Synthesis, structural characterization, and in-vitro cytotoxicity of zinc-levofloxacin ligand

Background: This study aimed to modify levofloxacin and evaluate its cytotoxicity as well as the synthesis, characterization and physical evaluation of mixed ligand zinc complex with the third generation quinolones’ representative, levofloxacin. Levofloxacin coupled to zinc through one pyridone and one carboxylate oxygen as well as with two nitrogen atoms from the heteroligand, as demonstrated by the complexation of zinc (II) metal ion with the deprotonated ligand and heteroligand. The identification of the complex structure was carried out using Fourier Transform Infrared Spectroscopy, Hydrogen-Nuclear Magnetic Resonance, melting point, and UV–visible spectrophotometry. Results: Binding of the zinc on the two donor -N- atoms of 1,10-phenanthroline, the obtained ligand was pale yellow powder with melting point, 260-263 ℃. The Fourier Transform Infrared spectra, v(C=O) is responsible for the strong band located at 1722.43 cm-1 in the levofloxacin spectrum. The ligand spectra lack this peak, and its place is occupied by strong distinctive bands located at 1718.58 cm-1 and 1620.21 cm-1. Concerning UV-visible spectra, the spectra of levofloxacin and the ligand are the same, with a few little variations. Hydrogen-Nuclear Magnetic Resonance spectra of the ligand showed broader signals. The majority of the hydrogen atoms in the levofloxacin molecule exhibit an obvious shift to the downfield region in the zinc complex spectrum. The cytotoxic behavior of the synthesized mixed complex was performed by methylthiotetrazolium assay. It was discovered that following treatment with the compound, HRT-18 cell viability and proliferation rates dropped. The 67-year-old male patient's large intestine included colorectal cancer cells known as HRT-18 cells, which were obtained from his adenocarcinoma. Conclusions: Through in vitro research, we discovered that complex at 1000 and 500μg/ml significantly cytotoxically affected the HRT-18 colorectal cancer cell line. The study concluded that the synthesized mixed complex (Levofloxacin coupled to zinc) is a potential cytotoxic agent against HRT-18 colorectal cancer cell line.