³²P-postlabelling/HPLC analysis of various styrene-induced DNA adducts in mice

Abstract

Styrene oxide (SO), a reactive metabolite of styrene, modifies DNA at several nucleophilic sites. In the present work we have determined the SO–DNA adducts in vitro and in vivo by two different versions of ³²P-postlabelling/HPLC assays. When anionexchange cartridges were used for adduct enrichment the β-isomer of 7-substituted guanines was detected in in vitro SO-treated DNA as well as in mice lungs exposed to styrene at 750 and 1500 mg m⁻³ for 21 days (6 h day⁻¹, 7 days week⁻¹). In the lungs, the adduct levels were 6.5 and 23 per 10⁸ nucleotides for the two doses, respectively. When the nuclease P1 resistant adducts were studied by the ³²P-postlabelling/HPLC assay involving nuclease P1/prostatic acid phosphatase hydrolysis, the main adducts in in vitro-treated DNA were the α-isomer of N²-substituted guanine, β-isomers of 1-substituted adenine and 3-substituted uracil. β1-SO–adenine adduct was detected in the mice lung tissues after conversion of the 1-substituted adduct to the βN⁶-SO–adenine adduct by the Dimroth rearrangement. The 1-adenine adduct levels for the two doses were found to be 0.17 and 0.51 per 10⁸ nucleotides. The current results show the potential of using the 7-guanine and 1-adenine adducts as biomarkers in biomonitoring of styrene exposure.

Keywords::

• DNA adducts ³²P-postlabelling Styrene Styrene 7,8-OXIDE