Improvement of the antioxidant activity of thyme essential oil against biosynthesized titanium dioxide nanoparticles-induced oxidative stress, DNA damage, and disturbances in gene expression in vivo.

Background: Titanium dioxide nanoparticles (TiO ₂ -NPs) are widely utilized in medicine and industry; however, their safety in biological organisms is still unclear. In this study, we determined the bioactive constitutes of thyme essential oil (TEO) and utilized the nanoemulsion technique to improve its protective efficiency against oxidative stress, genotoxicity, and DNA damage of biosynthesized titanium dioxide nanoparticles (TiO ₂ -NPs).
Methods: TEO nanoemulsion (TEON) was prepared using whey protein isolate (WPI). Sixty male Sprague-Dawley rats were divided into six groups and treated orally for 21 days including the control group, TEO, or TEON- treated groups (5 mg/kg b.w), TiO ₂ -NPs-treated group (50 mg/kg b.w) and the groups received TiO ₂ -NPs plus TEO or TEON. Blood and tissues samples were collected for different assays.
Results: The GC-MS analysis identified 17 bioactive compounds in TEO and thymol and carvacrol were the major compounds. TEON was irregular with average particles size of 230 ± 3.7 nm and ζ-potential of -24.17 mV. However, TiO2-NPs showed a polygonal shape with an average size of 50 ± 2.4 nm and ζ-potential of -30.44 mV. Animals that received TiO2-NPs showed severe disturbances in liver and kidney indices, lipid profile, oxidant/antioxidant indices, inflammatory cytokines, gene expressions, increased DNA damage, and pathological changes in hepatic tissue. Both TEO and TEON showed potential protection against these hazards and TEON was more effective than TEO.
Conclusion: The nanoemulsion of TEO enhances the oil bioactivity, improves its antioxidant characteristics, and protects against oxidative damage and genotoxicity of TiO2-NPs.
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