Introduction: Among the four aspects of pharmacokinetics (absorption, distribution, metabolism, and excretion), distribution is the one that this protein controls because most drugs that travel in plasma bind to HSA [1]. Resonance Rayleigh Scattering (RRS) is a special elastic scattering produced when the wavelength of Rayleigh Scattering (RS) is located at or close to the molecular absorption band [2]. Fluorescence spectroscopy has found wide use in studying the physico–chemical properties of proteins, proteins–ligand interactions, and protein dynamics. Fluorescence spectroscopy is often the method of choice for studying properties such as stability, hydrodynamics, kinetics, or ligand binding, because of its exquisite sensitivity [3]. Methods: Fluorescence quenching spectra of HSA were obtained at excitation and emission wavelength of λ ex =280, 295 nm and λ =300-600 nm and for a RRS spectrum can be developed by scanning both the excitation and emission monochromators of a common spectrofluorometer, with Δλ=0 nm ,from 220nm to 600 nm . Results and discussion: Fig.1 shows that the RLS spectrum of HSA-ASA in present of AML that has a sharp and maximum peak at 300 nm. when AML was added to HSA, the RLS intensity was increased. em Then an increase of drug concentration led to a reduction of the RLS intensity .It can be seen that when both AML and ASA is added to HSA , the RLS intensity of this ternary system is much stronger than those binary system, which indicating the formation of the larger ternary complex with HSA in the system. It can be seen from Fig. 1 that the intensities of the fluorescence emission of HSA in the binary and ternary systems decreased gradually when increasing the drug concentrations, this suggests that the chromophore of the protein was positioned in a more hydrophobic environment after addition of ASA and AML. The fluorescence quenching behavior could be analyzed using the Stern-Volmer and Lehrere equations.

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