Characterization of the interaction between ligustroflavone and bovine serum albumin

The interaction of ligustroflavone with bovine serum albumin is investigated by affinity capillary electrophoresis, ultraviolet–visible absorption spectroscopy, and fluorescence quenching methods in this ariticle. Affinity capillary electrophoresis gives binding constants (Ka) at near-physiological conditions. The mobility ratio (M) was selected to deduce Ka, which effectively eliminates the influence of electro-osmotic flow. The fluorescence quenching method provides quenching constant Ksv, binding site number n, and binding constants Kb. The fluorescence results indicate that bovine serum albumin fluorescence quenching is mainly a static quenching process. The Ka value (7.1089×104) obtained from affinity capillary electrophoresis is in agreement with Kb (8.0057×104) from fluorescence spectroscopy, showing that ligustroflavone has great affinity toward bovine serum albumin. A complex formed between ligustroflavone and bovine serum albumin was evident from the data of ultraviolet–visible absorption spectroscopy, which is consistent with the fluorescence static quenching result. Furthermore, the thermodynamic parameters of the negative ΔH and ΔS values obtained by affinity capillary electrophoresis showed that the van der Waals interactions and hydrogen bond played important roles in the binding of ligustroflavone to bovine serum albumin. The data obtained in this paper can help us in gaining some insights on a possible drug/protein interaction.