Preparation of electrophoric derivatives on N7-(2-hydroxyethyl)guanine, an ethylene oxide DNA adduct

Allam, Kariman; Saha, Manasi; Giese, Roger W.

doi:10.1016/s0021-9673(00)97001-8

Cited by 20 publications

(21 citation statements)

References 18 publications

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“…N7-(Hydroxyethyl)xanthine was benzylated at the N-1 and N-3 positions of xanthine during the first derivatization (26). The third PFBBr attacked the hydroxyl group of N7-HEG during the second derivatization (26). When the HRMS system was tuned to a resolving power of 1000, the EC/NCI-MS spectra exhibited no molecular ions, with the most abundant fragment ion being (M -181) -at m/z 555, due to the cleavage of one pentafluorobenzyl (PFB) group from the N-1 or N-3 position of xanthine (16).…”

Section: Resultsmentioning

confidence: 99%

A Gas Chromatography/Electron Capture/Negative Chemical Ionization High-Resolution Mass Spectrometry Method for Analysis of Endogenous and Exogenous N7-(2-Hydroxyethyl)guanine in Rodents and Its Potential for Human Biological Monitoring

Scheller

Ranasinghe

et al. 1999

Chem. Res. Toxicol.

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A gas chromatography/electron capture/negative chemical ionization high-resolution mass spectrometry (GC/EC/NCI-HRMS) method was developed for quantitating N7-(2-hydroxyethyl)guanine (N7-HEG) with excellent sensitivity and specificity. [4,5,6,8-(13)C(4)]-N7-HEG was synthesized, characterized, and quantitated using HPLC/electrospray ionization mass spectrometry (HPLC/ESI-MS) so it could serve as an internal standard. After being converted to its corresponding xanthine and derivatized with pentafluorobenzyl (PFB) bromide twice, the PFB derivative of N7-HEG was characterized using GC/EC/NCI-HRMS carried out at full scan mode. The most abundant fragment was at m/z 555, with a molecular formula of C(21)H(9)N(4)O(3)F(10), resulting from the loss of one PFB group. By monitoring m/z 555.0515 (analyte) and m/z 559.0649 (internal standard), this assay demonstrated a linear relationship over a range of 1 fmol to 1 pmol of N7-HEG versus 20 fmol of [(13)C(4)]-N7-HEG on column. The limit of detection (LOD) for the complete assay was 600 amol (S/N = 5) injected on column. The variation of this assay was within 15% from 1 to 20 fmol of N7-HEG versus 2 fmol of [(13)C(4)]-N7-HEG with four replications for each calibration standard. Two hundred to three hundred micrograms of spleen DNA of control rats and mice and 100 microg of spleen DNA of rats and mice exposed to 3000 ppm ethylene for 6 h/day for 5 days were analyzed using GC/EC/NCI-HRMS. The amounts of N7-HEG varied from 0.2 to 0.3 pmol/micromol of guanine in tissues of control rats. Ethylene-exposed animals had 5-15-fold higher N7-HEG levels than controls. This assay was able to quantitate N7-HEG in 25-30 microg of DNA from human lymphocytes with excellent specificity. This was due in part to human tissues having 10-15-fold higher amounts of endogenous N7-HEG than rodents. These results show that this GC/EC/NCI-HRMS method is highly sensitive and specific and can be used in biological monitoring and molecular dosimetry and molecular epidemiology studies.

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Section: Resultsmentioning

confidence: 99%

A Gas Chromatography/Electron Capture/Negative Chemical Ionization High-Resolution Mass Spectrometry Method for Analysis of Endogenous and Exogenous N7-(2-Hydroxyethyl)guanine in Rodents and Its Potential for Human Biological Monitoring

Scheller

Ranasinghe

et al. 1999

Chem. Res. Toxicol.

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“…Derivatization of alkylated DNA adducts with electrophores such as PFBBr, and analysis of the derivatives using electron-capture mass spectrometry (EC-MS), has been proved to be highly sensitive and specific. 16,21 The sensitivity of this method was attributed to the fact that the PFB derivatives are strong electrophores and are able to capture thermal or near-thermal electrons to form dominant anion products with approximately 100% efficiency. 18,20 Results from the present study are consistent with the observation that analysis of PFB-derivatized 7-MG using EC-MS operated under SIM mode is extremely sensitive, and has a detection limit in the 20 amol range at signal-to-noise (S/N) ratio !10; however, the limit of quantitation was estimated to be in the 100 amol range in tissue samples (data not shown) at S/N ratio greater than 10.…”

Section: Discussionmentioning

confidence: 99%

“…The procedures have been described previously. 16 Briefly, N7-methylguanine (2 mg) was converted into N7-methylxanthine using degassed 6 M HCl solution (200 mL) and tert-butyl nitrite (50 mL) at 48C for 4 h. N7-Methylxanthine was extracted from the product mixture using HPLC water (200 mL) and ethyl acetate (600 mL). The aqueous phase was dried in vacuo and derivatized with PFBBr in acetonitrile in the presence of K 2 CO 3 (dehydrated at 608C for at least 1 h) at room temperature.…”

