电化学方法研究环丙沙星及其镁、锰络合物与脱氧核糖核酸的相互作用

用电化学的方法,研究环丙沙星(CPFX)及其镁、锰络合物与脱氧核糖核酸(DNA)的相互作用及其极谱伏安行为。结果在0.1mol·L^-1NH₃-NH₄Cl(pH9.2)溶液中,环丙沙星可与DNA作用,产生一新的极谱峰 Ep=-1.72V(vsAg/AgCl),在有Mg²⁺或Mn²⁺存在时则生成三元络合物,产生一电位更负的新峰,峰电位Ep=-1.78V,提示Mg²⁺或Mn²⁺离子参与药物与DNA的作用。对它们的还原峰性质研究表明,电极还原反应是完全不可逆的,电流具有吸附性。本文还探讨了电极还原机理,认为参与电极还原的是三元络合物中的环丙沙星分子,进一步推测CPFX-Mg是嵌入DNA的双螺旋结构中。

INTERACTIONS BETWEEN CIPROFLOXACIN, Mg2+, Mn2+ AND DNA BY ELECTROCHEMICAL METHOD

Interactions between ciprofloxacin (CPFX), Mg2+, Mn2+ and DNA, and their polarographic and voltammetric behaviour were studied. In 0.1 mol.L-1 NH3-NH4Cl buffer solution (pH 9.2), a new reduction peak was obtained by linear-sweep voltammetry with Ep = -1.72 V(vs Ag/AgCl) when adding DNA to CPFX solution, which implies binding of CPFX with DNA. In the presence of Mg2+ or Mn2+, another new sensitive reduction peak, whose peak potential is more negative (Ep = -1.78 V), was obtained which suggested that Mg2+ or Mn2+ took part in the interaction between CPFX and DNA resulting in a ternary complex of CPFX-Mg-DNA. The peak current (ip) is proportional to the concentration of DNA over the range of 1.18 x 10(-4)-3.33 x 10(-4) mol.L-1. In this paper, the properties of the peak current were studied in detail, the result showed that the electrode reaction was irreversible and the ip was influenced by adsorption. The electrode reaction mechanism was also probed into. The CPFX molecule in the complex was reduced on the electrode. Furthermore, CPFX-Mg was shown ot be intercalated between the stacked base pairs of native DNA.