Evaluation of epigenetic changes of liver tissue induced by oral administration of titanium dioxide nanoparticles and possible protective role of Nigella Sativa oil in adult male albino rats

Objective (s): Titanium dioxide nanoparticles (TiO2 NPs) have been recognized as biologically inert material and have been used in a multitude of applications. Nevertheless, the negative impact on the human health is not yet well understood. The study attempted to evaluate the epigenetic changes of the genome, in the form of DNA methylation in liver tissue samples, resulting from oral administration of TiO2 NPs (mixed rutile and anatase) in adult male albino rats. Furthermore, the preventive activity of the Nigella sativa oil (NSO) on the toxic effects of TiO2 NPs was investigated. Materials and Methods: Thirty-two adult male albino rats were divided into four groups. (I) control, (II) nigella sativa oil, (III) TiO2 NPs and (IV) TiO2 NPs + Nigella sativa oil. The impact of TiO2 NPs on the global DNA methylation and the oxidative status were assessed. Results: Among the study groups, TiO2 NPs exposure provoked oxidative stress; increased blood levels of MDA and decreased reduced glutathione (GSH) level. The global DNA methylation levels decreased after exposure to titanium nanoparticles. Significant differences were recorded between the control group and the group receiving TiO2 NPs. Marked improvement was noticed after supplementation of Nigella sativa oil in terms of DNA methylation and oxidative stress markers. Conclusion: Oral administration of TiO2 NPs caused global DNA hypo-methylation in liver tissue samples. The epigenetic damage raises the concern about the safety associated with applications of the TiO2 NPs. The maintenance of DNA methylation patterns by Nigella sativa oil has a role in protection against genomic instability.