Biological efficacy of novel metal complexes of Nitazoxanide: Synthesis, characterization, anti-COVID-19, antioxidant, antibacterial and anticancer activity studies

•Synthesis of three novel metal complexes based nitazoxanide drugs.•Characterization by molar conductance, spectroscopic techniques, as well as thermal analysis.•Geometric optimization using DFT/ B3LYP and quantum parameters investigation.•Biological studies; DNA binding and molecular docking studies.•Several in vitro bioassays were performed to evaluate the biological activity, antibacterial, antioxidant and cytotoxicity activity.•The efficiency of the novel compounds as antivirals was tested by molecular docking with two COVID-19 receptors.