In vitro formation and degradation of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) protein adducts. 1994

R Reistad, and H Frandsen, and S Grivas, and J Alexander
National Institute for Consumer Research, Lysaker, Norway.

Adduct formation between the food mutagen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and rat serum albumin (RSA) was studied in vitro using hepatic microsomes isolated from polychlorinated biphenyl-induced rats. With 1-methyl-2-nitro-6-phenylimidazo[4,5-b]pyridine (2-nitro-PhIP) as starting material, four main products were formed. Pretreatment of RSA with beta-mercaptoethanol markedly increased the yield of one of them. In this adduct, the C-2 of PhIP was linked to cysteine of RSA at position 34 in a C-S linkage. With N2-acetoxy-PhIP as starting material, unstable conjugates were formed with RSA as well as with glutathione (GSH) and cysteine. The suggested structures of the GSH and cysteine conjugates, GSH-S-N2-PhIP and cysteine-S-N2-PhIP respectively, are based on mass spectra and UV spectra. The degradation of the conjugates of GSH and cysteine as well as of the protein adduct were monitored. They all resulted in the same degradation product, identified as 2-amino-5-hydroxy-1-methyl-6-phenylimidazo[4,5-b]pyridine (5-hydroxy-PhIP).

UI MeSH Term Description Entries
D007093 Imidazoles Compounds containing 1,3-diazole, a five membered aromatic ring containing two nitrogen atoms separated by one of the carbons. Chemically reduced ones include IMIDAZOLINES and IMIDAZOLIDINES. Distinguish from 1,2-diazole (PYRAZOLES).
D009153 Mutagens Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes. Clastogen,Clastogens,Genotoxin,Genotoxins,Mutagen
D002273 Carcinogens Substances that increase the risk of NEOPLASMS in humans or animals. Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included. Carcinogen,Oncogen,Oncogens,Tumor Initiator,Tumor Initiators,Tumor Promoter,Tumor Promoters,Initiator, Tumor,Initiators, Tumor,Promoter, Tumor,Promoters, Tumor
D003545 Cysteine A thiol-containing non-essential amino acid that is oxidized to form CYSTINE. Cysteine Hydrochloride,Half-Cystine,L-Cysteine,Zinc Cysteinate,Half Cystine,L Cysteine
D005978 Glutathione A tripeptide with many roles in cells. It conjugates to drugs to make them more soluble for excretion, is a cofactor for some enzymes, is involved in protein disulfide bond rearrangement and reduces peroxides. Reduced Glutathione,gamma-L-Glu-L-Cys-Gly,gamma-L-Glutamyl-L-Cysteinylglycine,Glutathione, Reduced,gamma L Glu L Cys Gly,gamma L Glutamyl L Cysteinylglycine
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012709 Serum Albumin A major protein in the BLOOD. It is important in maintaining the colloidal osmotic pressure and transporting large organic molecules. Plasma Albumin,Albumin, Serum
D051381 Rats The common name for the genus Rattus. Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus

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