These are scientific publications for Targeted Metabolomics using an Agilent LC/MS system. Please note that the links below will take you to outside of Agilent’s website to PubMed.
1. Lithospermic acid B is more responsive to silver ion (Ag+) than rosmarinic acid in Salvia miltiorrhiza hairy root cultures.
Xiao Y, Gao S, Di P, Chen J, Chen W, Zhang L.
Biosci Rep. 2009 Feb 11. [Epub ahead of print]
Lithospermic acid B (LAB) is a dimer of rosmarinic acid (RA), and has been suggested to be derived from RA, but the detailed biosynthesis process has not yet been identified. The accumulation of RA has been intensively investigated in the plant species of Boraginaceae and Lamiaceae. Our study reported an abiotic elicitor, silver ion (Ag+, 15 microM) did not stimulate RA accumulation but dramatically enhanced LAB from approx. 5.4% to 18.8% of dry weight in Salvia miltiorrhiza hairy root cultures, and their content was found perfectly competitive at each time point after treatment. Meanwhile, profiling analysis of genes and metabolites (intermediates) involved in RA synthesis pathway was performed, the result indicated several gene transcripts and metabolite accumulations showed temporal changes in abundance consistent with LAB production. Thus, a potential (putative) biosynthetic route from RA to LAB was presumed, which was suggested to be fantastically activated by Ag+ in Salvia miltiorrhiza hairy root cultures. Further intermediates monitoring and compound feeding experiments were applied to rank the strength of this hypothesis. Our study, for the first time, provides the evidence for that RA is precursor for leading to LAB synthesis.
2. Liquid chromatography/triple quadrupole tandem mass spectrometry with multiple reaction monitoring for optimal selection of transitions to evaluate nutraceuticals from olive-tree materials.
Luján RJ, Capote FP, Marinas A, de Castro MD.
Rapid Commun Mass Spectrom. 2008;22(6):855-64.
Optimal transitions have been selected for the identification and quantitation of the most interesting hydrophilic biophenols in extracts from olive-tree materials, which are of interest because of their nutraceutical properties. The tested materials were extra virgin olive oil, waste from oil production (known as alperujo), and olive-tree materials such as leaves, small branches and fruit stones. The identification and determination steps of the target biophenols are based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) with a triple quadrupole (QQQ) mass detector. The interface between the chromatograph and the QQQ was an electrospray ionization source operated in the negative ion mode. Highly selective identification of the biophenols was confirmed by multiple reaction monitoring (MRM) using the most representative transitions from the precursor ion to the different product ions. Quantitative MS/MS analysis was carried out by optimization and selection of the most sensitive transition for each analyte, which resulted in estimated detection limits of 5.10 to 11.65 ng/mL for the extracts. The biophenols were extracted from the tested samples by different methods: liquid-liquid extraction for virgin olive oil, microwave-assisted leaching for olive leaves, branches and stones, and pressurized liquid leaching for alperujo. This study provides valuable information about the most suitable source for the isolation of each nutraceutical biophenol and enables us to obtain a complete profile of them in Olea Europaea.
3. Simultaneous Quantification of Metabolites Involved in Central Carbon and Energy Metabolism Using Reversed-Phase Liquid Chromatography-Mass Spectrometry and in Vitro (13) C Labeling.
Yang WC, Sedlak M, Regnier FE, Mosier N, Ho N, Adamec J.
Anal Chem. 2008 Nov 14. [Epub ahead of print]
Comprehensive analysis of intracellular metabolites is a critical component of elucidating cellular processes. Although the resolution and flexibility of reversed-phase liquid chromatography-mass spectrometry (RPLC-MS) makes it one of the most powerful analytical tools for metabolite analysis, the structural diversity of even the simplest metabolome provides a formidable analytical challenge. Here we describe a robust RPLC-MS method for identification and quantification of a diverse group of metabolites ranging from sugars, phosphosugars, and carboxylic acids to phosphocarboxylics acids, nucleotides, and coenzymes. This method is based on in vitro derivatization with a (13)C-labeled tag that allows internal standard based quantification and enables separation of structural isomer pairs like glucose 6-phosphate and fructose 6-phosphate in a single chromatographic run. Calibration curves for individual metabolites showed linearity ranging over more than 2 orders of magnitude with correlation coefficients of R (2) > 0.9975. The detection limits at a signal-to-noise ratio of 3 were below 1.0 muM (20 pmol) for most compounds. Thirty common metabolites involved in glycolysis, the pentose phosphate pathway, and tricarboxylic acid cycle were identified and quantified from yeast lysate with a relative standard deviation of less than 10%.
