Mutagenicity, comutagenicity, and antimutagenicity of erythrosine (FD and C red 3), a food dye, in the Ames/Salmonella assay

Erythrosine (diNa, tetraiodofluorescein) was nonmutagenic to the Ames/Salmonella typhimurium strains TA97a, TA98, TA100, TA102, and TA104, to a concentration of 2 mg/plate. No mutative intermediates were detected on metabolism by rat caecal cell-free extracts or rat liver S9 mixture; or on incubation with the comutagens, harman and norharman (+/- S9). Instead, an unexpected dose-dependent suppression in spontaneous reversion frequencies was observed (maximum approximately equal to 35% decrease). Erythrosine was antimutagenic to benzo[a]pyrene, but it did not decrease the mutagenicity of the other adduct-forming mutagen, 4-nitroquinoline N-oxide. The food dye was strongly antimutagenic to the bifunctional alkylating agent, mitomycin C, though it did not exhibit a similar effect on the mutagenicity of the corresponding monofunctional agent, methyl methanesulphonate. It partially depressed the mutagenic potentials of sodium azide. The antimutagenic effect of erythrosine on an intercalating agent, ethidium bromide, was discernible only at the highest dose (2 mg/plate). These results have been interpreted in terms of a genointeractive role of erythrosine. Erythrosine produced differential toxic effects in repair-deficient (TA97a, TA98, TA100) and repair-proficient (TA102, TA104) Salmonella tester strains; survival of the repair-deficient strains was found to be decreased. Photoinduced potentiation of erythrosine toxicity was observed, although light irradiation in the presence of erythrosine did not modify the reversion frequencies of the tester strains. The evidence strongly suggests that erythrosine, which exhibits nonmutagenicity in the Ames/Salmonella test, can interact with DNA repair enzymes and/or with DNA.