Synthesis, characterization, and biological activity of cobalt(II), nickel(II), copper(II), and zinc(II) complexes of secnidazole

Thirteen coordination compounds of CoII, NiII, CuII, and ZnII with the biologically active ligand secnidazole were designed, synthesized, and fully characterized. Using UV–Vis–NIR spectroscopy, elemental analyses, mass spectrometry, molar conductivity, magnetic susceptibility, thermogravimetry, and X-ray diffraction methods, it was determined that the compounds adopt diverse geometries and coordination numbers that range from 4 to 6 as well as different nuclearities. These structural features depend on the choice of the labile groups in the coordination sphere such as chlorides and bromides (mononuclear/tetrahedral), nitrates (mononuclear/tetrahedral or octahedral), and acetates (dinuclear bridged/squared-base pyramid). The ability of the complexes to inhibit carcinoma cells growth was assessed by determining their IC50 values (half-maximum inhibitory concentration) in three different human carcinoma cell lines: HeLa (cervix-uterine), PC3 (prostate), and HCT-15 (colon). It was found that the most active complexes display IC50 values in the range of 160–180 μM. HeLa was found to be the most sensitive cell line towards the treatment, followed by PC3, and HCT-15. The complexes were tested for antimicrobial activity and proved to be non-active against Staphylococcus aureus, Salmonella typhi, Escherichia coli, Micrococcus luteus, and Pseudomonas aeruginosa.

CoII, NiII, CuII, and ZnII complexes of secnidazole adopt diverse geometries and coordination numbers that range from 4 to 6 as well as different nuclearities depending on the choice of the labile groups in the coordination sphere. The complexes are low-to-moderate cytotoxic agents against human carcinoma cells but do not show antimicrobial properties.Figure optionsDownload as PowerPoint slideHighlights
► CoII, NiII, CuII, and ZnII complexes of secnidazole exhibit diverse geometries.
► IC50 values are in the range of 100–400 μM against human carcinoma cell lines.
► Bridging acetates stabilized dinuclear NiII and CuII complexes.