Synthesis, characterization and pharmacological evaluation of mixed ligand-metal complexes containing omeprazole and 8-hydroxyquinoline

Purpose: To synthesize a series of mixed ligand-metal complexes and to evaluate their alkaline phosphatase inhibitory capacities, antioxidant potential and antimicrobial activities. Method: Mixed ligand-metal complexes of Zn (II), Ni (II), Co (II), Cu (II), omeprazole and 8-hydroxyquinoline were synthesized. The ligand-metal complexes were characterized by various physicochemical techniques, including elemental analysis, magnetic susceptibility, scanning electron microscope (SEM), mass spectrometry (EI-MS), ultraviolet-visible (UV-Vis) spectrophotometry, Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (H-1-NMR) and conductance studies. The new compounds were also investigated for their alkaline phosphatase (ALPs) inhibition, 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging and antimicrobial activities. Results: Spectroscopic studies revealed the chemical composition of synthesized compounds as well as the bidentate bonding behavior of the coordinating ligands with metal ions. Conductance measurement suggested that the metal complexes were non-electrolytes. Ni(II) complex exhibited antioxidant activity (30.48 +/- 0.32 mu M) higher than those of BHT (standard) and other complexes. Stronger inhibition of ALPs by Ni (II) mixed ligand complex compared to the other complexes was evident. The synthesized compounds showed moderate to very good antimicrobial activity against bacterial strains, i.e., Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Actinomyces viscosus, Staphylococcus aureus, Bacillus subtilis; as well as against the fungal strains, Candida albicans, Aspergillus flavus and Aspergillus niger. Conclusion: All the mixed ligand complexes demonstrate higher antioxidant, ALPs-inhibitory and antimicrobial activities than their corresponding ligands. This indicates their therapeutic potential as future drug candidates for the concerned diseases.