Cytotoxicity of the MEIC reference chemicals in antioxidant-enriched rat hepatoma-derived Fa32 cells

Since vitamin E increases the antioxidant status of cells, its influence on cytotoxicity was investigated. The neutral red uptake (NRU) inhibition eff ects of 39 MEIC reference chemicals were measured after treatment of rat he patoma-derived Fa32 cells in the presence of vitamin E for 30 minutes. The results were quantified in terms of the NI50, the concentration of test com pound required to reduce the NRU by 50%. Sodium chloride was the only chemi cal that was more toxic in the presence of vitamin E. This effect was relat ed to the concentration of vitamin E in the cell culture medium. A vitamin E dose-related response was also observed for the decreased toxicity of par acetamol and caffeine. Glutathione levels were slightly increased in the pr esence of vitamin E, which could contribute to the protective effect of vit amin E. Of the remaining chemicals, 50% were less toxic in the presence of vitamin E, but the correlation with the acute human toxicity data of the ME IC study was not improved. The results imply that reactive oxygen species i nterfere with the toxicity of a high proportion of toxic chemicals. The ass ay described provides a quick and easy method for checking whether reactive oxygen species contribute to the toxicity of a chemical.