Interaction study of ciprofloxacin with human telomeric DNA by spectroscopy and molecular docking

The interaction of ciprofloxacin (CIP) with human telomeric DNA was studied in vitro using multi-spectroscopy and molecular modeling methods. The hypochromic effect with a red shift in ultraviolet (UV) absorption indicated the occurrence of the interaction between CIP and DNA. The fluorescence quenching of CIP was observed with the addition of DNA and was proved to be the static quenching. The binding constant was found to be 9.62 × 104 L mol−1. Electrospray ionization mass spectrometry (ESI-MS) result further confirmed the formation of 1:1 non-covalent complex between DNA and CIP. Combined with the UV melting results, circular dichroism (CD) results confirmed the existence of groove binding mode, as well as conformational changes of DNA. Molecular docking studies illustrated the visual display of the CIP binding to the GC region in the minor groove of DNA. Specific hydrogen bonds and van der Waals forces were demonstrated as main acting forces between CIP and guanine bases of DNA.

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► Multi-spectroscopy and molecular docking methods were combined.
► CIP is likely to insert into the minor groove of DNA.
► ESI-MS was used to deduce the stoichiometric ratio of DNA–CIP complexes.
► The interaction of CIP could destabilize DNA observed by CD spectra.
► Hydrogen bonds and van der Waals were main acting forces between CIP and DNA.