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Chen J, Qin Y, Zhang M. [Determination of anabolic steroid hormones in animal muscle tissues by gas chromatography/mass spectrometry]. Se Pu 2006; 24:19-22. [PMID: 16827303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023] Open
Abstract
A gas chromatography/mass spectrometry (GC/MS) method was developed for the determination of multi-residues of steroid anabolic hormones epitestosterone (ETS), testosterone 17-propionate (PTS), nandrolone (17beta-NT), 17alpha-methyltestosterone (MTS), 17beta-estradiol (17beta-ES), estriol ( EST), 17alpha-ethinylestradiol (EES), estrone (ESN) and 17beta-estradiol 3-benzoate (BES) in the muscle tissues of various animal species. Homogenized tissue samples were enzymatically digested in acetate buffer (pH 5.0). Consequently, methanol was added and the mixtures were extracted under ultrasonication incubation. Clean-up was carried out for at least two times with methyl tert-butyl ether (MTBE) liquid-liquid partitioning followed by a reversed-phase solid phase extraction (SPE) cartridge purification. The eluate with methanol was evaporated to dryness by N2 at 40 degrees C and derivatization was achieved with N-methyl-N-( trimethylsilyl) trifluoroacetamide/iodotrimethylsilane/dithioerythritol (MSTFA-TMIS-DTE) at 60 degrees C for 45 min. The reaction mixture was injected into a gas chromatograph with a DB-1 capillary column coupled with a mass spectrometer. The samples were tested by different selected ion monitoring modes with electron impact (EI) source for the androgens and estrogens. The limits of quantitation (LOQ) for the above 9 hormones were in the range of 1.0 - 2.0 microg/kg. At the 2.0 microg/kg LOQ spiked level, the mean recoveries were within 62.5% - 80.5%, and the relative standard deviations were within 12.5% - 26.8%. The real sample tests showed this method can be used for the sensitive and accurate determination of multi-steroid anabolic hormones residues in biological muscle samples.
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Affiliation(s)
- Jie Chen
- Food Inspection Center, Guangzhou Entry and Exit Inspection and Quarantine Bureau, Guangzhou 510623, China.
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Friestad GK, Korapala CS, Ding H. Dual Activation in Asymmetric Allylsilane Addition to Chiral N-Acylhydrazones: Method Development, Mechanistic Studies, and Elaboration of Homoallylic Amine Adducts. J Org Chem 2005; 71:281-9. [PMID: 16388647 DOI: 10.1021/jo052037d] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] Chiral N-acylhydrazones derived from commercially available 4-benzyl-2-oxazolidinone provide a rigid, conformationally restricted template to impart facial selectivity in additions to C=N bonds. In the presence of indium(III) trifluoromethanesulfonate [In(OTf)3], N-acylhydrazones undergo highly diastereoselective fluoride-initiated additions of allylsilanes (aza-Sakurai reaction). Mechanistic studies including control experiments and comparisons with allyltributylstannane, allylmagnesium bromide, and allylindium species implicate a dual activation mechanism involving addition of an allylfluorosilicate species to a chelate formed from In(OTf)3 and the chiral N-acylhydrazone. The N-N bonds of the adducts are readily cleaved in a two-step protocol to provide synthetically useful homoallylic N-trifluoroacetamides. Further elaboration of the latter compounds through Wacker oxidation and olefin metathesis provides diversely functionalized building blocks and expands the potential applications of this C-C bond construction approach to asymmetric amine synthesis.
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Affiliation(s)
- Gregory K Friestad
- Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA.
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53
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Abstract
Nanoscaled TiO2 powders with narrow size dispersion were prepared in supercritical carbon dioxide via non-hydrolytic acylation/deacylation of titanium alkoxide precursors with or without tris-fluorination. The microstructures of these powders were characterized by spectroscopic (FTIR, TGA, and XRD), microscopic (SEM or TEM), and surface area (BET) measurements. Photocatalytic oxidation of 1-octanol on these calcined TiO2 powders and on commercial T805 TiO2 suspended in aerated supercritical carbon dioxide revealed relative reactivity controlled by the powder microstructures. Calcined TiO2 prepared from titanium(IV) isopropoxide and trifluoroacetic anhydride was effectively dispersed in aerated supercritical carbon dioxide under stirring and exhibited high photocatalytic oxidation activity.
