Conditions for sample preparation and quantitative HPLC/MS-MS analysis of bulky adducts to serum albumin with diolepoxides of polycyclic aromatic hydrocarbons as models.

Stable adducts to serum albumin (SA) from electrophilic and genotoxic compounds/metabolites can be used as biomarkers for quantification of the corresponding in vivo dose. In the present study, conditions for specific analysis of stable adducts to SA formed from carcinogenic polycyclic aromatic hydrocarbons (PAH) were evaluated in order to achieve a sensitive and reproducible quantitative method. Bulky adducts from diolepoxides (DE) of PAH, primarily DE of benzo[a]pyrene (BPDE) and also DE of dibenzo[a,l]pyrene (DBPDE) and dibenzo[a,h]anthracene (DBADE), were used as model compounds.

Cob(I)alamin for trapping butadiene epoxides in metabolism with rat S9 and for determining associated kinetic parameters.

The reduced state of vitamin B(12), cob(I)alamin, acts as a supernucleophile that reacts ca. 10(5) times faster than standard nucleophiles, for example, thiols. Methods have been developed for trapping electrophilically reactive compounds by exploiting this property of cob(I)alamin.

Enantioselective formation of methyl sulfone metabolites of 2,2',3,3',4,6'-hexachlorobiphenyl in rat.

Several nonsymmetric polychlorinated biphenyl (PCB) congeners form atropisomers due to steric hindrance of free rotation around the phenyl-phenyl bond. It is evident from the literature that both chiral PCB congeners and their atropisomeric methylsulfonyl-PCB metabolites, formed in higher animals and in humans, are present in biota as nonracemic mixtures. Chiral methylsulfonyl-PCBs are strongly dominated by one of the atropisomers in mammalian tissues.

Characterization of alkyl-cobalamins formed on trapping of epoxide metabolites of 1,3-butadiene.

Analytical methods facilitating studies of electrophilically reactive and genotoxic compounds in vitro and in vivo are needed. The strong nucleophile, cob(I)alamin, formed by reduction of Vitamin B12 [cob(III)alamin], may be used for trapping and analysis of 1,2-epoxides and other electrophiles. In the present study, cob(I)alamin is evaluated as an analytical tool for 1,2-epoxide metabolites (oxiranes) of 1,3-butadiene.

Analysis of DNA-phosphate adducts in vitro using miniaturized LC-ESI-MS/MS and column switching: phosphotriesters and alkyl cobalamins.

DNA-phosphate adducts are known to be formed by a variety of alkylating agents. Due to little or no repair of DNA-phosphate adducts, these adducts may offer increased possibilities of both identifying and quantifying DNA adducts. The formation of DNA-phosphate adducts leads to a complete esterification of the phosphate group giving rise to a phosphotriester configuration.

Evidence for phosphate adducts in DNA from mice treated with 4-(N-Methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK).

The weakly alkylating capacity of phosphotriesters (PTE) has been used for the determination of adducts to phosphate groups in DNA by specific transfer to the strongly nucleophilic compound cob(I)alamin [Cbl(I)]. When enzymatically degraded liver DNA from mice treated with 1-(N-methyl-N-nitrosamino)-4-(3-[3H]pyridyl)-4-oxobutane ([3H]NNK) was added to Cbl(I), a 4-(3-[3H]pyridyl)-4-hydroxy-1-butyl-cobalamin ([3H]PHB-Cbl) complex was formed and determined by HPLC and liquid scintillation counting. The PHB-Cbl formed was compared with a synthetic standard verified by LC/MS and 1H NMR and corresponds to phosphate adducts formed from the pyridyloxobutylating species from NNK and from the pyridylhydroxybutylating species from NNAL, NNK being to a large extent converted to NNAL in vivo.