Toxic interaction mechanism of two fluoroquinolones with serum albumin by spectroscopic and computational methods

ABSTRACT

To evaluate the toxicity of two fluoroquinolones (FQs), ciprofloxacin (CPFX), and enrofloxacin (ENFX), at the protein level, their binding modes with bovine serum albumin (BSA) were characterized by multiple spectroscopic and molecular docking methods under simulated physiological conditions. On the basis of fluorescence spectra, we concluded that both FQs greatly quenched the fluorescence intensity of BSA, which was attributed to the formation of a moderately strong complex mainly through electrostatic interactions. Besides, CPFX posed more of an affinity threat than ENFX. The molecular docking methods further illustrated that both CPFX and ENFX could bind into the subdomain IIIA of BSA and interact with Arg 508 and Lys 437, the positively charged residues in protein. Furthermore, as shown by the synchronous fluorescence, UV-Visible absorption and circular dichroism data, both CPFX and ENFX could lead to the conformational and microenvironmental changes of BSA, which may affect its physiological function.

KEYWORDS:

• Fluoroquinolones
• serum albumin
• fluorescence
• molecular docking

Acknowledgments

This work is supported by National Natural Science Foundation of China (21507053). Natural Science Foundation for Outstanding Young Scientists of Shandong Province (BS2015HZ012) and Doctoral Scientific Research Foundation of Linyi University (LYDX2014BS013) are also acknowledged.