Antioxidant vitamins C, E and beta-carotene reduce DNA damage before as well as after gamma-ray irradiation of human lymphocytes in vitro

The protective effect of Vitamins C, E and beta-carotene against gamma-ray-induced DNA damage in human lymphocytes in vitro was investigated. Cultured lymphocytes were exposed to increasing concentration of these vitamins either before or after irradiation with 2Gy of gamma-rays and DNA damage was estimated using micronucleus assay. A radioprotective effect was observed when antioxidant vitamins were added to cultured cells before as well after irradiation; the strongest effect was observed when they were added no later than 1h after irradiation. The radioprotective effect of vitamins also depended on their concentration; Vitamins C added at low concentration (1 microg/ml) before exposure of the cells to radiation prevented induction of micronuclei. Vitamin E at the concentration above 2 microg/ml decreased the level of radiation-induced micronuclei when compared to the cells irradiated without vitamin treatment. beta-Carotene was effective at all tested concentrations from 1 to 5 microg/ml and reduced the number of micronuclei in irradiated cells. The vitamins had no effect on radiation-induced cytotoxicity as measured by nuclear division index. The radioprotective action of antioxidant Vitamins C, E and beta-carotene was dependent upon their concentration as well as time and sequence of application.