Abstract: OBJECTIVE: To study the protection of Flastem milkvetch seed extract (FMSE) on the genetic damage of bone marrow lymphocyte induced by mitomycin C (MMC) in mice. METHODS：100 Kunming mice were divided into 5 groups at random，normal saline in control group and 2 mg/kg MMC were taken model groups. FMSE 20，40 and 80 mg/ (kg•d) were given daily in the low， medium and high dose groups for 10 d. 12 hours before the last gastric gavage，the mice received intraperitoneal MMC (2 mg/kg) except for normal group which received NS. Then the mice were killed by cervical dislocation. The bone marrow lymphocytes suspension was prepared. Comets electrophoresis， formation of micronucleus of polychromatic erythroblasts (PCE)， chromosome aberration test in bone marrow lymphocytes of mice and mitotic index (MI) were determined to study the protection of FMSE on the genetic damage of bone marrow lymphocytes induced by MMC. RESULTS：After using MMC alone in model group， rates of tailing，tail length，micronucleus and chromosome aberration of the bone marrow lymphocytes were significantly enhanced (P<0.01) compared with those of normal group. Meanwhile MI of model group was significantly lower than that of normal group (P<0.01). After using different concentrations of high， medium and low FMSE combined with intrapertioneal MMC， rates of tailing，tail length，micronucleus and chromosome aberration of the bone marrow lymphocytes were significantly decreased compared with those of control group (P<0.01) . MI of model group was dramatically higher than that of normal group (P<0.01). CONCLUSION：FMSE could significantly protect the genetic damage of bone marrow lymphocytes induced by MMC in mice.

Key words: Flastem milkvetch seed extract, mitomycin C, DNA injury, mitotic index, chromosome aberration, micronucleus