Synthesis, characterization, and 32p-postlabeling analysis of DNA adducts derived from the environmental contaminant 3-nitrobenzanthrone.
3-Nitrobenzanthrone (3-NBA) is a potent mutagen and potential human carcinogen identified in diesel exhaust and ambient air particulate matter. 3-NBA forms DNA adducts in rodent tissues that arise principally through reduction to N-hydroxy-3-aminobenzanthrone (N-OH-ABA), esterification to its acetate or sulfate ester, and reaction of this activated ester with DNA. We detected 3-NBA-derived DNA adducts in rodent tissues by (32)P-postlabeling and generated them chemically by acid-catalyzed reaction of N-OH-ABA with DNA, but their structural identification has not yet been reported. We have now prepared 3-NBA-derived adducts by reaction of a possible reactive metabolite, N-acetoxy-N-acetyl-3-aminobenzanthrone (N-Aco-N-Ac-ABA), with purine nucleosides and nucleotides, characterized them, and have shown that they are present in DNA treated with this 3-NBA derivative. Three of these adducts have been characterized as the C-C adduct N-acetyl-3-amino-2-(2'-deoxyguanosin-8-yl)benzanthrone, the C-N adduct N-acetyl-N-(2'-deoxyguanosin-8-yl)-3-aminobenzanthrone, and an unusual 3-acetylaminobenzanthrone adduct of deoxyadenosine, which involves a double linkage between adenine and benzanthrone (N1 to C1, N(6) to C11b), creating a five-membered imidazo type ring system. According to IUPAC fused ring conventions, we propose the following systematic name for this adduct: (9'-(2' '-deoxyribofuranosyl))purino[6',1':2,3]imidazo[5,4-p](1,11b-dihydro-(N-acetyl-3-amino))benzanthrone. The 3'-phosphates of these novel adducts could be 5'-postlabeled using [gamma-(32)P]ATP, although the efficiency of labeling was found to be low (less than 20%). However, none of these adducts could be detected in DNA from 3-NBA-treated rats by (32)P-postlabeling. Two of these synthetic adducts were treated with alkali to generate nonacetylated adducts, and these were also shown by HPLC to differ from those adducts found in rat DNA. Therefore, a different approach to the synthesis of authentic standards is needed for the structural characterization of 3-NBA-derived DNA adducts formed in vivo.
Osborne
Martin R
MR
Section of Molecular Carcinogenesis and Cancer Research UK Centre for Cancer Therapeutics, Institute of Cancer Research, Brookes Lawley Building, Cotswold Road, Sutton, Surrey SM2 5NG, United Kingdom.
Arlt
Volker M
VM
Kliem
Christian
C
Hull
William E
WE
Mirza
Amin
A
Bieler
Christian A
CA
Schmeiser
Heinz H
HH
Phillips
David H
DH
D000818:Animals; D001551:Benz(a)Anthracenes / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D018736:DNA Adducts / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D004249:DNA Damage; D004785:Environmental Pollutants / Q000378:metabolism / Q000633:toxicity*; D005260:Female; D015394:Molecular Structure; D010761:Phosphorus Radioisotopes; D051381:Rats; D017208:Rats, Wistar
D001551:Benz(a)Anthracenes; D018736:DNA Adducts; D004785:Environmental Pollutants; D010761:Phosphorus Radioisotopes; D004247:DNA; C117220:3-nitrobenzanthrone