Fluorescence quenching study of moxifloxacin interaction with calf thymus DNA

Authors: YUNKAI LV, Pan Li, Miao-Lun Jiao, Bao-Sheng Liu, Chao Yang

Abstract: Moxifloxacin (MOX) is a fourth-generation synthetic fluoroquinolone antibacterial agent with many important therapeutic properties. Fluorescence quenching was used to study the interaction of MOX with calf thymus DNA (ct-DNA) in aqueous solution. The intercalative binding mode and a static quenching mechanism were confirmed by the Stern--Volmer quenching rate constant (K_q) of 3.48 \times 10^{11} M^{-1} s^{-1} at 298 K. The thermodynamic parameters (\Delta H = --118.4 KJ mol^{-1} and \Delta S = --299.4 J mol^{-1} K^{-1}) were calculated at different temperatures, and they indicate that the main forces between MOX and ct-DNA are hydrogen bonding and Van der Waals force. We proved at the same time the presence of one single binding site on ct-DNA, and the binding constant is 1.28 \times 10^5 M^{-1} at physiological pH. The results may provide a basis for further studies and clinical application of antibiotics drugs.

Keywords: Moxifloxacin, ct-DNA, fluorescence quenching, binding

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