Journal of Lipid Research, Vol 25, 523-526, Copyright © 1984 by Lipid Research, Inc.
A method for measurement of nanogram quantities of 3-methylcholanthrene in stool samples
WC Duane, JC Behrens, SG Kelly and AS Levine
The carcinogen 3-methylcholanthrene can be produced from deoxycholic acid
and is postulated by some investigators to play a role in the pathogenesis
of colon carcinoma. The small quantities of this compound which could be
carcinogenic have been difficult to measure in feces because of many
potentially interfering compounds. Using 3-[6- 14C]methylcholanthrene as an
internal standard, petroleum ether extraction, C-18 SepPak separation,
preparative high performance liquid chromatography, and gas-liquid
chromatography-mass spectrometry with selected ion monitoring, we developed
an assay capable of detecting less than 35 ng of 3-methylcholanthrene per
gram of stool. Application of this technique to stools of five patients
with colon carcinoma and two normal controls revealed no detectable
3-methylcholanthrene in any stool sample. This negative result was
confirmed by incubating radiolabeled cholic acid in fecal homogenates.
Although greater than 90% of this radiolabeled bile acid was converted to
deoxycholic acid, none of the radioactivity was found in the thin-layer
chromatography fraction corresponding to 3-methylcholanthrene. These
observations provide evidence against a role for 3-methylcholanthrene in
pathogenesis of human colon carcinoma. Similar assays could be used for
analysis of other carcinogens in stool samples.
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