Synthesis, Characterization and Biological Studies of Gemifloxacin Mesylate with Nickel(II) and Copper(II)

Abstract

Gemifloxacin mesylate, a fourth-generation fluoroquinolone-type antibiotic, is widely used for community treatment of acquired pneumonia and severe bacterial infections. The Cu(II) and Ni(II) complexes of gemifloxacin mesylate were synthesized by refluxing an aqueous solution of the ligand with the required amount of metal(II) salts in a round bottom flask with 2:1 (L:M) ratio in an oil bath at 90 ºC with a continuous stirring for 4 h. The mixture was kept overnight to obtain a coloured solid complex. The synthesized metal(II) complexes were characterized by physico-chemical parameters and spectral analyses, including UV-Vis, FT-IR and ¹H NMR. The structures of the complexes were further confirmed by elemental (CHNS) and TG-DTA analyses. The spectral findings revealed that metal-ligand interaction has successfully occurred where the ligand acted as a bidentate chelate in the synthesized metal(II) complexes. The IR studies showed that upon complexation the characteristic carboxylic stretching frequency at 1714 cm^-1 disappeared and the pyridone stretching frequency shifted to a lower frequency region. The ¹H NMR data of the complexes confirm the effective interaction between the metal and the ligand via 3-carboxyl group and 4-oxo groups. The thermal and elemental analyses data were also in agreement with the proposed interaction. The ligand as well as its metal(II) complexes showed significant activity against all the studied 11 bacterial strains and one of the fungal strains, Candida sp.