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

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