Measurement of <i>S</i>‐methylcysteine and <i>S</i>‐methyl‐mercapturic acid in human urine by alkyl‐chloroformate extractive derivatization and isotope‐dilution gas chromatography–mass spectrometry

Rubino, Federico Maria; Pitton, Michael Bernhard; Fabio, Daniela Di; Meroni, Giuseppe; Santaniello, Enzo; Caneva, Enrico; Pappini, Marco; Colombi, A

doi:10.1002/bmc.1451

Cited by 10 publications

(6 citation statements)

References 39 publications

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“…The average (n = 9) urinary concentration of SMCSO was 38.03 ± 21.28 μM, and SMC was 2.73 ± 0.61 μM. SMC levels were comparable with previous published reports [34].…”

Section: Resultssupporting

confidence: 89%

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An LC-MS/MS Method to Measure S-Methyl-l-Cysteine and S-Methyl-l-Cysteine Sulfoxide in Human Specimens Using Isotope Labelled Internal Standards

et al. 2019

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This is the first report describing an analytical method for quantitative analysis of two naturally occurring sulphur compounds, S-methyl-l-cysteine (SMC) and S-methyl-l-cysteine sulfoxide (SMCSO), in human body fluids using isotope-labelled internal standards and liquid chromatography-mass spectrometry (LC-MS)/MS techniques. This method was validated according to the guideline of the Royal Society of Chemistry Analytical Methods Committee. It offers significant advantages including simple and fast preparation of human biological samples. The limits of detection of SMC were 0.08 µM for urine and 0.04 µM for plasma. The limits of detection of SMCSO were 0.03 µM for urine and 0.02 µM for plasma. The calibration curves of all matrices showed linearity with correlation coefficients r2 > 0.9987. The intra and inter day precisions in three levels of known concentrations were >10% and >20%, respectively. The quantification accuracy was 98.28 ± 5.66%. The proposed method would be beneficial for the rapid and accurate determination of the SMC and SMCSO in human plasma and urine samples using by isotope labelled internal standards.

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“…The average (n = 9) urinary concentration of SMCSO was 38.03 ± 21.28 μM, and SMC was 2.73 ± 0.61 μM. SMC levels were comparable with previous published reports [34].…”

Section: Resultssupporting

confidence: 89%

“…Furthermore, only a few studies have described the measurement of its reduced form ( S -methyl- l -cysteine, SMC). SMC analysis has been reported using LC-MS [32,33], GC-MC [34] and HPLC/ECD [23].…”

Section: Introductionmentioning

confidence: 99%

An LC-MS/MS Method to Measure S-Methyl-l-Cysteine and S-Methyl-l-Cysteine Sulfoxide in Human Specimens Using Isotope Labelled Internal Standards

et al. 2019

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“…Endogenous catabolism of SMC is extensive (88%) but relatively slow as 41% is excreted within 24 h as urine . Under rare circumstances, SMC‐containing proteins can be synthesized endogenously during xenobiotic metabolism . Taken together, these findings indicate that serum SMC is specific to dry bean intake.…”

Section: Discussionmentioning

confidence: 95%

Identification and monitoring of metabolite markers of dry bean consumption in parallel human and mouse studies

Perera

Young

Zhang

et al. 2015

Molecular Nutrition Food Res

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Scope Aim of the study was to identify and monitor metabolite markers of dry bean consumption in parallel human and mouse studies that each had shown chemopreventive effects of dry bean consumption on colorectal neoplasia risk. Methods and Results Using liquid chromatography/mass spectroscopy +/− electrospray ionization and gas chromatography/mass spectroscopy, serum metabolites of dry beans were measured in 46 men before and after a four-week dry bean-enriched diet (250 g/d) and 12 mice that received a standardized diet containing either 0 or 10% navy bean ethanol extract for 6 weeks; we also investigated fecal metabolites in the mice. The serum metabolites identified in these controlled feeding studies were then investigated in 212 polyp-free participants from the Polyp Prevention Trial who self-reported either increased (≥+31 g/d from baseline), high dry bean intake of ≥42 g/d in year 3 or low, unchanged dry bean consumption of <8 g/d; serum was analyzed from baseline and year 3. Serum pipecolic acid and S-methyl-cysteine were elevated after dry bean consumption in human and mouse studies and reflected dry bean consumption in the Polyp Prevention Trial. Conclusions Serum levels of pipecolic acid and S-methyl-cysteine are useful biomarkers of dry bean consumption.