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Affiliation(s)
- Guangqing Guo
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27606, USA
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54
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B'Hymer C, Butler MA, Cheever KL. Comparison and evaluation of analysis procedures for the quantification of (2-methoxyethoxy)acetic acid in urine. Anal Bioanal Chem 2005; 383:201-9. [PMID: 16158298 DOI: 10.1007/s00216-005-0048-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Revised: 06/24/2005] [Accepted: 06/29/2005] [Indexed: 11/29/2022]
Abstract
Several extraction and derivatization procedures were evaluated for the quantification of (2-methoxyethoxy)acetic acid (MEAA) in urine. MEAA is a metabolite and a biomarker for exposure to 2-(2-methoxyethoxy)ethanol, a glycol ether with widespread use in various industrial applications and the specific use as an anti-icing additive in the military jet fuel formulation JP-8. Quantification of glycol ether biomarkers is an active area of analytical research. Various sample preparation procedures were evaluated: liquid-liquid extraction (LLE) using ethyl acetate yielded the highest recovery, and solid-phase extraction (SPE) gave low recovery of MEAA. Two derivatization procedures were thoroughly investigated and validated, namely, silylation of MEAA with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA), and esterification of MEAA using ethanol. Quantification was performed by gas chromatography (GC) with a mass spectrometer as detector and using a polydimethylsiloxane (HP-1) capillary column. Deuterated 2-butoxyacetic acid (d-BAA) was used as an internal standard. Recovery studies of spiked human urine demonstrated the accuracy and precision of both procedures. The limit of detection (LOD) and other figures of merit for both derivatization procedures will be discussed in detail. Applications of these analysis procedures are also discussed.
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Affiliation(s)
- Clayton B'Hymer
- US Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Division of Applied Research and Technology, Cincinnati, OH, 45226, USA.
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55
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Paik MJ, Lee HJ, Kim KR. Simultaneous retention index analysis of urinary amino acids and carboxylic acids for graphic recognition of abnormal state. J Chromatogr B Analyt Technol Biomed Life Sci 2005; 821:94-104. [PMID: 15894518 DOI: 10.1016/j.jchromb.2005.04.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Revised: 04/11/2005] [Accepted: 04/18/2005] [Indexed: 11/18/2022]
Abstract
Simultaneous profiling analysis of urinary amino acids (AAs) and carboxylic acids (CAs) was combined with retention index (I) analysis for graphic recognition of abnormal metabolic state. The temperature-programmed I values of the AA and CA standards measured as ethoxycarbonyl (EOC)/methoxime (MO)/tert-butyldimethylsilyl (TBDMS) derivatives were used as the reference I values. Urine samples were subjected to the sequential EOC, MO and TBDMS reactions for the analysis by gas chromatography (GC) and GC-mass spectrometry. The complex GC profiles were then transformed into their respective I patterns in bar graphic forms by plotting the normalized peak area ratios (%) of the identified AAs and CAs against their reference I values as the identification numbers. When the present method was applied to infant urine specimens from normal controls and patients with inherited metabolic diseases such as phenylketonuria, maple syrup urine disease, methylmalonic aciduria or isovaleric aciduria, each I pattern of bar graph more distinctly displayed quantitative abundances of urinary AAs and CAs in qualitative I scale, thus allowing graphic discrimination between normal and abnormal states.