4. Soluble epoxide hydrolase is a susceptibility factor for heart failure in a rat model of human disease.
Monti J, Fischer J, Paskas S, Heinig M, Schulz H, Gösele C, Heuser A, Fischer R, Schmidt C, Schirdewan A, Gross V, Hummel O, Maatz H, Patone G, Saar K, Vingron M, Weldon SM, Lindpaintner K, Hammock BD, Rohde K, Dietz R, Cook SA, Schunck WH,
Luft FC, Hubner N.
Nat Genet. 2008 May; 40(5):529-37.
We aimed to identify genetic variants associated with heart failure by using a rat model of the human disease. We performed invasive cardiac hemodynamic measurements in F2 crosses between spontaneously hypertensive heart failure (SHHF) rats and reference strains. We combined linkage analyses with genome-wide expression profiling and identified Ephx2 as a heart failure susceptibility gene in SHHF rats. Specifically, we found that cis variation at Ephx2 segregated with heart failure and with increased transcript expression, protein expression and enzyme activity, leading to a more rapid hydrolysis of cardioprotective epoxyeicosatrienoic acids. To confirm our results, we tested the role of Ephx2 in heart failure using knockout mice. Ephx2 gene ablation protected from pressure overload-induced heart failure and cardiac arrhythmias. We further demonstrated differential regulation of EPHX2 in human heart failure, suggesting a cross-species role for Ephx2 in this complex disease.
5. Uterine vascular function in a transgenic preeclampsia rat model.
Verlohren S, Niehoff M, Hering L, Geusens N, Herse F, Tintu AN, Plagemann A, LeNoble F, Pijnenborg R, Muller DN, Luft FC, Dudenhausen JW, Gollasch M, Dechend R.
Hypertension. 2008 Feb;51(2):547-53. Epub 2008 Jan 14.
We investigated intrauterine growth restriction, endothelial function, and uterine artery blood flow characteristics in a transgenic preeclampsia rat model with an activated renin-angiotensin system. We compared preeclamptic Sprague-Dawley (SD-PE) rats with normal pregnant Sprague-Dawley and nonpregnant Sprague-Dawley rats. We used transabdominal ultrasound and found that SD-PE rat embryos developed intrauterine growth restriction. Isolated uterine arteries from SD-PE rats incubated with phenylephrine exhibited an increased contractile response, whereas a single high dose of acetylcholine resulted in an impaired vasorelaxation compared with controls. Incremental acetylcholine doses increased relaxation of SD-PE vessels at low acetylcholine doses but caused a paradoxical contraction at higher acetylcholine doses. Indomethacin and a thromboxane-receptor antagonist (SQ 29,548) blocked this effect, suggesting maternal prostanoid-dependent endothelial dysfunction. SD-PE rats had a decreased prostacyclin (6-keto-prostaglandin F1alpha):thromboxane ratio in the serum compared with normal pregnant Sprague-Dawley rats or nonpregnant Sprague-Dawley. Surprisingly, the Doppler resistance index decreased during pregnancy in SD-PE compared with normal pregnant Sprague-Dawley rats, suggesting unimpaired uteroplacental flow in the uterine artery. Umbilical flow was unchanged with absent end-diastolic flow in all of the groups. Renin-angiotensin system activation-induced preeclampsia is associated with altered placentation, modified resistance index, and endothelial dysfunction. A disturbed prostacyclin:thromboxane ratio could be an important mediator.
6. Identification and determination of fat-soluble vitamins and metabolites in human serum by liquid chromatography/triple quadrupole mass spectrometry with multiple reaction monitoring.
Priego Capote F, Jiménez JR, Granados JM, de Castro MD.
Rapid Commun Mass Spectrom. 2007; 21(11):1745-54.
