Preparation, isolation, and characterization of dibenzo [a,l] pyrene diol epoxide-deoxyribonucleoside monophosphate adducts by HPLC and fluorescence line-narrowing spectroscopy

Dibenzo[a,l]pyrene (DB[a,l]P) is the most potent carcinogenic polycyclic ar omatic hydrocarbon that has been identified in the environment. Earlier stu dies in our laboratory indicated that more than 80% of the DB[a,l]P-DNA add ucts formed in vitro were depurinating adducts and that most of the stable adducts were formed from diol epoxide intermediates. To complete the profil e of both stable and depurinating adducts of DB[a,l]P, we have synthesized standard adducts by reacting 3'-dAMP or 3'-dGMP with either (+/-)-anti- or (+/-)-syn-dibenzo[a,l]pyrene 11,12-dihydrodiol 13,14-epoxide (DB[a,l]PDE). The adducts were separated by HPLC with an ion-pair column and were identif ied by fluorescence line-narrowing spectroscopy (FLNS), A total of six pair s of stereoisomers along with another stable DB[a,l]PDE-DNA adduct were suc cessfully isolated and identified. Pairs of (+/-)-trans and (+/-)-cis isome rs were expected to be formed from the reaction of anti-DB[a,l]PDE with eit her dAMP or dGMP. While we were able to identify two pairs of stereoisomeri c (+/-)-syn-DB[a,l]PDE-dAMP (cis and trans) and two pairs of stereoisomeric (+/-)-anti-DB [a,l]PDE-dAMP (cis and tl ans) adducts, identification of al l the stereoisomers of dGMP adducts proved to be impossible. A pair of (+/- )-syn-trans-DB[a,l]PDE-dGMP adducts, a pair of(+/-)-anti-cis-DB[a,l]PDE-dGM P adducts, and one syn-cis-DB[a,l]PDE-dGMP adduct were conclusively identif ied by FLNS. These standard adducts will be used to identify the stable DNA adducts formed by DB[a,l]P and DB[a,l]PDE in vitro and in vivo.