The protective effect of oleuropein against radiation-induced cytotoxicity, apoptosis and genetic damage in cultured human lymphocytes.
Int J Radiat Biol. 2020 Sep 24:1-34. Epub 2020 Sep 24. PMID: 32970517
Oleuropein is one of the most abundant and important phenolic compounds in fruits and olive leaves . In this research, the radioprotective effect of oleuropein was investigated versus 2 Gy of gamma radiation on human peripheral blood mononuclear cells. The aim of this study was to evaluate the effects of oleuropein radiation protection and to find an effective radioprotector.Human mononuclear cells were treated with oleuropein at the concentration of 100 μM (optimum concentration), incubated for 24 hours, and then exposed to 2Gy gamma rays. The anti-radiation effect of oleuropein was assessed by MTT assay, flow cytometry, comet assay, and micronucleus (MN) assay.It was found that pre-treatment with oleuropein (25, 50, 75, 100, 200, 400, and 800 nM -1, 5, 10, 15, 20, 25, 30, 40, 50, 75, 100, 125, 150, 175, 200 µM) significantly increased the percentage of cell viability compared to the irradiated group (p < 0.001) . Moreover, oleuropein treatment with the above concentrations defined without γ-ray did not show any cytotoxicity effect in human mononuclear cells . The LDdose was calculated as 2.9 Gy, whereas by 200, 150, 50, and 100 µM oleuropein prior to radiation (1, 2,and 4 Gy) , radiation LDincreased to 3.36, 3.54, 3.81, and greater than 4 Gy, in that order. A very noticeable dose-modifying factor (DMF) of 1.16, 1.23, 1.31, and 1.72 was observed for 200, 150, 50, and 100µM, in order . Therefore, 100 µM of oleuropein was selected as the desirable dose for radio-protection trial, and 2 Gy gamma rays were used for further research. Human mononuclear cells treatment with oleuropein (100 µM) prior to 2Gy gamma rays significantly decreased apoptosis, genomic damage, and MN occurrence in human mononuclear caused by γ-radiation (p < 0.001) . Further more, treatment with oleuropein (100 µM) without radiation did not lead to apoptosis, genotoxicity, or clastogenic effects caused by oleuropein in human mononuclear cells.The results revealed that oleuropein is able to significantly reduce cytotoxicity, apoptosis, genotoxic, and clastogenic effects of gamma rays.