FORMATION OF 1,N-6-ETHENOADENILLE AND 3,N-4-ETHENOCYTOSINE BY LIPID-PEROXIDATION PRODUCTS AND NUCLEIC-ACID BASES

Lipid peroxidation (LPO) products are known to interact with DNA, yiel ding several types of adduct with nucleobases. In this study, we demon strate the formation of two ethenobase adducts, 1,N-6-ethenoadenine an d 3,N-4-ethenocytosine, by reaction of LPO products with nucleic acid bases. Rat liver microsomes were incubated at 37 degrees C for 30 min in the presence of inducers of LPO [Fe(II) or cumene hydroperoxide] an d adenine or cytosine nucleotides or nucleosides, followed by further heating at 80 degrees C for 30 min to complete the reactions. The ethe no adducts detected after immunoaffinity chromatography were 1,N-6-eth eno-cAMP and 1,N-6-etheno-2'-deoxyadenosine (HPLC/fluorimetry), 3,N-4- etheno-2'-deoxycytidine (competitive radioimmunoassay), and 1,N-6-ethe no-2'-deoxyadenosine 3'-monophosphate and 3,N-4-etheno-2'-deoxycytidin e 3'-monophosphate (P-32-postlabeling). Incubation of arachidonic acid supplemented with Fe(II) also led to the formation of the 1,N-6-ethen o adduct from cAMP. LPO intermediates that may be involved are discuss ed. These data suggest that etheno adducts may be markers of DNA damag e associated with LPO.