32P-Postlabelling/HPLC Analysis of DNA Adducts Formed from Chrysene and its Metabolites

Abstract

Abstract Direct reaction of the syn- and anti-isomers of 1,2-dihydroxy-3,4-oxy-1,2,3,4-tetrahydrochrysene and the anti-1,2,9-trihydroxy-3,4-oxy-1,2,3,4-tetrahydrochrysene with DNA resulted predominantly in covalent binding to deoxyguanosine as evidenced by 32P-postlabelling with ion-exchange TLC and reversed-phase HPLC. The major adduct formed by syn-1,2,9-trihydroxy-3,4-oxy-1,2,3,4-tetrahydrochrysene resulted from covalent binding to deoxyadenosine. Metabolic activation of chrysene and three metabolites by aroclor-induced rat-liver homo-genate in the presence of calf-thymus DNA or in vivo following topical application to mouse skin yielded similar adduct patterns upon 32P-postlabelling/TLC analysis. However, high resolution reversed-phase HPLC allowed identification of the major adduct formed by chrysene and the 1,2-dihydroxy-1,2-dihydrochrysene as being identical to the deoxyguanosine adduct formed by anti-1,2-dihydroxy-3,4-oxy-1,2,3,4-tetrahydrochrysene. Similarly, 3-hydroxychrysene and the 1,2,9-trihydroxy-1,2-dihydrochrysene gave a major adduct that cochro-matographed with a product obtained from direct reaction of anti-1,2,9-trihydroxy-3,4-oxy-1,2,3,4-tetrahydrochrysene. This more polar adduct was also formed as a minor adduct in the skin of mice treated with chrysene. These results confirm earlier studies showing that chrysene is metabolically activated to DNA binding species via a bay region diol-epoxide as well as via a phenolic triol-epoxide.