Characterization of the interactions between itraconazole and human and bovine serum albumins by a spectroscopic method

Abstract

The binding of itraconazole (ITZ), a potential antifungal, to human serum albumin (HSA) and bovine serum albumin (BSA) were studied at the physiological acidity (pH=7.4±0.1) by fluorescence and UV-Vis spectroscopies. A decrease in the quenching constant was observed with an increase in temperature. From the fluorescence spectrum and the fluorescence intensity, we observed that ITZ strongly quenches the intrinsic fluorescence of both BSA and HSA by static quenching. Thermodynamic parameters, such as ΔG, ΔH and ΔS, were calculated at different temperatures, showing that electrostatic and hydrophobic interactions were mostly responsible for the binding of ITZ to serum albumin. The distance d between the donor (HAS or BSA) and acceptor (ITZ) was obtained according to fluorescence resonance energy transfer theory (FRET). Synchronous fluorescence and UV-Vis spectroscopy clearly revealed that the microenvironment and the conformation of serum albumins changed during the binding reaction. © Editorial office of Acta Physico-Chimica Sinica.