Interactions of S-(2-haloethyl)-mercapturic acid analogs with plasmid DNA

Vadi, Helena; Schasteen, Charles S.; Reed, Donald J.

doi:10.1016/0041-008x(85)90383-7

Cited by 26 publications

(7 citation statements)

References 24 publications

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“…1 mM S-(2-chloroethyl)cysteine, an established DNA strandbreaking agent(22). This result is in line with previous work by Vamvakas et al(1,23), who demonstrated DNA strand breaks in vitro and in vivo with chlorothioketene generated by β-lyase-catalyzed cleavage of S-1,2-(dichlorovinyl)-L-cysteine.…”

supporting

confidence: 90%

Reactivity of Haloketenes and Halothioketenes with Nucleobases: Reactions in Vitro with DNA

Müller

Birner

Sander

et al. 1998

Chem. Res. Toxicol.

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Ketenes are important and highly reactive intermediates. Thioketenes are formed by cysteine conjugate beta-lyase-dependent biotransformation of 1-halovinylcysteine S-conjugates which are metabolites of several halogenated olefins. Nucleic acid constituents react with haloketenes and halothioketenes in vitro. Thioketenes induce DNA strand breaks in incubations of 1,2-dichlorovinyl 2-nitrophenyl disulfide, a thioketene precursor, with pBr 322 plasmid DNA. After treatment of single-stranded or native calf thymus DNA with chlorothioketene generated by the hydrolysis of 1,2-dichlorovinyl 2-nitrophenyl disulfide, the formation of 3,N4-thioacetylcytosine could be demonstrated. N6-(Dichloroacetyl)adenine and N4-(dichloroacetyl)cytosine, however, adducts formed by dichloroketene in vitro, are labile to hydrolysis. Therefore, the binding of this compound to DNA constituents in intact DNA is difficult to demonstrate. Substitution of one chlorine atom by fluorine allowed us to use 19F NMR as a tool to demonstrate the formation of adducts by dihaloketenes in intact DNA. N6-(Chlorofluoroacetyl)adenine and N4-(chlorofluoroacetyl)cytosine were synthesized (yields 77%, 15%, respectively) as references and characterized by LC/MS, 1H, 13C, and 19F NMR, FT-IR, and elemental analysis. To demonstrate the ability of dihaloketenes to bind to DNA, poly-dA (1 mg) and calf thymus DNA (10 mg) were suspended in DMF and treated with different concentrations of chlorofluoroketene (50-200 micromol). Analysis of the polymeric DNA by 19F NMR showed one doublet at -137.2 ppm downfield from the reference (CFCl3). A doublet at -146.9 ppm, characteristic for chlorofluoroacetic acid, an expected product of DNA adduct hydrolysis, was not detected. These results demonstrate the formation of a stable adenine adduct by dihaloketenes in intact calf thymus DNA.

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supporting

confidence: 90%

Reactivity of Haloketenes and Halothioketenes with Nucleobases: Reactions in Vitro with DNA

Müller

Birner

Sander

et al. 1998

Chem. Res. Toxicol.

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“…Coinciding with this decrease was an increase in size of one of the previously minor peaks. This latter peak, which eluted near the void volume of the column, was assigned to HEG on the basis of the previously observed propensity of CEG to hydrolyze to HEG (21). This assignment was subsequently confirmed by observing that this peak cochromatographed with an authentic sample of HEG.…”

Section: Resultsmentioning

confidence: 59%

Identification of the reactive glutathione conjugate S-(2-chloroethyl)glutathione in the bile of 1-bromo-2-chloroethane-treated rats by high-pressure liquid chromatography and precolumn derivatization with o-phthalaldehyde

Marchand¹,

Reed²

1989

Chem. Res. Toxicol.

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The conjugation of glutathione with 1,2-dihaloethanes leads to the formation of S-(2-haloethyl)glutathione which, following intramolecular cyclization, produces an electrophilic thiiranium ion. The extent to which the formation of the thiiranium ion is responsible for the toxicity associated with 1,2-dihaloethanes has been difficult to determine because of the inherent instability of the compound under physiological conditions. The goal of this study was to attempt to identify a putative precursor of the thiiranium ion, S-(2-chloroethyl)glutathione (CEG), in the bile of rats treated with 1,2-dihaloethanes such as 1-bromo-2-chloroethane (BCE). In order to detect the presence of CEG, a precolumn procedure for derivatizing the amine of CEG with o-phthalaldehyde/2-mercaptoethanol (OPA/MCE) was developed. Studies with a model compound, S-ethylglutathione, indicated that the derivatization reaction between S-ethylglutathione and OPA/MCE proceeded rapidly and under mild conditions. The resulting fluorescent adduct of S-ethylglutathione was detected at low concentrations following separation by reverse-phase HPLC. Derivatization of CEG with OPA/MCE followed by preparative HPLC and mass spectral analysis revealed that the major fluorescent adduct in the reaction mixture was the expected 1-[(2-hydroxyethyl)thio]-2-substituted-isoindole derivative of CEG. Also present in the derivatization reaction mixture were small quantities of S-(2-hydroxyethyl)glutathione, the product of CEG hydrolysis, and a product involving the addition of MCE to CEG. Analysis of the bile samples obtained from bile-cannulated rats treated with BCE showed the presence of a peak corresponding to CEG. Over a 3-h interval, 2% of the BCE administered was excreted into the bile as CEG.

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“…These data support the theory that GSH conjugation is more important in DNA alkylation and mutagenesis than is the oxidative metabolic pathway (Guengerich et al, 1987;Ozawa and Guenferich, 1983; and references therein). The identification of this adduct also indicates that y-glutamyltransferase-catalyzed cleavage of glutamic acid to produce S-(2-chloroethyl)cysteine is not required for bioactivation in this instance, as had been suggested by other work (Vadi et al, 1985). The relevance of the guanyl N7 -adduct is not clear, particularly since this position is not in a base-pairing region and since N7 purine lesions are thought to be rarely associated with mutations.…”

Section: Gsh-dependent Metabolism Of Haloalkanesmentioning

confidence: 67%