Modulating effects of melatonin, vitamin C and saffron alone or in combination on radiation induced cell lethality; an in vitro study with Hela cells

Introduction: Radiation countermeasures are defined as use of an agent to minimize the deleterious effects of radiation therapy by administering the compound after the radiation exposure has occurred, regardless of toxicity. In spite of extensive study in this field, yet there is no suitable radioprotector introduced. In this study two naturally occurring antioxidants were studied on radiation induced cell lethality. Materials and Methods: Various doses of melatonin, saffron and vitamin C were examined for their antioxidant capacity by using DPPH test. Hela cells were treated with optimum doses of melatonin, saffron and vitamin C; ۲ hours prior to gamma irradiation alone or in combination. Treated cells were irradiated with various doses of gamma rays (۲, ۴, ۸ Gy), then cells were plated in ۹۶ well plates for MTT assay. Cells were fixed at ۴۸ and ۷۲ hours after plating and reading was done ELISA reader. Results: Results showed cell viability reduced slightly after ۴۸ h irradiation. Pretreatment of cells with melatonin and vitamin C increased cell lethality considerably for dopses of ۲ and ۴ Gy, but surprisingly presence of melatonine and vitamin C led to an increase in cell viability when combined with ۸ Gy gamma rays. Combination of these agents with saffron showed similar effects. Similar results were observed for ۷۲ h sampling time. However, protective effect of these agents was more pronounced when using ۸ Gy radiation dose. Conclusion: Results indicate that despite the antioxidant potential of melatonin, saffron and vitamin C, when combined with low and moderate doses of gamma rays (۲ and ۴ Gy) led to increased cytotoxic effects of ionizing radiation. However, at high dose of gamma rays (۸ Gy) radioprotective effect was seen. The dual action of these agents with low and high doses of ionizing radiation is not known.