Spectroscopic evaluation of Isoxsuprine hyreochloride interactions with human serum albumin

Isoxsuprine (Fig. 1) is a drug that used as a vasodilator in human. It causes adirect relaxation of vascular and uterine smooth muscles [1]. Human serum albumin (HSA) acts as areservoir and transport protein for endogenous (e.g. fatty acids or bilirubin) and exogenous compounds(e.g. drugs or nutrients) in the blood [2]. The binding of a drug to albumin is a major determinant of itspharmacokinetic and pharmacodynamic profile. In this study, the interaction between of Isoxsuprine andhuman serum albumins at physiological like conditions was investigated. Spectroscopic methods such asFourier transform infrared (FT-IR), UV–Vis, fluorescence and circular dichroism (CD) spectroscopy wereused to analysis of this interaction. The results indicate that there is a considerable quenching of theintrinsic fluorescence of HSA on binding with drug. The binding of drug with protein is characterized byone high affinity binding site with the association constants of the order of 105. Thermodynamic analysisshowed that HSA was combined with Drug, mainly by van der Waals or hydrogen interactions. Themolecular distance, r, between protein (Donor) and Isoxsuprine (acceptor) was obtained according toForster’s theory of non-radiation energy transfer. The circular dichroism results represented thatIsoxsuprine induced a decrease in content of the α-helical structure of protein. We hope that results of ourstudy make a better understanding of the extent of distribution of many drugs in the blood and theinteraction with proteins.

کلیدواژه ها:

Isoxsuprine hydrochloride ، Human serum albumin ، Fluorescence ، Fourier transform infrared