Inhibition of Colorectal Cancer Cell Line CaCo-2 by Essential Oil of Eucalyptus camaldulensis Through Induction of Apoptosis

Treatment of colorectal cancer is one of the important challenges due to the increase of resistance to chemotherapeutic drugs. Isolated natural compounds from medicinal plants and other sources often are used as novel drugs for treatment of various human cancer. The aim of this study was to investigate the antioxidant and anticancer activity of Eucalyptus camaldulensis essential oil on colorectal cancer cell line Caco-2. The antioxidant activity of extracted E. camaldulensis essential oil (1000, 800, 400, 200, 100, 50, 25, 12.5, 6, and 3 μg/mL) was evaluated by free radicals inactivation method. Moreover, MTT assay was used to examine the cytotoxic effects of E. camaldulensis essential oil on the Caco-2 cell line. The mRNA expression of BAX and BCL-2 genes was studied using quantitative Real-Time PCR method, in treated cancer cells compared to untreated cells. We indicated a significant, impressive antioxidant activity in 1000 μg/mL of E. camaldulensis essential oil, in a concentration-dependent manner. In addition, we found that this product exerted a cytotoxic effect on cancer cells when 100 μg/mL concentration was considered as half-maximal inhibitory concentration (IC50). Also, the expression of BAX and BCL-2 genes were significantly upregulated and downregulated, respectively, in the treated Caco-2 cells with E. camaldulensis essential oil. In conclusion, our study showed significant antioxidant and anticancer activity in E. camaldulensis essential oil in a concentration and time-dependent manner, which may be due to the reduction of free radicals and induction of apoptosis process in colorectal cancer cells.