Interactions between fluoroquinolones and bovine serum albumin by fluorescence method and affinity capillary electrophoresis

The interactions between fluoroquinolones (sparfloxacin, lomefloxacin, norfloxacin, levofloxacin, fleroxacin and pefloxacin) and bovine serum albumin were investigated by affinity capillary electrophoresis and fluorescence quenching method. The binding molar ratio was 1:1 and the values of binding constants were all at the magnitude level of 10(4) L/mol. Both van der Waals interaction and hydrogen bonds were involved in the binding process of these fluoroquinolones to BSA. The ACE results also reveal that with the increasing of buffer pH values and ionic strength, the interaction strength became weaker to a certain extent. The FL results and UV-Vis spectrum indicate that the fluorescence quenching was mainly arisen from static quenching by complex formation. The obtained results of these two methods may help us in gaining some insights on possible fluoroquinolones/BSA interactions and in evaluating the drugs' pharmacokinetic profiles.