Study on antimutagenicity of the agents related to foods

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1) We had had a theory from the study on flavors that antimutagens must be detected by the rec-assay as well as mutagens. To prove the theory, mutagenicity of over 20 natural food additives were surveyed by Ames test and the rec-assay. They, however, did not show toxicity on the bacteria and so the rec-assay was not useful.2) Several kinds of tea leaves were extracted with boiling water and antimutagenicity of the extracts were surveyed. Japanese tea had strong antimutagenicity but Oolong tea or Puar tea did not have. The experiments of fractionation of the extract with HPLC suggested that antimutagenicity was not due to catekins or caffeins. The extracts showd no toxicity on the bacteria, and the rec-assay was not useful, too.3) We found that the Maillard reactive of alanine and glucose enhanced the mutagenicity of AF-2 and decreased that of MNNG. The mechanism was not cleared.4) Mutagenicity and antimutagenicity of 12 organoarsenic compounds were surveyed. Two of them were positive in the rec-assay and all of them were not mutagenic in Ames assay. Seven induced SCE in CHL cells. Three reduced the mutagenicity of quercetin.5) The mutagenicity of most of typical mutagens decreased strongly by irradiation of a mercury vapour lamp. However, that of 4-nitro-o-phenylenediamine, an intermediate of hair dyes, increased lineally with irradiation.6) We found that the mutagenicity of 1-nitropyrene was enhanced byreducing the concentration of dimethylsulfoxide in the preincubation mixture. The enhancement seemed to be due to increased absorption of the chemicals by the cell walls. This phenomenon were common to the chemicals hardly soluble in water. This experiment suggested a new type of antimutagenicity.