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confidence: 99%

“…16 This method was adopted to analyze 7-hydroxyethylguanine using gas chromatography coupled with high-resolution mass spectrometry (GC/HRMS), with excellent sensitivity and specificity. 9 In the present work the earlier method 16 was adopted to analyze 7-MG in DNA samples extracted from livers of mice treated with dacarbazine, a chemotherapeutic drug. 13 C 4 -Labeled 7-MG was synthesized to serve as an internal standard to improve the quantitation of 7-MG.…”

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confidence: 99%

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Analysis of 7‐methylguanine using isotope dilution and gas chromatography/electron‐capture negative chemical ionization mass spectrometry

Chiang

Huang

Uang

et al. 2005

Rapid Comm Mass Spectrometry

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This paper presents results obtained for in vivo endogenous and exogenous 7-methylguanine (7-MG) analyzed using a method incorporating gas chromatography with electron-capture negative chemical ionization mass spectrometry and isotope dilution (GC/EC-ID-MS). 13C4-Labeled 7-MG was synthesized to serve as an internal standard to improve accuracy of quantitation, and was used to analyze 7-MG in livers of control mice and dacarbazine-treated mice. The results confirm that 7-MG in tissue DNA can be measured using this GC/EC-ID-MS method with excellent sensitivity and specificity. Administration of 0, 30, and 60 mg/kg dacarbazine to mice led to dose-dependent increases in the formation of 7-MG. The results indicate that this method could be applied to the analysis of endogenous and exogenous 7-MG in human tissues for future molecular epidemiology studies on potential health effects caused by methylating agents.

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“…Analysis of the PFB-derivative with electron-capture negative chemicalionization mass spectrometry (ECNCI-MS) in full-scan mode yields the most-abundant anion [M À 181] À ions at m/z ¼ 555 for N7-HEG and m/z ¼ 559 for the d 4 -labeled N7-HEG by the loss of one PFBBr group (Saha, Abushamaa, & Giese, 1995). By monitoring the most-abundant fragment ion, GC/ECNCI-MS SIM analysis of this derivative demonstrated excellent sensitivity and specificity for quantification of N7-HEG (Saha et al, 1989;Allam, Saha, & Giese, 1990). An on-column detection limit of 1.3 amol (1 Â 10 À18 mol) was reported at a signal-to-noise ratio of 13 (Abdel-Baky & Giese, 1991).…”

Section: B Gc/ms Analysis Of Eo-induced Dna Adductsmentioning

confidence: 99%

The application of mass spectrometry in molecular dosimetry: Ethylene oxide as an example

Chiang

Shih

et al. 2011

Mass Spectrometry Reviews

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Mass spectrometry plays an increasingly important role in the search for and quantification of novel chemically specific biomarkers. The revolutionary advances in mass spectrometry instrumentation and technology empower scientists to specifically analyze DNA and protein adducts, considered as molecular dosimeters, derived from reactions of a carcinogen or its active metabolites with DNA or protein. Analysis of the adducted DNA bases and proteins can elucidate the chemically reactive species of carcinogens in humans and can serve as risk-associated biomarkers for early prediction of cancer risk. In this article, we review and compare the specificity, sensitivity, resolution, and ease-of-use of mass spectrometry methods developed to analyze ethylene oxide (EO)-induced DNA and protein adducts, particularly N7-(2-hydroxyethyl)guanine (N7-HEG) and N-(2-hydroxyethyl)valine (HEV), in human samples and in animal tissues. GC/ECNCI-MS analysis after HPLC cleanup is the most sensitive method for quantification of N7-HEG, but limited by the tedious sample preparation procedures. Excellent sensitivity and specificity in analysis of N7-HEG can be achieved by LC/MS/MS analysis if the mobile phase, the inlet (split or splitless), and the collision energy are properly optimized. GC/ECNCI-HRMS and GC/ECNCI-MS/MS analysis of HEV achieves the best performance as compared with GC/ECNCI-MS and GC/EI-MS. In conclusion, future improvements in high-throughput capabilities, detection sensitivity, and resolution of mass spectrometry will attract more scientists to identify and/or quantify novel molecular dosimeters or profiles of these biomarkers in toxicological and/or epidemiological studies.

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Preparation of electrophoric derivatives on N7-(2-hydroxyethyl)guanine, an ethylene oxide DNA adduct

Cited by 20 publications

References 18 publications

A Gas Chromatography/Electron Capture/Negative Chemical Ionization High-Resolution Mass Spectrometry Method for Analysis of Endogenous and Exogenous N7-(2-Hydroxyethyl)guanine in Rodents and Its Potential for Human Biological Monitoring

A Gas Chromatography/Electron Capture/Negative Chemical Ionization High-Resolution Mass Spectrometry Method for Analysis of Endogenous and Exogenous N7-(2-Hydroxyethyl)guanine in Rodents and Its Potential for Human Biological Monitoring

Analysis of 7‐methylguanine using isotope dilution and gas chromatography/electron‐capture negative chemical ionization mass spectrometry

The application of mass spectrometry in molecular dosimetry: Ethylene oxide as an example

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