Open AccessMicrosomal metabolism and activation of the environmental carcinogen 2-amino-3-methyl-9H-pyrido[2,3-b]indole
Author(s) -
Henrik Lauritz Frandsen,
S Damkjaer,
Spiros Grivas,
Ronnie Andersson,
MonaLise Binderup,
John Chr. Larsen
Publication year - 1998
Publication title -
mutagenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 91
eISSN - 1464-3804
pISSN - 0267-8357
DOI - 10.1093/mutage/13.2.181
Subject(s) - chemistry , metabolite , carcinogen , mutagen , metabolism , microsome , indole test , biotransformation , incubation , stereochemistry , nuclear magnetic resonance spectroscopy , biochemistry , chromatography , organic chemistry , enzyme
2-Amino-3-methyl-9H-pyrido[2,3-b]indole (MeA alpha C) is a mutagenic and carcinogenic heterocyclic amine formed as a pyrolysis product during cooking of food and combustion of tobacco. Hepatic microsomes from PCB-induced rats metabolized MeA alpha C to four products, of which three were non-mutagenic and one was mutagenic without S9 activation. The three non-mutagenic products, which accounted for 83% of the metabolism of MeA alpha C, were characterized by mass spectrometry and NMR spectroscopy as 6-hydroxy-MeA alpha C, 7-hydroxy-MeA alpha C and 3-hydroxy-methyl-A alpha C. The mutagenic metabolite, accounting for 17% of the metabolism of MeA alpha C, was characterized as N2-hydroxy-MeA alpha C by comparison with the HPLC retention time and UV spectrum of N2-hydroxy-MeA alpha C obtained by chemical synthesis. N2-Hydroxy-MeA alpha C was very reactive and a part of it bound covalently to microsomal proteins during incubation and a part was degraded to other products during incubation or chromatography. N2-Hydroxy-MeA alpha C was mutagenic in Salmonella typhimurium TA98 without metabolic activation, resulting in 5070 revertants/microgram, which was > 20 times the specific mutagenic activity of the parent compound.