Bis-butanediol-mercapturic acid (bis-BDMA) as a urinary biomarker of metabolic activation of butadiene to its ultimate carcinogenic species

Abstract

Human carcinogen 1,3-butadiene (BD) undergoes metabolic activation to 3,4-epoxy-1-butene (EB), hydroxymethylvinyl ketone (HMVK), 3,4-epoxy-1,2-butanediol (EBD) and 1,2,3,4-diepoxybutane (DEB). Among these, DEB is by far the most genotoxic metabolite and is considered the ultimate carcinogenic species of BD. We have shown previously that BD-exposed laboratory mice form 8- to 10-fold more DEB-DNA adducts than rats exposed at the same conditions, which may be responsible for the enhanced sensitivity of mice to BD-mediated cancer. In the present study, we have identified 1,4-bis-(N-acetyl-L-cystein-S-yl)butane-2,3-diol (bis-BDMA) as a novel DEB-specific urinary biomarker. Isotope dilution high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry was employed to quantify bis-BDMA and three other BD-mercapturic acids, 2-(N-acetyl-L-cystein-S-yl)-1-hydroxybut-3-ene/1-(N-acetyl-L-cystein-S-yl)-2-hydroxy-but-3-ene (MHBMA, from EB), 4-(N-acetyl-L-cystein-S-yl)-1,2-dihydroxybutane (DHBMA, from HMVK) and 4-(N-acetyl-L-cystein-S-yl)-1,2,3-trihydroxybutane (THBMA, from EBD), in urine of confirmed smokers, occupationally exposed workers and BD-exposed laboratory rats. Bis-BDMA was formed in a dose-dependent manner in urine of rats exposed to 0-200 p.p.m. BD by inhalation, although it was a minor metabolite (1%) as compared with DHBMA (47%) and THBMA (37%). In humans, DHBMA was the most abundant BD-mercapturic acid excreted (93%), followed by THBMA (5%) and MHBMA (2%), whereas no bis-BDMA was detected. These results reveal significant differences in metabolism of BD between rats and humans.

High throughput HPLC–ESI−-MS/MS methodology for mercapturic acid metabolites of 1,3-butadiene: Biomarkers of exposure and bioactivation

“…22 THBMA concentrations were also determined in the same urine samples using HPLC-ESI − -MS/MS methodology recently developed in our laboratory. 18;33 We found that MHBMA, DHBMA, THBMA, and the metabolic ratio MHBMA/(MHBMA+DHBMA+THBMA) were correlated with BD exposure concentrations. Furthermore, significant associations were also observed between BD urinary mercapturic acids and their corresponding hemoglobin adducts, N , N -(2,3-dihydroxy-1,4-butadiyl)-valine ( pyr -Val) and 2,3,4-trihydroxybutyl-valine (THB-Val).…”

“…Among the three BD-mercapturic acids, the order of urinary concentrations was DHBMA > THBMA > MHBMA, consistent with previous report in smokers. 38 Occupationally exposed workers were exposed to significantly higher concentrations of BD (0.55 ± 0.50 mg/m 3 ) than control workers (0.007 ± 0.005 mg/m 3 ) (Table 2) and hence the concentrations of all three urinary BD-mercapturic acids were increased in occupationally exposed workers as compared to controls (Table 2). …”

“…18;36 In brief, samples (10 µl) were injected onto a SIELC Primesep D column (2.1×100 mm, 5 µm particle size) connected to a guard column (Primesep D; 2.1×10 mm). The HPLC-MS/MS system consisted of an Agilent 1100 HPLC (Agilent Technologies, Santa Clara, CA) interfaced to a Thermo-Finnigan TSQ Quantum Discovery mass spectrometer (Thermo Scientific Corp., Waltham, MA).…”

“…18;24;25 bis -BDMA, a specific biomarker of DEB, is found in urine of BD-exposed laboratory rats and mice, but is not detectable in urine of smokers and workers occupationally exposed to BD, probably because of the inefficient formation of DEB in humans. 26 Several mass spectrometry-based methods have been developed for quantification of MHBMA and DHBMA in human urine. 20;23–25;27–32 However, many of these methods require a large sample volume (> 0.5 ml) and are not amenable to high throughput analysis (Table S-1).…”

Study of urinary 2-{[2-(acetylamino-2-carboxyethyl]sulfanyl}butanedioic acid, a mercapturic acid of rats treated with maleic acid

“…Although the metabolism of MA is not well understood, glutathione-S-transferase (GST) usually plays an important role in detoxification of industrial chemicals to form their corresponding glutathione conjugates, which are further metabolized to N-acetyl cysteine adducts, also named as mercapturic acids (Habig et al, 1974;Hecht et al, 2008). These mercapturic acids have been well studied to serve as biomarkers to assess current exposures for these chemicals in our living environments and/or at workplaces (Alary et al, 1995;Eckert et al, 2013;Huang et al, 2007;Kotapati et al, 2014;Kuiper et al, 2010;Maestri et al, 1997;Perbellini et al, 2002). If MA is also detoxified by GST, the resulting MA glutathione conjugates can be further metabolized to 2-{[2-(acetylamino)-2-carboxyethyl]sulfanyl}butanedioic acid, the mercapturic acid of MA (MAMA) excreted through urine.…”