Antimutagenic effect of an antioxidant in mammals

To test a possible antimutagenic activity of ethoxyquin (EQ) in bone-marrow cells, 3 cytogenetic tests with distinct genetic end-points were applied. Cyclophosphamide (CPA), serving as test mutagen, and the antioxidant EQ were administered immediately following each other to Chinese hamsters by stomach tube. Whereas the CPA dose was the same in each test, the EQ doses were increased up to a ratio of CPA/EQ = 1:25, in some cases up to 1:50. The formation of SCEs induced by CPA was not influenced by EQ--even at the highest dose. In the micronucleus test, however, EQ drastically reduced the micronucleus rate even at the lowest dose applied (20 mg/kg) and abolished the CPA effects at a dose of 100 mg/kg. This action of EQ against CPA was also found in the rat and mouse in the micronucleus test system. Two inbred strains of mouse showed similar reactions, but the induced micronucleus rate was higher and its decrease in response to increasing doses of EQ was more delayed. In the chromosome aberration test, EQ also showed a distinct anticlastogenic response. At higher EQ doses, all CPA-induced chromosomal damage was reduced down to the level of spontaneous rates. The anticlastogenic effect of EQ was quantitatively similar in the micronucleus and chromosome aberration tests. Only minor qualitative differences were recognizable.