Antioxidant Activity of Curcumin Protects against the Radiation-Induced Micronuclei Formation in Cultured Human Peripheral Blood Lymphocytes Exposed to Various Doses of γ-Radiation.

PURPOSE: Ionizing radiations trigger the formation of free radicals that damage DNA and cause cell death. DNA damage may be simply evaluated by micronucleus assay and the pharmacophores that impede free radicals could effectively reduce the DNA damage initiated by irradiation. Therefore, it was desired to determine the capacity of curcumin to alleviate micronuclei formation in human peripheral blood lymphocytes (HPBLs) exposed to 0-4 Gy of γ-radiation.

MATERIALS AND METHODS: HPBLs were exposed to 3 Gy after 30 minutes of 0.125, 0.25, 0.5, 1, 2, 5, 10, 20 or 50 µg/mL treatment or with 0.5 μg/mL curcumin 30 minutes early to 0, 0.5, 1, 2, 3 or 4 Gy 60 Co γ-irradiation. Cytokinesis of HPBLs was blocked by cytochalasin B and micronuclei scored. The ability of curcumin to suppress free radical induction in vitro was determined by standard methods.

RESULTS: HPBLs treated with different concentrations of curcumin before 3 Gy irradiation alleviated the micronuclei formation depending on curcumin concentration and the lowest micronuclei were detected at 0.5 µg/mL curcumin when compared to 3 Gy irradiation alone. Increasing curcumin concentration caused a gradual rise in micronuclei, and the significant increases were detected at 10 to 50 µg/mL curcumin than 3 Gy irradiation alone. Irradiation of HPBLs to different doses of γ-rays caused a significant rise in micronuclei depending on radiation dose, whereas HPBLs treated with 0.5 µg/mL curcumin 30 minutes before irradiation to different doses of γ-rays significantly reduced frequencies of HPBLs with one, two, or more micronuclei. Curcumin treatment inhibited the formation of hydroxyl (OH), 2,2-azinobis(3-ethylbenzo- thiazoline-6-sulfonic acid) (ABTS), 2,2'-diphenyl-1-picrylhydrazyl (DPPH), and (nitric oxide) NO free radicals in a concentration-related way.

CONCLUSIONS: Curcumin when treated at a dose of 0.5 μg/mL attenuated micronuclei formation after γ-irradiation by inhibiting the formation of radiation-induced free radicals.