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Affiliation(s)
- Man-Jeong Paik
- Biometabolite Analysis Laboratory, College of Pharmacy, Sungkyunkwan University, 300 Chunchun-dong, Suwon, Kyunggi-do 440-746, South Korea
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56
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Canosa P, Rodriguez I, Rubí E, Cela R. Optimization of solid-phase microextraction conditions for the determination of triclosan and possible related compounds in water samples. J Chromatogr A 2005; 1072:107-15. [PMID: 15881465 DOI: 10.1016/j.chroma.2004.11.032] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A solid-phase microextraction (SPME) method for the determination of triclosan, methyl triclosan, 2,4-dichlorophenol and 2,3,4-trichlorophenol (considered as possible triclosan metabolites) in water samples was optimised. Analytes were first concentrated on a SPME fibre, directly exposed to the sample, and then triclosan and the two chlorinated phenols on-fibre silylated using N-methyl-N-(tert.-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA). Methyl triclosan remained unaffected during the derivatization step. Compounds were determined using gas chromatography in combination with mass spectrometry (GC-MS). Influence of different factors on the efficiency of extraction and derivatization steps was systematically investigated. Using a polyacrylate (PA) fibre quantification limits below 10 ng/l, and acceptable relative standard deviations, were obtained for all compounds after an extraction time of 30 min. On-fibre silylation was carried out in only 10 min. Moreover, the efficiency of the procedure was scarcely affected by the type of water sample. The method was applied to several samples of treated and raw wastewater, triclosan was found in all samples, at concentrations from 120 to 14,000 ng/l, and 2,4-dichlorophenol in most of them, at levels up to 2222 ng/l.
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Affiliation(s)
- P Canosa
- Departamento de Química Analítica, Nutrición y Bromatología, Instituto de Investigación y Análisis Alimentario, Universidad de Santiago de Compostela, Santiago de Compostela 15782, Spain
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57
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Zhang L, Liu Y, Xie MX, Qiu YM. Simultaneous determination of thyreostatic residues in animal tissues by matrix solid-phase dispersion and gas chromatography–mass spectrometry. J Chromatogr A 2005; 1074:1-7. [PMID: 15941032 DOI: 10.1016/j.chroma.2005.03.086] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
A method for determination of thyreostatic residues in animal tissues by matrix solid-phase dispersion (MSPD) and gas chromatography-mass spectrometry in selected ion detection mode was developed. Thyreostatic compounds in different matrices were extracted and purified by combination of MSPD and subsequent solid-phase extraction. Silica gel was selected as the solid support of both procedures and the conditions of the procedures were optimized. Thyreostats were derivatized with pentafluorobenzylbromide (PFBBr) in strong basic medium and then with N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA), which can improve the yields of derivatization for thyreostats, the repeatability, and therefore the limits of detection (LOD) of thyreostats. The limits of detection reached 10 microg/kg (2-thiouracil, 6-methyl-2-thiouracil and 6-propyl-2-thiouracil), 20 microg/kg (6-phenyl-2-thiouracil) and 50 microg/kg (tapazole) with high recoveries (more than 70% for most of thyreostats) and relative standard deviations between 4.5% and 8.7%.
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Affiliation(s)
- Lei Zhang
- Analytical & Testing Center of Beijing Normal University, Xinjiekowaidajie 19, Beijing 100875, China
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58
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Abstract
Metabolism of benzene is fairly complex yielding several reactive metabolites that could form adducts with macromolecules such as DNA and proteins. Systemic availability of these reactive species can be estimated by measuring the corresponding adducts of these species with serum albumin or hemoglobin. We have shown previously that serum albumin adducts of benzene oxide and 1,4-benzoquinone increased in a dose-dependent manner in rodents and humans exposed to benzene. However, formation of macromolecular adducts of other reactive metabolites, such as benzene diolepoxide and E,E-muconaldehyde, has not received much attention despite the demonstrated mutagenicity and/or carcinogenicity of these metabolites. We studied the reaction of isomers of benzene diolepoxide, namely syn-((+/-)BDE1) and anti-BDE ((+/-)BDE2), with sulfhydryl groups in vitro. The half-life of BDE2 in 0.1 M ammonium acetate buffer (pH 7.6) was (5.46 h) longer that that in serum albumin in the same buffer (3.83 h) indicating the reaction of BDE with nucleophilic sites on albumin. Reaction products between these and L-cysteine, and GSH were identified and characterized by mass spectrometry in an attempt to develop an assay to quantify these adducts in serum albumin.
