32P-Postlabelling of DNA adducts formed by allyl glycidyl ether in vitro and in vivo

32P-Postlabelling analysis of allyl glycidyl ether-treated DNA after adductenrichment on anion-exchange cartridges revealed two major and one minorDNA adducts. The major adducts were shown to originate from alkylation atN-7-guanine and N-1-adenine, respectively, while the minor adduct was atN-3-cytosine. In addition, rearrangement products of the 1-adenine and3-cytosine adducts to N6-adenine and 3-uracil were indicated. The relativeamounts of adenine, cytosine and uracil products appeared to be dependentupon conditions (in particular pH) during sample processing and analysis.When nuclease P1 was used for adduct enrichment the adenine, cytosine anduracil adducts, but not the 7-guanine adduct, were detected. The labellingefficiency of the 7- guanine adduct standard was 40-45%. Total recovery ofthis adduct from allyl glycidyl ether-modified DNA was 9-12%. The labellingefficiency of the 1-adenine adduct standard was 78-82%. Total recovery ofthis adduct from DNA was approximately 20% when using anion-exchangechromatography for adduct enrichment and 30-34% when using nuclease P1.Preliminary analysis of DNA from mice treated with allyl glycidyl etherindicated 57 times higher level of the 7-guanine adduct, per unit dose, inskin DNA (120 per 10(8) normal nucleotides) after topical application whencompared to liver DNA after i.p. administration. The 1- adenine adductcould not be quantified in liver DNA (due to an interfering backgroundproduct present in untreated animals) and the level of the 3-cytosineadduct was below the detection limit of the method. After topicalapplication the level of the 1 adenine adduct in skin DNA was approximately30 per 10(8), using either column or nuclease P1 enrichment. The 3-cytosineadduct was detected in skin, but was not quantified.