The Effects of Olive Leaf Extract on Antioxidant Enzymes Activity and Tumor Growth in Breast Cancer

Background: Recently, it is suggested that the use of olive leaf polyphenols like oleuropein (OLP), hydroxytyrosol (HT), and others could decrease breast cancer cells viability significantly. Also it has been shown that it inhibits cell proliferation, induces cell apoptosis, reduces cell viability, and significantly stops cell cycle in growth 1 phase (G1) demonstrated via increasing the Michigan Cancer Foundation-7 (MCF- 7) cells in the G0/G1 phase. Objectives: We aimed to study whether the use of olive leaf extract affects breast tumor size and the activity of antioxidant enzymes. Materials and Methods: Four groups of female BALB/c, each containing five mice were studied. Three days after tumor transplantation, the first group received distilled water. The second, third, and fourth groups were treated with 75, 150, and 225 mg/kg/day of olive leaf extract (OLE) for 3 weeks, respectively. To assess anti-cancer and antioxidant effect of OLE, volume and weight of tumor, and also antioxidant enzyme activity were measured. Results: Treatment with 150 and 225 mg/kg/day of OLE reduced the tumor volume and weight (P 0.05) compared to the first group significantly. It also increased the CAT activity (P 0.05) in the third group and increased the activity of superoxide dismutase in the third (P 0.05) and fourth groups (P 0.005) resulted in excitotoxic tolerance in the treatment groups. Conclusions: Consumption of OLE after tumor transplantation reduced the tumor growth. On the other hand, owing to its highly-packed polyphenols, catalase and superoxide dismutase activities in tumor tissue were increased.