Abstract
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 (1H-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 μM) 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.Keywords: Omeprazole, 8-Hydroxyquinoline, Mixed-ligand complexes, Alkaline phosphatase, Bidentate bonding behaviors
Highlights
Omeprazole belongs to a class of substituted benzimidazole and has some clinical applications in treatment of peptic-acid diseases like gastric and esophageal ulceration and prevention of their relapse [1]
Low values of conductance measurements suggested the non-electrolyte nature of synthesized mixed ligand metal complexes
The chemical structures of all the synthesized compounds were deduced with the aid of physical and spectroscopic methods
Summary
Omeprazole belongs to a class of substituted benzimidazole and has some clinical applications in treatment of peptic-acid diseases like gastric and esophageal ulceration and prevention of their relapse [1]. All measurements were done in triplicate and the mean of these values was used to calculate the percentage inhibition of ALPs activity The principle of this assay is that colorless pNitrophenyl phosphate (substrate) in alkaline medium changes to a yellow-colored due to liberation of p-Nitrophenol by ALPs. Determination of DPPH radical scavenging activity allowed to attain room temperature. The anti-fungal drug fluconazole and antibacterial drug ampicillin (100 μg/mL) were used as standard controls for comparison with the tested specimens under similar conditions These assays were performed in triplicate, and the mean was taken as the final reading. OMZ, HQL and synthesized mixed ligand metals complexes at various concentrations (500, 250, 125 and 60 μg/mL) were incubated with 3 ml of 0.1 mM DPPH in methanol for 60 min at room temperature. P < 0.05 was taken as indicative of statistical significance
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