Protective Effects of Origanum onites and Its Components on Lead-Nitrate Induced Genotoxicity in Root Cells of Allium cepa L.

This study investigates the protective effects of components (Thymol; Thy, Carvacrol; Car, Linalool; Lin, and α-Pinene; AP) and essential oil of Origanum onites L. (O. onites-EO), against lead nitrate-induced cytotoxicity and genotoxicity in Allium cepa L. (A. cepa) root tip cells. These components obtained from O. onites were characterized by gas chromatography (GC). A. cepa bulbs were exposed to 6.25-12.5 mg.L-1 concentrations of the O. onites-EO/components of O. onites-EO for analyses of induction of cytogenetic damage. Then, these bulbs were exposed to 10 mg.L-1 concentrations of lead nitrate for analyses of the protective effects of O. onites and its components. Mitotic abnormalities were evaluated for genotoxicity, and mitotic index (MI) for cytotoxicity. As a result of this study, lead nitrate increased the total chromosomal abnormality amount in A. cepa, indicating genotoxicity. MI was decreased with lead nitrate. However, this effect was significantly improved by components of O. onites-EO. This effect was shown with the decrease in the number of chromosomal abnormalities and increase in MI rates in lead nitrate-induced root cells after exposure to the components of O. onites-EO. The protective effect of O. onites-EO components against the damage caused by lead nitrate in cells can be listed as α-Pinene > Thymol > Carvacrol > Linalool. Among all essential oil components tested, α-Pinene was determined to have the strongest protective effect. Furthermore, the protective effect of the essential oil, which contains all the components, could not be determined. It has been observed that the components of essential oil have different effects, and it can be said that these components suppress the effects of each other in the mixture where they are found together. In conclusion, this study shows that the components of O. onites-EO have a protective effect on lead nitrate-induced A. cepa root cells.