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Affiliation(s)
- Suramya Waidyanatha
- Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7400, USA. suramya.unc.edu
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Gunnar T, Ariniemi K, Lillsunde P. Determination of 14 benzodiazepines and hydroxy metabolites, zaleplon and zolpidem as tert-butyldimethylsilyl derivatives compared with other common silylating reagents in whole blood by gas chromatography–mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2005; 818:175-89. [PMID: 15734157 DOI: 10.1016/j.jchromb.2004.12.032] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Accepted: 12/22/2004] [Indexed: 11/30/2022]
Abstract
The most common commercially available silylating reagents, N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA), N,O-bis-(trimethylsilyl)trifluoroacetamide+1% trimethylchlorosilane (BSTFA+1% TMCS) and N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) were evaluated to achieve optimal derivatization conditions for analyzing various benzodiazepines based on gas chromatography-electron impact ionization-mass spectrometry (GC-EI-MS). Sensitivity, repeatability, retention times and stability of the derivatives, as well as specificity of mass fragmentation, were studied in detail. Also other parameters affecting the derivatization chemistry of benzodiazepines are discussed. tert-Butyldimethylsilyl (TBDMS) derivatives proved to be more stable, reproducible and sensitive than corresponding trimethylsilyl (TMS) derivatives for the GC-EI-MS analysis of benzodiazepines. Based on the TBDMS derivatives, a rapid, reliable, sensitive and quantitative GC-MS method was developed for the determination of 14 benzodiazepines and two hydroxy metabolites, as well as two non-benzodiazepine hypnotic agents, zolpidem and zaleplon, using 50 microl of whole blood. The method was completely validated in terms of accuracy, intra- and interday precision, limit of detection (LOD), limit of quantitation (LOQ), linearity, selectivity and extraction efficiency; these were all within the required limits, except for the accuracy of nitrazepam at a medium concentration level.
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Affiliation(s)
- Teemu Gunnar
- National Public Health Institute, Drug Research Unit, Mannerheimintie 166, 00300 Helsinki, Finland.
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60
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Pulici M, Quartieri F, Felder ER. Trifluoroacetic Anhydride-Mediated Solid-Phase Version of the Robinson−Gabriel Synthesis of Oxazoles. ACTA ACUST UNITED AC 2005; 7:463-73. [PMID: 15877475 DOI: 10.1021/cc049831h] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A traceless solid-phase synthesis of oxazoles 4 via Robinson-Gabriel reaction of solid-supported alpha-acylamino ketones 2 has been achieved. The reaction requires that the cyclization precursor be linked to a benzhydrylic-type linker (compounds 2) and that trifluoroacetic anhydride be used as the cyclodehydrating agent. The solvent has a dramatic effect on the latter reaction, which goes to completion and follows a cyclative-type mechanism only when an ethereal solvent is used. Different synthetic routes have been investigated toward assembling compounds 2. The most straightforward one, which we have validated more extensively, comprises the reaction of Merrifield alpha-methoxyphenyl (MAMP) resin with an alpha-amino ketone to form compounds 1, which are, in turn, acylated. Other methodologies and strategies allowing for the synthesis of compounds 1 that have been investigated include direct alkylation of Rink amide resin; reductive amination of the latter with alpha-keto aldehydes; reaction of MAMP resin with alpha-amino alcohols, followed by oxidation; and protection of Rink amide resin with either 2,4-dinitrosulfonyl or allyl group, followed by alkylation and removal of protecting group. In addition, we disclose a novel variant of the Ugi four-component reaction that allows for the preparation of compounds 2 in a single synthetic step.
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Affiliation(s)
- Maurizio Pulici
- Department of Chemistry, Nerviano Medical Sciences, Viale Pasteur 10, 20014 Nerviano (MI), Italy.
