A tetrahedral Zn(II) complex with the second generation fluoroquinolone,
norfloxacin, was prepared and characterized (NOR–Zn complex, NZC). The antibacterial
efficiency of the NZC was tested on two Gram-positive and four Gram-negative bacteria by
minimum inhibitory concentration method. The cytotoxic potential of NZC on MDA
(human breast adenocarcinoma), Caco-2 (human colon adenocarcinoma), and Hela (human
cervix carcinoma) cell lines was studied. The DNA interaction property of the NZC has been
investigated using UV–vis, fluorescence, Fourier transform infrared, as well as cyclic
voltammetry methods. Intrinsic binding constant (Kb), thermodynamic, and other spectroscopic
and voltammetric data indicate that the NZC has more affinity for DNA than for
norfloxacin and interacted with DNA via two modes: electrostatic and outside hydrogen
binding. The proposed DNA binding mode supports the large enhancement in the cytotoxicity
and antibacterial activity of NZC.
