Comparison of the solid-matrix luminescence properties of benzo(a)pyrene-DNA adducts on alpha-cyclodextrin/NaCl and trehalose/NaCl matrices

The characterization of (±)-anti-benzo[a]pyrene diolepoxide–DNA adducts and (±)-anti-dibenzo[a,l]pyrene diolepoxide–DNA adducts in the same DNA sample using solid-matrix phosphorescence

Solid-matrix phosphorescence (SMP) spectra and lifetimes were used to characterize the (+/-)-anti-benzo[a]pyrene diolepoxide [(+/-)-anti-B[a]PDE] and (+/-)-anti-dibenzo[a,l]pyrene diolepoxide [(+/-)-anti-DB[a,l]PDE] bonded to the same sample of DNA. SMP spectra and lifetimes were also acquired for two samples of DNA that had only (+/-)-anti-B[a]PDE or (+/-)-anti-DB[a,l]PDE bonded to the individual samples of DNA. A detailed comparison of the SMP properties was made among the three samples of DNA. The SMP excitation spectra for the (+/-)-anti-B[a]PDE-DNA and the (+/-)-anti-DB[a,l]PDE-DNA adducts were very similar. However, the SMP emission spectra of the two DNA adduct systems were very dissimilar with a major emission band for the (+/-)-anti-B[a]PDE-DNA adducts appearing at 613 nm and for the (+/-)-anti-DB[a,l]PDE-DNA adducts a major band was at 558 nm. It was possible to selectively use SMP emission wavelengths and obtain a SMP excitation of spectrum of the (+/-)-anti-DB[a,l]PDE-DNA adducts in the dual adducted DNA sample without the (+/-)-anti-B[a]PDE-DNA adducts emitting SMP. In addition, it was shown that the SMP emission spectrum of the dual adducted DNA sample could be used to detect both adduct systems in the modified DNA sample. It was demonstrated that the SMP lifetimes could be effectively employed to characterize the dual adducted DNA sample. For example, the SMP decay curve for the (+/-)-anti-DB[a,l]PDE-DNA adducts could be acquired without any SMP emission from the (+/-)-anti-B[a]PDE-DNA adducts. Also, ln(SMP intensity) versus time plots were very useful in characterizing the dual adducted DNA sample.

Solid-matrix fluorescence quenching of benzo[e]pyrene and (+/-)-anti-dibenzo[a, l]pyrene diolepoxide-DNA adducts

The solid-matrix fluorescence (SMF) quenching of benzo[e]pyrene and (+/-)-anti-dibenzo[a, l]pyrene-11,12-diol-13,14-epoxide ((+/-)-antiDB[a, l]PDE)-DNA adducts with thallium nitrate (TlNO(3)) and sodium iodide (NaI) was examined and several SMF quenching models were developed. The SMF quenching data for B[e]P with either TlNO(3) or NaI fit a two-independent-binding-site model. However, the SMF quenching of (+/-)-anti-DB[a, l]PDE-DNA adducts with TlNO(3) fits a sphere of action model, but quenching with NaI was modeled with the two-independent-binding-site model. The data were compared with earlier SMF quenching data for 7,8,9,10-tetrahydroxytetrahydro-benzo[a]pyrene (tetrol I-1) and (+/-)-anti-benzo[a]pyrene-trans-7,8-dihydrodiol-9,10-epoxide ((+/-)-anti-BPDE)DNA adducts. The interpretation of the SMF quenching data for the (+/-)-anti-DB[a, l]PDE-DNA adducts was distinctively different than the interpretation of the SMF quenching data for the (+/-)-antiBPDE-DNA adducts. This initial study shows that SMF quenching has the potential to characterize polycyclic aromatic hydrocarbonDNA adducts with different numbers of aromatic rings. In addition, the data indicated that external and intercalated DNA adducts interacted with heavy-atom salts in dissimilar fashions. The new SMF methodology developed is useful for the characterization of both polycyclic aromatic hydrocarbon-DNA adducts and metabolites from polycyclic aromatic hydrocarbons.