Synthesis, characterization and antibacterial study of Co(II) and Cu(II) complexes of mixed ligands of piperaquine and diclofenac

Abstract

Pathogenic microorganisms develop incessant resistance toward antibiotics through various cellular defense mechanisms, thereby creating a search for chemotherapeutic alternatives, the potentials of which metal complexes of small-molecule drugs offer. In this study, Cu(II) and Co(II) complexes of mixed piperaquine and diclofenac were synthesized and characterized via magnetic moment determination, elemental analysis, FTIR, UV-Visible, 1D 1H NMR, 13C NMR spectroscopy and powder XRD, then evaluated for biological activities in silico and in vitro. The results provide evidence of coordination of the metal ions to ligands through N, COO and Cl groups with proposed octahedral geometry, low spin, paramagnetic, polycrystalline complexes. The physicochemical and pharmacokinetic parameters predicted in silico support bio-functionality and safety of the complexes. The complexes demonstrate strong inhibition against bacterial strains especially Staphylococcus aureus in vitro. Specifically, Cu(II) complex at 1% w/w inhibited a zone of 100 mm which is in multi-folds of the effects of piperaquine and diclofenac with 32 and 25 mm respectively, and better than ciprofloxacin with 92 mm. On DPPH assay, both complexes display better antioxidant potentials with respective IC50 of 165.09 and 382.7 µg/mL compared to ascorbic acid with 7526 µg/mL. Thus, the complexes represent therapeutic models for overcoming antibacterial resistance upon further study.