The function of antioxidantsin cells as a protective mechanism during oxidative stress and apoptotic celldeath has been offered. Oxidative stress illustrates an imbalance state betweenthe generation of Reactive oxygen species (ROS) and antioxidant defenses6. ROS are mostly removed by endogenous antioxidants such assuperoxide dismutase (SOD), which converts O2 to H2O2, glutathione peroxidase(GPx) and catalase (CAT) which in turn convert H2O2 to water7. Moreover, exogenous antioxidants including ascorbic acid, ?-tocopherol, ?-carotene,vitamin A prevent excessive generation, of free radicals by combining withthem. Indeed when the redox balance is disrupted, creating an oxidative stress situation8. Treatment of some cancers depends on oxidative stress situation. Severalchemotherapy drugs used in cancer therapy represent their effectiveness by the generationof reactive oxygen species (ROS) and free radicals, which are part of their metabolic activity 9.
Thiosemicarbazone based metal complexesare compounds that possess antitumor, antioxidant, antibacterial, antifungal andantiviral properties10. Antitumor activity of thiosemicarbazones is often linked to the coordination of metal ions 11. Presently, the significant known effects linked to their anticanceractivity are, in order of discovery, ribonucleotide reductase inhibition, generationof reactive oxygen species (ROS), topoisomerase II inhibition, mitochondria disruptionand also multidrug resistance protein (MDR1) inhibition10. Such possible medical activities are owing to the powerful chelatingability of thiosemicarbazones with biologically important metal ions including Ni,Fe, Cu and their reductive capacities Nickel(II) complexes comprising sulphur andnitrogen donor ligands are many significant, since several carbon monoxidedehydrogenases and hydrogenases comprisesuch nickel ion as their active site12.