Refashioning of the drug-properties of fluoroquinolone through the synthesis of a levofloxacin-imidazole cobalt (II) complex and its interaction studies on with DNA and BSA biopolymers, antimicrobial and cytotoxic studies on breast cancer cell lines

Abstract

Levofloxacin (HLVX), a quinolone antimicrobial agent, when deprotonated (LVX^-) behaves as a bidentate ligand, and it coordinates to Co²⁺ through the pyridone oxygen and the carboxylate oxygen. Along with two imidazole (ImH) ligands, levofloxacin forms a Co(II)-Levofloxacin-imidazole complex, [CoCl(LVX)(ImH)₂(H₂O)]·3H₂O (abbreviated henceforth as CoLevim) which was isolated and characterized by ¹H and ¹³C NMR spectroscopy, UV-visible and FT-IR spectroscopy, powder X-ray diffraction and thermal analysis methods. CoLevim shows promise in its antimicrobial activities when tested against microorganisms (Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Staphylococcus aureus, Salmonella typhimurium and Escherichia coli). Fluorescence competitive studies with ethidium bromide (EB) revealed that CoLevim can compete with EB and displace it to bind to CT-DNA through intercalative binding mode. In addition, CoLevim exhibited a good binding propensity to BSA proteins with relatively high binding constants. The antioxidant activities of the free ligands and CoLevim were determined in vitro using ABTS⁺ radical (TEAC assay). The Co-complex showed a better antioxidant capacity with inhibitory concentrations (IC₅₀) of 40 μM than the free ligands. CoLevim also showed noteworthy apoptotic potential and behaved as an efficient resistant modifying agent when its antiproliferative potential was examined by MTT assay using the breast cancer cell lines (MCF7, MCF7Dox/R and MCF7Pacli/R cells).

Keywords: Antibacterial activity; Antioxidant; Breast cancer cell line MCF 7; Fluoroquinolone; Imidazole; Intercalation; Levofloxacin.