Characterization of DNA adducts at the bay region of dibenz[a,h]anthracene formed in vitro.
Bay region diolepoxide-DNA adducts of dibenz[a,h]anthracene (DBA) formed in vitro were identified and their absolute stereochemistry was assigned. After activation of [5,12-14C]DBA with liver microsomes obtained from Aroclor 1254 treated male Sprague-Dawley rats in the presence of calf thymus DNA for 1 h, the amount of DNA adducts was found to be 9.9 +/- 2.4 pmol/mg DNA, calculated on the basis of the portion of radioactivity eluted from the HPLC reversed-phase column with a water/acetonitrile gradient. Bay region diolepoxide-DNA adducts represented 27.5% of radioactivity associated with DNA adducts. The absolute configuration of the various adducts was determined from the reaction of the (+)- and (-)-3,4-dihydrodiol after metabolic activation and the reaction of the anti- and syn-3,4-dihydroxy-1,2-epoxy-1,2,3,4-tetrahydrodibenz[a,h]anthracen e with DNA or with the individual deoxyribonucleotides. The main bay region adduct was identified as a deoxyguanosine adduct of (anti)-3S,4R-dihydroxy-1R,2S-epoxy-1,2,3,4-tetrahydrodibenz [a,h]anthracene, a metabolite of (-)-3,4-dihydroxy-3,4-dihydrodi- benz[a,h]anthracene. Anti bay region diolepoxide-deoxyguanosine adducts of DBA contributed to 17.7% and syn diolepoxide-derived deoxyguanosine adducts to 5.8% of adduct-associated radioactivity. The amount of bay region deoxyadenosine adducts was calculated to be 4%. For six of probably eight different deoxyadenosine adducts absolute stereochemistry could be assigned. 32P-Postlabelling experiments revealed a binding of 23 +/- 6 pmol/mg DNA for (-)-3,4-dihydrodiol and of 1.5 +/- 0.4 pmol/mg DNA for (+)-3,4-dihydrodiol of DBA.
Mlcoch
J
J
Institute of Toxicology, University of Mainz, Germany.
Fuchs
J
J
Oesch
F
F
Platt
K L
KL
D000818:Animals; D001551:Benz(a)Anthracenes / Q000378:metabolism*; D001711:Biotransformation; D004247:DNA / Q000378:metabolism*; D018736:DNA Adducts; D066298:In Vitro Techniques; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013237:Stereoisomerism
D001551:Benz(a)Anthracenes; D018736:DNA Adducts; C071159:dibenz(a,j)anthracene-DNA adduct; C079612:dibenz(a,h)anthracene-3,4-diol; D004247:DNA; C026486:1,2,5,6-dibenzanthracene