A method for determination of fat-soluble vitamins K(1), K(3), A, D(2), D(3) and E (as alpha- and delta-tocopherol) and metabolites 25-hydroxyvitamin D(2) and D(3) and 1,25-dihydroxyvitamin D(3) in human serum by liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) in positive mode is proposed. Highly selective identification of the target compounds in serum was confirmed by the most representative transitions from precursor ion to product ion. Quantitative MS/MS analysis was carried out by multiple reaction monitoring optimizing the most sensitive transition for each analyte in order to achieve low detection limits (from 0.012 to 0.3 ng/mL estimated with serum). The analysis was performed with 1 mL of serum, which was subjected to protein precipitation, liquid-liquid extraction to an organic phase, evaporation to dryness and reconstitution with methanol. The precision of the overall method ranged from 3.17-6.76% as intra-day variability and from 5.07-11.53% as inter-day variability. The method, validated by the standard addition method, provides complete information on the fat-soluble vitamins profile, which is of interest in clinical and metabolomics studies.
7. Saturated very-long-chain fatty acids promote cotton fiber and Arabidopsis cell elongation by activating ethylene biosynthesis.
Qin YM, Hu CY, Pang Y, Kastaniotis AJ, Hiltunen JK, Zhu YX.
Plant Cell. 2007 Nov; 19(11):3692-704. Epub 2007 Nov 9.
Fatty acids are essential for membrane biosynthesis in all organisms and serve as signaling molecules in many animals. Here, we found that saturated very-long-chain fatty acids (VLCFAs; C20:0 to C30:0) exogenously applied in ovule culture medium significantly promoted cotton (Gossypium hirsutum) fiber cell elongation, whereas acetochlor (2-chloro-N-[ethoxymethyl]-N-[2-ethyl-6-methyl-phenyl]-acetamide; ACE), which inhibits VLCFA biosynthesis, abolished fiber growth. This inhibition was overcome by lignoceric acid (C24:0). Elongating fibers contained significantly higher amounts of VLCFAs than those of wild-type or fuzzless-lintless mutant ovules. Ethylene nullified inhibition by ACE, whereas C24:0 was inactive in the presence of the ethylene biosynthesis inhibitor (l-[2-aminoethoxyvinyl]-glycine), indicating that VLCFAs may act upstream of ethylene. C24:0 induced a rapid and significant increase in ACO (for 1-aminocyclopropane-1-carboxylic acid oxidase) transcript levels that resulted in substantial ethylene production. C24:0 also promoted Ser palmitoyltransferase expression at a later stage, resulting in increased sphingolipid biosynthesis. Application of C24:0 not only stimulated Arabidopsis thaliana root cell growth but also complemented the cut1 phenotype. Transgenic expression of Gh KCS13/CER6, encoding the cotton 3-ketoacyl-CoA synthase, in the cut1 background produced similar results. Promotion of Arabidopsis stem elongation was accompanied by increased ACO transcript levels. Thus, VLCFAs may be involved in maximizing the extensibility of cotton fibers and multiple Arabidopsis cell types, possibly by activating ethylene biosynthesis.
8. Determination of the ubiquinol-10 and ubiquinone-10 (coenzyme Q10) in human serum by liquid chromatography tandem mass spectrometry to evaluate the oxidative stress.
Ruiz-Jiménez J, Priego-Capote F, Mata-Granados JM, Quesada JM, Luque de Castro MD.
J Chromatogr A. 2007 Dec 21;1175(2):242-8. Epub 2007 Oct 25.
A method for the rapid and simultaneous determination of ubiquinone-10 (coenzyme Q10, CoQ(10)) and the reduced form ubiquinol-10 (CoQ(10)H(2)) in human serum by LC-MS-MS with electrospray ionization (ESI) in the positive mode is here proposed. High selective identification and sensitive quantitation of both analytes have been carried out by monitoring the transition from the corresponding precursor ion to the product ion. Prior to the chromatographic analysis, serum samples (100 microl) were subject to a conventional pre-treatment based on protein precipitation, liquid-liquid extraction, evaporation to dryness and reconstitution with 95:5 methanol/hexane (v/v). The overall method has enabled to achieve low detection limits--5.49 and 15.8 ng/ml for CoQ(10) and CoQ(10)H(2), respectively--which were estimated with serum. The accuracy and potential matrix effects have been studied with spiked serum resulting recoveries between 92.82 and 106.97%. The proposed method has been applied to serum samples from healthy middle-age women, in which the CoQ(10)H(2)/CoQ(10) ratio has been used as marker of oxidative stress.