Identification and quantitation of hepatic DNA adducts formed in B6C3F₁ mice from 1'-hydroxy-2', 3'-dehydroestragole: comparison of the adducts detected with the l'-³H-labelled carcinogen and by ³²P-postlabelling

Abstract

The identities and levels of DNA adducts formed in mouse liver after administration of the hepatocarcinogen [1'-3H]1'-hydroxy-2',3'-dehydroestragole obtained by analysis of the 3H-containing adducts were compared with those found by 32P-postlabelling analysis. As previously observed the two diastereomers of N2-(dehydroestragol-1'-yl)-deoxyguanosine were the only adducts detected by use of the tritiated carcinogen. Similarly, the unresolved diastereomers of N2-(dehydroestragol-1'-yl)-deoxyguanosine-3',5'-diphosphate were the only adducts detected by the postlabelling procedure. Analysis by 32P-postlabelling of defined mixtures of the normal deoxynucleoside-3'-phosphates and synthetic N2-(dehydroestragol-1'-yl)-deoxyguanosine-3'-phosphate showed that recovery of the labelled adduct was about 60% of that of the normal nucleotides. Likewise, the levels of the adduct in the hepatic DNA from mice treated with 1'-hydroxydehydroestragole, as determined by 32P-postlabelling, were generally 60-80% of those obtained by analysis for the tritiated adducts. Since 1'-oxodehydroestragole-deoxyadenosine adducts, the major products obtained on reaction of 1'-oxodehydroestragole with DNA in vitro, were not detected by 32P-postlabelling in the hepatic DNA from mice treated with 1'-hydroxydehydroestragole, these data provide further evidence that the covalent binding of 1'-hydroxydehydroestragole to liver DNA in vivo does not involve the 1'-oxo derivative.