Oxidative stress contributes to cobalt oxide nanoparticles-induced cytotoxicity and DNA damage in human hepatocarcinoma cells

Saud Alarifi,1 Daoud Ali,1 Al Omar Suliman Y,2 Maqusood Ahamed,3 Maqsood A Siddiqui,2 Abdulaziz A Al-Khedhairy21Cell and Molecular Laboratory, Department of Zoology, Faculty of Science, King Saud University, Riyadh, Saudi Arabia; 2Faculty of Science, Department of Zoology, King Saud University, Riyadh, Saudi Arabia; 3King Abdullah Institute for Nanotechnology, King Saud University, Riyadh, Saudi ArabiaBackground: Cobalt oxide nanoparticles (Co3O4NPs) are increasingly recognized for their utility in biological applications, magnetic resonance imaging, and drug delivery. However, little is known about the toxicity of Co3O4NPs in human cells.Methods: We investigated the possible mechanisms of genotoxicity induced by Co3O4NPs in human hepatocarcinoma (HepG2) cells. Cell viability, reactive oxygen species (ROS), glutathione, thiobarbituric acid reactive substance, apoptosis, and DNA damage were assessed in HepG2 cells after Co3O4NPs and Co2+ exposure.Results: Co3O4NPs elicited a significant (P < 0.01) reduction in glutathione with a concomitant increase in lipid hydroperoxide, ROS generation, superoxide dismutase, and catalase activity after 24- and 48-hour exposure. Co3O4NPs had a mild cytotoxic effect in HepG2 cells; however, it induced ROS and oxidative stress, leading to DNA damage, a probable mechanism of genotoxicity. The comet assay showed a statistically significant (P < 0.01) dose- and time-related increase in DNA damage for Co3O4NPs, whereas Co2+ induced less change than Co3O4NPs but significantly more than control.Conclusion: Our results demonstrated that Co3O4NPs induced cytotoxicity and genotoxicity in HepG2 cells through ROS and oxidative stress.Keywords: cobalt oxide nanoparticles, HepG2 cells, cytotoxicity, oxidative stress, DNA damage