Synthesis of 2-(4-Methylphenyl)-3-(N-acetyl)-5-(2-hydroxyphenyl)-1,3,4-oxodiazoline and Its Interaction with HSA

2-(4-Methylphenyl)-3-(N-acetyl)-5-(2-hydroxyphenyl)-1,3,4-oxodiazoline (MPAHO) was synthesized and characterized by NMR and IR. The mechanism of the interaction between MPAHO and human serum albumin (HSA) was studied by fluorospectrometry. Significant quenching of fluorescence of HSA was observed by its reaction with MPAHO. Judging from the fluorescence quenching constants obtained by Stern-Volmer equation, fluorescence quenching of HSA by MPAHO was attributed to static quenching. The binding constants, number of binding sites and binding distance were found by applying the equation of site-binding model and Frster nonradiative energy transfer theory. Values of thermodynamic parameters ΔH and ΔS were calculated and based on these results, the binding force between MPAHO and HSA was recognized to be electrostatic attraction. The effect of MPAHO on the conformation of HSA was studied by synchronous fluorospectrometry and three-dimensional fluorescence technology.