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61
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Rodenko B, Koch M, van der Burg AM, Wanner MJ, Koomen GJ. The Mechanism of Selective Purine C-Nitration Revealed: NMR Studies Demonstrate Formation and Radical Rearrangement of an N7-Nitramine Intermediate. J Am Chem Soc 2005; 127:5957-63. [PMID: 15839695 DOI: 10.1021/ja042590x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Modified purine derivatives are of great importance in biomedical sciences, and substitution reactions on the purine skeleton are intensively studied. In our laboratory, an efficient and selective purine C2-nitration reaction was developed using a mixture of tetrabutylammonium nitrate and trifluoroacetic anhydride. The resulting 2-nitro moiety appeared to be a versatile handle to introduce a variety of pharmacophores onto the purine skeleton. Since the mechanism of this selective purine C2-nitration reaction has remained unclear, we now present an extensive NMR study leading to its elucidation, using N9-Boc-protected 6-chloropurine as a model compound. Direct electrophilic aromatic nitration of the highly electron-deficient C2 position was excluded, and we demonstrate that this reaction occurs in a three-step process. Electrophilic attack by trifluoroacetyl nitrate on the purine N7 position results in a nitrammonium species that is trapped by a trifluoroacetate anion furnishing N7-nitramine intermediate 11. This intermediate was characterized at -50 degrees C by (1)H, (13)C, (15)N, and (19)F NMR. At T > -40 degrees C, the N7-nitramine intermediate undergoes a nitramine rearrangement, which generates a C2-nitro species that immediately eliminates TFA to give 2-nitro-6-chloro-9-Boc purine 10. The involvement of radicals during the nitramine rearrangement was unequivocally established by (15)N-CIDNP. Moreover, the emission signal observed for the rearranged product, 2-nitropurine 10, showed that it is primarily formed in an intermolecular process. A quantitative radical trapping experiment finally disclosed that 65-70% of the nitramine rearrangement takes place intermolecularly.
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Affiliation(s)
- Boris Rodenko
- Van't Hoff Institute for Molecular Sciences, Universiteit van Amsterdam, Nieuwe Achtergracht 129, NL-1018 WS Amsterdam, The Netherlands
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62
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Han E, Yang W, Lee J, Park Y, Kim E, Lim M, Chung H. Correlation of methamphetamine results and concentrations between head, axillary, and pubic hair. Forensic Sci Int 2005; 147:21-4. [PMID: 15541587 DOI: 10.1016/j.forsciint.2004.03.035] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2003] [Accepted: 03/09/2004] [Indexed: 11/16/2022]
Abstract
This study was designed to compare the qualitative results and concentrations of methamphetamine (MA) and its metabolite amphetamine (AP) in head hair and hair collected from different parts of the body (axillae and pubis). Hair from subjects (N = 14) suspected MA users was simultaneously collected. Hair preparation involved washing step, fine cutting, overnight extraction, derivatization by the trifluoroacetic anhydride, and gas chromatography/mass spectrometry (GC/MS) using selective ion monitoring. In this study, we found a good correlation of the qualitative results for MA between head hair and hair on other parts of the body, but there were some differences in concentrations of MA and AP. Namely, the concentrations of MA and AP were higher in axillary and pubic hair than in head hair.
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Affiliation(s)
- Eunyoung Han
- Department of Narcotics Analysis, National Institute of Scientific Investigation, 331-1 Shinwol 7-Dong, Yang-Chun Gu, Seoul, South Korea.
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Wanner MJ, Rodenko B, Koch M, Koomen GJ. New (1-deaza)purine derivatives via efficient C-2 nitration of the (1-deaza)purine ring. Nucleosides Nucleotides Nucleic Acids 2005; 23:1313-20. [PMID: 15571251 DOI: 10.1081/ncn-200027566] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Nitration of substituted (1-deaza)purines using a mixture of tetrabutylammonium nitrate (TBAN) and trifluoracetic acid anhydride (TFAA) was applied to prepare nitrosubstituted (1-deaza)purines at low temperature. The nitro group influences the system twofold: 1) it activates other substituents towards nucleophilic aromatic substitution and 2) it can be substituted itself leading to a variety of di-substituted (1-deaza)purines, also via solid phase syntheses. Several of the molecules obtained were studied for their antiprotozoal activity and for interactions with the different human adenosine receptors.