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“…[1] I have been asked by some researchers, as the inventor of the chloroformate methodology [2,3], to comment on the "optimized protocol" as claimed in the abstract. The procedure, presented as a technique for "global metabolic profiling" is a lot else than that.…”

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confidence: 99%

Letter to the Editor regarding “GC–MS with ethyl chloroformate derivatization for comprehensive analysis of metabolites in serum and its application to human uremia”

Hušek

2012

Anal Bioanal Chem

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Dear Sir, In connection with the paper published by Tao et al.[1] I have been asked by some researchers, as the inventor of the chloroformate methodology [2,3], to comment on the "optimized protocol" as claimed in the abstract. The procedure, presented as a technique for "global metabolic profiling" is a lot else than that. It might work for the purpose to which it was applied, i.e. identification of the metabolites associated with human uremia, but it should not be pursued as a general tool "suitable for serum-based metabolic profiling studies" (Abstract). The method is substantially inferior in both ECF-mediated derivatization of amino acids, compared with the original detailed study [4], and the method used for serum sample workup, as described, e.g., in 1995 [5]. Let me briefly draw attention to the basic faults that reduce the effectiveness of the assay.First, replacing chloroform by hexane in the extraction step hampers transfer of polar products (serine, asparagine, glutamine) into the organic phase, and strongly reduces extraction of some others (glycine), as is apparent from the chromatographic record. The comment that "extraction efficiencies of chloroform and n-hexane are comparable" is thus completely incorrect, and to justify use of the latter by "facilitated removal of the hexane upper layer from the vial" is correct regarding sample handling but incorrect analytically.Second, the reason for the proposed two-step ECF derivatization, with intermediate basification of the aqueous layer, is declared as "exhibiting better derivatization efficiency and providing more useful information". In which way? The opposite seems to be true. One would expect at least augmented yields of the dibasic amino acids but lysine, ornithine, and histidine are absent from the record. Comparing the figure with the GC record of the original study [4] one can see this lapse, especially in yields of the later eluted analytes. The repeated treatment of the aqueous layer after the first extraction of the products did not result in any improvement, as already shown in 1997; the efficiency of extraction of the derivatized amino acids with chloroform was close to 100% [6].Third, treating serum with ethanol directly leads to disruption of lipoproteins, so massive amounts of neutral lipids, cholesterol esters, acylglycerols, and phospholipids are liberated and co-extracted with the derivatized amino acids. Their injection into the system leads to progressive poisoning of the inlet and the stationary phase, because the low-volatility species cannot be eluted from common stationary phases within the temperature range used. This phenomenon was, surprisingly, not discussed, although clear evidence of worsening GC-MS conditions was mentioned (p. 2887): "all of the samples from each batch were analyzed within 48 h, and maintenance of the equipment was carried out after every 48-h analysis", without giving the reason for this. Simple removal of the neutral lipids by hexane extraction, while retaining amino, fatty, and other carboxylic acids ...

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Measurement of S‐methylcysteine and S‐methyl‐mercapturic acid in human urine by alkyl‐chloroformate extractive derivatization and isotope‐dilution gas chromatography–mass spectrometry

Cited by 10 publications

References 39 publications

An LC-MS/MS Method to Measure S-Methyl-l-Cysteine and S-Methyl-l-Cysteine Sulfoxide in Human Specimens Using Isotope Labelled Internal Standards

An LC-MS/MS Method to Measure S-Methyl-l-Cysteine and S-Methyl-l-Cysteine Sulfoxide in Human Specimens Using Isotope Labelled Internal Standards

Identification and monitoring of metabolite markers of dry bean consumption in parallel human and mouse studies

Letter to the Editor regarding “GC–MS with ethyl chloroformate derivatization for comprehensive analysis of metabolites in serum and its application to human uremia”

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