Genistein treatment protects mice from ionizing radiation injury.

The radioprotective and behavioral effects of an acute administration of the isoflavone genistein (4',5,7-trihydroxyflavone) were investigated in adult CD2F1 male mice. Mice were administered a single subcutaneous (s.c.) dose of genistein either 24 h or 1 h before a lethal dose of gamma radiation (9.5-Gy of cobalt-60 at 0.6 Gy min(-1)). Mice received saline, PEG-400 vehicle or genistein at 3.125, 6.25, 12.5, 25, 50, 100, 200, or 400 mg kg(-1) body weight. For mice treated 24 h before irradiation there was a significant increase in 30-day survival for animals receiving genistein doses of 25 to 400 mg kg(-1) (p<0.001). In contrast, the 30-day survival rates of mice treated with genistein 1 h before irradiation were not significantly different from those of the vehicle control group. Additionally, the acute toxicity of genistein was evaluated in non-irradiated male mice administered a single s.c. injection of saline, vehicle, or genistein at 100, 200 or 400 mg kg(-1). At these genistein doses there were no adverse effects, compared with controls, on locomotor activity, grip strength, motor coordination, body weight, testes weight, or histopathology. These results demonstrate that a single s.c. administration of the flavonoid genistein at non-toxic doses provides protection against acute radiation injury.