THE ANTICLASTOGENICITY OF BETA-CAROTENE EVALUATED ON HUMAN HEPATOMA-CELLS

The efficiency of beta-carotene as a modulatory agent against clastoge nicity induced by cyclophosphamide (CPA), an indirect-acting mutagen, and mitomycin C (MMC), a direct-acting mutagen, was evaluated in human hepatoma cells (Hep G2) using three different treatment regimes. Six doses of beta-carotene, 0.25, 0.5, 1.0, 2.0, 4.0 and 6.0 muM, were tes ted as pre-treatment, simultaneous treatment and pre- + simultaneous t reatment. Since these cells are able to activate mutagens without any exogenous metabolizing system (S9 mix), some problems related to the u se of S9 mix were eliminated. The data obtained show a statistically s ignificant decrease in the frequency of micronuclei (MN) induced by CP A when the cells were treated with beta-carotene, for all treatments, and no effect of this provitamin on the clastogenicity of MMC was foun d. These results reinforce the anticlastogenicity of beta-carotene sho wing that its action is independent of the treatment regime used. On t he other hand, the fact that beta-carotene had a protective action onl y on CPA-induced MN suggests an effect on activation of the promutagen and emphasizes the important utility of cell lines capable of metabol izing chemical mutagens, in such basic studies.