Mechanisms of Cytotoxicity-Inducing Effect of 1,8-cineole, a Plant Terpenoid, on Lepidopteran (Spodoptera frugiperda) Cell Line

Introduction: To the best of our knowledge, there is little information in regards to the cytotoxicity of 1,8- cineole. Insect cells exhibit wide resistance to the lethal effects of chemical compounds. Activation of p53 by acetylation can cause cell toxicity. This study has been carried out in order to investigate whether the use of 1,8-cineole in the Spodoptera frugiperda (SF-9) cell line can induce cytotoxicity by increasing p53 acetylation expression or not. Materials and Methods: SF-9 cell line was cultured in TC100 insect culture medium and treated with 1,8-cineole at concentration of 850.45 μmol/L, based on the half-maximal inhibitory concentration (IC50) index at different times (24, 48, and 72h). The IC50 value was estimated for 1,8-cineole in SF-9. The percentage of alive cells was measured by MTT assay. The ELISA and Bradford protein techniques were used to detect endogenous levels of total and acetylated p53 protein generated in SF-9 cells. Results: The findings of the present study indicated that treatment with 850.45 μmol per liter of 1,8-cineole shows a time-dependent increase in the number of dead cells of SF-9 cell line. The effect of severe toxicity on SF-9 was observed after 72 h of incubation with 1,8-cineole, with approximately 4% of SF-9 cells alive. We observed a significant increase in the level of p53 acetylation up to 48 h in SF-9, indicating that 1,8-cineole resulted in up‑regulation of acetylated P53 and consequently p53 activation in SF-9 cells. Results showed that there is relationship between acetylated p53 protein levels and 1,8-cineole toxicity in SF-9 cell line. Conclusions: 1,8-cineole, may function through common pathways and mediate their cytotoxic effects through targeting p53 and its acetylation in SF-9 cells.