Abstract: Purpose : To study the protective effects ofβ-carotene (βC) and vitamin E(V-E) on DNA damages of mice induced by mitomycin C (MMC) . Methods : Forty eight male Kunming mice were divided into 4 groups at random , the mice then were fed with basal diets in normal (A) and positive control (B) groups , basal diet + V-E (200 mg/ kg·bw ,C) , and basal diet + βC (200 mg/ kg·bw , D) for 4 weeks respectively. The mice were injected with MMC (1 mg/ kg·bw) intraperitoneously except for group A which was injected with normal saline before and after 24 h. 12 h later after administration , the mice were killed. The spleen and sternum were excised sterily. The double-stranded DNA remained rate of spleen cells and micronucleus frequency in bone marrow cells were studied. Results : For each group the double- stranded DNA remained rate ( %) was 66. 44 ±5. 97 (A) , 43. 06 ±5. 95 (B) , 58. 69 ±8. 28 (C) , 63. 26 ±7. 95 (D) respectively. The value of group B was significantly lower than those of the others ( P < 0. 01) . Micronuclei ( ‰) in bone marrow cells were 1. 87 ±0. 83 (A) , 31. 00 ±6. 32 (B) , 17. 37 ±2. 88 (C) , 15. 25 ±4. 68 (D) respectively. Group B was significantly higher than those of the others ( P < 0. 01) . Conclusion :βC and V-E can obviously inhibit the DNA breakages of spleen cells and reduce the formation of micronuclei of bone marrow cells in mice induced by MMC.

Key words: β-carotene, vitamin E, mitomycin C, DNA breakage, micronucleus