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 [l'-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 dia-stereomers of N²-(dehydroestragol-l'-yl)-deoxyguanosine were the only adducts detected by use of the tritiated carcinogen. Similarly, the unresolved diastereomers of N²-(de-hydroestragol-l'-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-(dehydro-estragol'-l-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 l'-hydroxydehydroestra-gole, as determined by ³²P-postlabelling, were generally 60 – 80% of those obtained by analysis for the tritiated adducts. Since l'-oxodehydroestragole-deoxyadenosine adducts, the major products obtained on reaction of l'-oxodehydro-estragole with DNA in vitro, were not detected by ³²P-post-labelling in the hepatic DNA from mice treated with 1'-hydroxydehydroestragole, these data provide further evidence that the covalent binding of l'-hydroxydehydroestragole to liver DNA in vivo does not involve thel'-oxo derivative.