, is correlated with their oct anol-water partition coefficient, log(10) P. In addition, effect of the dis placing activities of hydroxyzine and acetylsalicylic acid on the binding o f phenoxazine derivatives to albumin has been studied. Results of the displ acement experiments show that phenoxazine benzene rings and tertiary amines attached to the side chain of the phenoxazine moiety are bound to a hydrop hobic area on the albumin molecule.