Reaction of the N2-acetoxy derivative of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) with 2'-deoxyguanosine and DNA. Synthesis and identification of N2-(2'-deoxyguanosin-8-yl)-PhIP.
The direct acting mutagenic N2-hydroxylated metabolite of the food mutagen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) does not react with DNA. Upon acetylation of the N2-hydroxy-PhIP with acetic anhydride two products could be detected. Mass spectrometric analysis showed that both products were monoacetyl derivatives of N2-hydroxy-PhIP. One of the products did not show any reactivity towards DNA and is probably the N-acetyl derivative of N2-hydroxy-PhIP. The other product which is most likely to be N2-acetoxy-PhIP reacted with DNA and 2'-deoxyguanosine but not with 2'-deoxycytidine, 2'-deoxyadenosine or 2'-deoxythymidine. The PhIP-2'-deoxyguanosine adduct was purified and characterized by mass spectral, 1H and [13C]NMR analysis, showing that PhIP like the other cooked food mutagen 2-amino-3-methylimidazo[4,5-f]quinoline, had reacted with C-8 of guanine forming N2-(2'-deoxyguanosin-8-yl)-PhIP. HPLC analysis of enzymatically hydrolyzed calf thymus DNA which had been reacted with N2-acetoxy-PhIP showed one adduct which was chromatographically and spectroscopically identical to N2-(2'-deoxyguanosin-8-yl)-PhIP. HPLC separation followed by liquid scintillation counting of hydrolyzed liver DNA from a rat dosed with [3H]PhIP showed that radioactivity coeluted with the hydrolysis product of the synthetic PhIP-2-deoxyguanosine adduct, indicating that PhIP in vivo also forms an N2-(2'-deoxyguanosin-8-yl)-PhIP adduct.
Frandsen
H
H
Institute of Toxicology, National Food Agency, Søborg, Denmark.
Grivas
S
S
Andersson
R
R
Dragsted
L
L
Larsen
J C
JC
D000818:Animals; D004247:DNA / Q000378:metabolism*; D003849:Deoxyguanosine / Q000378:metabolism*; D007093:Imidazoles / Q000378:metabolism*; D008297:Male; D009153:Mutagens / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D007093:Imidazoles; D009153:Mutagens; D004247:DNA; C049584:2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine; D003849:Deoxyguanosine