RESUMO
Objective: To study the radioprotective effect of flavonoids from Ginkgo biloba leaves(GBF). Methods: Three water extracts of GBF were prepared (low dosage 10 mg/100 ml, medium dosage 20 mg/100 ml and high dosage 100 mg/100 ml) and orally administered to mice . After 10 d, the mice were exposed to 8.5Gy -rays. After another 10 d of oral administration, the survival rates were recorded in 30 d. In another experiment, six groups of mice (three GBF groups, radiation control, normal control and cyclophosphamide group) were arranged. The first three groups were orally administered with low, medium and high dosage of GBF respectively for 11d; the other three groups with distilled water. Then the three GBF groups and radiation group were exposed to 1.0Gy -rays. Then they were orally administered again in the following 7d . Micronucleated polychromatic erythrocytes in bone-marrow and sperms (AFS) in mice were observed on the 21st day after termination of oral administration. Proliferation rates of lymphocyte (PRL) were determined in the three GBF groups and normal control. Results: Low, medium and high dosage of GBF increased the survival rates by 31.7%, 25.3% and 26.5% respectively(P