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Affiliation(s)
- M J Wanner
- Bioorganic Chemistry, Institute of Molecular Chemistry, University of Amsterdam, Amsterdam, The Netherlands
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64
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Abstract
The low penetration depth and high sputter rates obtained using polyatomic primary ions have facilitated their use for the molecular depth profiling of some spin-cast polymer films by secondary ion mass spectrometry (SIMS). In this study, dual-beam time-of-flight (TOF) SIMS (sputter ion, 5 keV SF(5)(+); analysis ion, 10 keV Ar(+)) was used to depth profile spin-cast multilayers of poly(methyl methacrylate) (PMMA), poly(2-hydroxyethyl methacrylate) (PHEMA), and trifluoroacetic anhydride-derivatized poly(2-hydroxyethyl methacrylate) (TFAA-PHEMA) on silicon substrates. Characteristic positive and negative secondary ions were monitored as a function of depth using SF(5)(+) primary ion doses necessary to sputter through the polymer layer and uncover the silicon substrate (>5 x10(14) ions/cm(2)). The sputter rates of the polymers in the multilayers were typically less than for corresponding single-layer films, and the order of the polymers in the multilayer affected the sputter rates of the polymers. Multilayer samples with PHEMA as the outermost layer resulted in lowered sputter rates for the underlying polymer layer due to increased ion-induced damage accumulation rates in PHEMA. Additionally, the presence of a PMMA or PHEMA overlayer significantly decreased the sputter rate of TFAA-PHEMA underlayers due to ion-induced damage accumulation in the overlayer. Typical interface widths between adjacent polymer layers were 10-15 nm for bilayer films and increased with depth to approximately 35 nm for the trilayer films. The increase in interface width and observations using optical microscopy showed the formation of sputter-induced surface roughness during the depth profiles of the trilayer polymer films. This study shows that polyatomic primary ions can be used for the molecular depth profiling of some multilayer polymer films and presents new opportunities for the analysis of thin organic films using TOF-SIMS.
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Affiliation(s)
- M S Wagner
- Surface and Microanalysis Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20889-8371, USA.
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Di Gioia ML, Leggio A, Le Pera A, Liguori A, Napoli A, Perri F, Siciliano C. Determination by gas chromatography/mass spectrometry of p-phenylenediamine in hair dyes after conversion to an imine derivative. J Chromatogr A 2005; 1066:143-8. [PMID: 15794565 DOI: 10.1016/j.chroma.2005.01.039] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this paper we describe an analytical method for the determination of p-phenylenediamine (PPDA) in hair dyes. In the adopted methodology the analyte is transformed into the corresponding imine derivative by treatment with benzaldehyde, and then analyzed by gas chromatography (GC) combined to mass spectrometry (MS), operating in SIM conditions. The direct and simultaneous chemical derivatization of the two amino functions of the analyte with benzaldehyde enhances the instrumental responses enabling the use of a sensitive and accurate method. Concentrations of PPDA in a set of commercial hair coloring creams are determined making use of N-benzylidene-4-methylbenzene-amine as a very stable internal standard which is easily prepared by condensation of 4-methylbenzene-amine with benzaldehyde. The regression calibration curves for PPDA in hair dyes are linear within 0.1 +/- 25 mg/ml with 0.99 as a typical correlation coefficient.
