Hydrophobic interactions of phenoxazine modulators with bovine serum albumin

The interaction of 10-(3'-N-morpholinopropyl)phenoxazine [MPP], 10-(4'-N-morpholinobutyl)phenoxazine [MBP], 10-(3'-N-morpholinopropyl)-2-chlorophenoxazine [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, has been characterized using the following parameters: percentage of bound drug (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 octanol-water partition coefficient, log(10) P. In addition, effect of the displacing activities of hydroxyzine and acetylsalicylic acid on the binding of phenoxazine derivatives to albumin has been studied. Results of the displacement experiments show that phenoxazine benzene rings and tertiary amines attached to the side chain of the phenoxazine moiety are bound to a hydrophobic area on the albumin molecule.