Investigation of nitroxoline-human serum albumin interactions by spectroscopic methods

Nitroxoline is a wide spectrum antibacterial and is one of the most important urinary antiseptics. The interaction between nitroxoline and human serum albumin (HSA) has been investigated systematically by fluorescence spectroscopy, synchronous fluorescence, three-dimensional fluorescence, CD spectroscopy and UV-Vis absorption spectroscopy. The results indicated that the quenching of HSA by nitroxoline was static. The corresponding thermodynamic parameters Δ H , Δ S and Δ G calculated according to van’t Hoff equation revealed that the intermolecular forces acting between nitroxoline and HSA were mainly hydrogen bonding and van der Waals forces. The conformational changes in the interaction were studied by synchronous fluorescence, CD spectroscopy and three-dimensional fluorescence spectra which showed changes in the microenvironment and conformation of HSA.