Spectroscopic studies on binding of Puerarin to human serum albumin

The interaction between Puerarin with human serum albumin has been studied for the first time by spectroscopic methods including fluorescence quenching technology, circular dichroism (CD) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy under simulative physiological conditions. The results of fluorescence titration revealed that Puerarin can strongly quench the intrinsic fluorescence of HSA by static quenching and there is a single class of binding site on HSA. In addition, the studies of CD spectroscopy and FT-IR spectroscopy showed that the binding of Puerarin to HSA changed slightly molecular conformation of HSA. Furthermore, the thermodynamic functions ΔH⁰ and ΔS⁰ for the reaction were calculated to be −9.067 kJ mol⁻¹ and 54.315 J mol⁻¹ K⁻¹ according to van’t Hoff equation. These data suggested that both hydrogen bond and hydrophobic interaction play a major role in the binding of Puerarin to HSA, which is in good agreement with the result of molecular modeling study.