Several known indole compounds are not important precursors of direct mutagenic N-nitroso compounds in green cabbage.
In this study we investigated the role of indole-3-acetonitrile, indole-3-carbinol, indole and tryptophan in the formation of N-nitroso compounds in green cabbage extracts. Green cabbage extracts were separated by gel permeation chromatography. Fractions were treated with nitrite, tested for mutagenicity and analysed for total N-nitroso content. Fractions in which spiked indole-3-acetonitrile, indole-3-carbinol, indole and tryptophan eluted appeared to be low in mutagenic activity and contained relatively small amounts of N-nitroso compounds. To detect indole compounds other than the ones used in the gel permeation chromatography experiments, high-performance liquid chromatography and gas chromatography-mass spectrometry analyses were performed of green cabbage extracts. Indole-3-carboxaldehyde was found to be the most commonly occurring indole compound, but it did not show direct mutagenic activity upon nitrite treatment. Indole-3-acetonitrile was the second most common compound; although it was mutagenic after nitrite treatment, its contribution to the mutagenicity of nitrite-treated green cabbage was roughly estimated to be only 2%. No other indole compounds were detected. From this study we conclude that neither the tested indole compounds nor indole-3-carboxaldehyde play a significant role in the formation of direct mutagenic N-nitroso compounds in nitrite-treated green cabbage extracts.
Tiedink
H G
HG
Agricultural University, Department of Toxicology, Wageningen, The Netherlands.
Hissink
A M
AM
Lodema
S M
SM
van Broekhoven
L W
LW
Jongen
W M
WM
D001937:Brassica / Q000378:metabolism*; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D005961:Glucosinolates / Q000378:metabolism; D007211:Indoles / Q000378:metabolism*; D009153:Mutagens / Q000378:metabolism*; D009603:Nitroso Compounds / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000235:genetics; D014364:Tryptophan / Q000378:metabolism
D005961:Glucosinolates; D007211:Indoles; D009153:Mutagens; D009603:Nitroso Compounds; C030374:indole; D014364:Tryptophan; C016516:indole-3-acetonitrile; C016517:indole-3-carbinol; C048308:glucobrassicin