Melatonin protects normal human tissues from the harmful effects of ionizing radiation

Currently, ionizing radiation is used in various fields of human activity, including medicine. However, along with the positive results of medical effects of radiation exposure on the patient's body, there is a need to minimize the negative effects of ionizing radiation. Chemical compounds with radioprotective properties can reduce the damaging effects of ionising radiation on the body, but most of them have disadvantages that limit their use. The work examined the protective properties of melatonin when exposed to gamma radiation on normal human cells. The cells used in the study were human embryonic kidney cells HEK 293. These cells were irradiated with gamma rays at different doses (1, 4, 6, and 10 Gy), and the concentrations of melatonin studied were 0.1, 0.2, and 0.5 mg/ml. The magnitude of manifestation of the properties of melatonin was compared to that of cystamine. The cytotoxicity of melatonin was assessed using the MTT assay. The protective properties of the compound were evaluated by clonogenic analysis and calculation of doubling time. As a result, it was found that melatonin at concentrations of 0.1, 0.2, and 0.5 mg/ml is not toxic to human cells. Melatonin in these concentrations exhibits protective properties, with the most pronounced radioprotective effect observed at a concentration of 0.5 mg/ml. The results indicate the promising and safe use of melatonin as an antioxidant agent due to its absorption of free radicals produced by ionizing radiation, and effective protection against radiation damage.