4-Methoxyindole derivatives as nitrosable precursors of mutagens in Chinese cabbage

Two indole compounds isolated from fresh Chinese cabbage were shown to be mutagen precursors that yielded direct-acting mutagens on treatment with nitrite. They were identified as 4-methoxyindole-3-acetonitrile and 4-methoxy-indole-3-aldehyde. When these compounds were treated with 50 mM nitrite at pH 3.0 for 1 h at 37 degrees C, 4-methoxyindole-3-acetonitrile induced 31,800 and 10,000 revertants of Salmonella typhimurium TA100 and TA98, respectively, per mg of mutagen precursor in the absence of S9 mix, and 4-methoxyindole-3-aldehyde induced 156,900 revertants of TA100 and 26,800 revertants of TA98 per mg in the absence of S9 mix.