Studies on the binding of vinpocetine to human serum albumin by molecular spectroscopy and modeling

The interaction between vinpocetine (VPC) and human serum albumin (HSA) in physiological buffer (pH 7.40) was investigated by fluorescence, FT-IR, UV-vis absorption and molecular modeling. VPC effectively quenched the intrinsic fluorescence of HSA via static quenching. The binding site number n and apparent binding constant Ka, corresponding thermodynamic parameters ΔG, ΔH and ΔS at different temperatures were calculated. The synchronous fluorescence and FT-IR spectra were used to investigate the structural change of HSA molecules with addition of VPC. Molecular modeling indicated that VPC could bind to the site I of HSA and hydrophobic interaction was the major acting force, which was in agreement with the binding mode study.