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Affiliation(s)
- Maria Luisa Di Gioia
- Dipartimento di Scienze Farmnnaceutiche, Università degli Studi della Calabria, Via P Bucci, Cubo 15/C, 1-87036 Arcavacata di Rende (CS), Italy
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66
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Njoku DB, Talor MV, Fairweather D, Frisancho-Kiss S, Odumade OA, Rose NR. A novel model of drug hapten-induced hepatitis with increased mast cells in the BALB/c mouse. Exp Mol Pathol 2005; 78:87-100. [PMID: 15713433 DOI: 10.1016/j.yexmp.2004.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Accepted: 10/14/2004] [Indexed: 01/13/2023]
Abstract
Clinical evidence suggests that idiosyncratic hepatitis following administration of halogenated volatile anesthetics is mediated by autoimmune responses. No murine model to study mechanisms of anesthetic-induced or any other form of drug-induced idiosyncratic hepatitis exists. Anesthetics are believed to trigger hepatitis by covalently linking a trifluoroacetyl (TFA) chloride hapten to hepatic proteins, forming haptenated self-proteins. To test this hypothesis, we developed a hapten-induced model of hepatitis by immunization with syngeneic S100 liver proteins covalently coupled to TFA (TFA-S100). We found that TFA-S100 induced hepatitis was more severe than disease induced by S100 plus adjuvants or by the adjuvant alone and was characterized by neutrophil, mast cell, and eosinophil infiltration. TFA-specific IgG1 antibodies directly correlated with hepatitis, whereas S100 autoantibodies did not. TNF-alpha, IL-1beta, and IL-6 released from splenocytes collected 2 weeks after TFA-S100 inoculation were increased resembling the elevated serum cytokines reported in patients with autoimmune hepatitis (AIH). Three weeks after inoculation, the peak of hepatitis, we noted decreased numbers of Kupffer cells and lower levels of IL-6 and IL-10 in the liver, cytokines produced by Kupffer cells. This is the first report, to our knowledge, of a hapten-induced model of hepatitis with immune and autoimmune features.
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Affiliation(s)
- Dolores B Njoku
- Department of Anesthesiology and Critical Care Medicine, The Johns Hopkins Medical Institutions, Blalock 906A, 600 North Wolfe Street, Baltimore, MD 21287, USA.
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Hata K, Hamamoto H, Shiozaki Y, Kita Y. A new synthesis of dienone lactones using a combination of hypervalent iodine(iii) reagent and heteropoly acid. Chem Commun (Camb) 2005:2465-7. [PMID: 15886772 DOI: 10.1039/b501792k] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The oxidation of non-phenolic alkanoic acid derivatives to oxygen heterocycles was investigated; a new oxidative route to dienone lactones has been developed using a combination of hypervalent iodine(III) reagent, phenyliodine(III) bis(trifluoroacetate)(PIFA), and heteropoly acid (HPA).
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Affiliation(s)
- Kayoko Hata
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6, Yamada-oka, Suita, Osaka 565-0871, Japan
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68
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Forsdahl G, Gmeiner G. Investigation of the silylation of ephedrines using N-methyl-N-trimethylsilyl-trifluoroacetamide. J Chromatogr B Analyt Technol Biomed Life Sci 2004; 811:201-8. [PMID: 15522721 DOI: 10.1016/j.jchromb.2004.09.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Accepted: 09/01/2004] [Indexed: 05/01/2023]
Abstract
This paper describes a gas chromatography (GC)--mass spectrometry (MS) method for the simultaneous quantification of ephedrine, pseudoephedrine, cathine, norephedrine and methylephedrine in urine. The sample preparation step includes solid phase extraction and derivatisation with N-methyl-N-trimethylsilyl-trifluoroacetamide (MSTFA). An evaluation of various silylation conditions compatible with screening methods in doping control analysis is presented. The method was found to be well suited for quantification of ephedrines in doping control.
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Affiliation(s)
- Guro Forsdahl
- Doping Control Laboratory, Chemical Analysis, ARC Seibersdorf Research GmbH, 2444 Seibersdorf, Austria
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69
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Klausmeyer P, Chmurny GN, McCloud TG, Tucker KD, Shoemaker RH. A novel antimicrobial indolizinium alkaloid from Aniba panurensis. J Nat Prod 2004; 67:1732-1735. [PMID: 15497951 DOI: 10.1021/np040114e] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Activity-guided fractionation of an Aniba panurensis organic solvent extract has led to the isolation of the novel alkaloid 6,8-didec-(1Z)-enyl-5,7-dimethyl-2,3-dihydro-1H-indolizinium, as the trifluoroacetic acid salt (1). Its structure was determined by NMR and mass spectrometry. Bioassays performed in vitro demonstrated toxicity of compound 1 to a drug-resistant strain of Candida albicans.
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Affiliation(s)
- Paul Klausmeyer
- Natural Products Support Group, Laboratory of Proteomics and Analytical Technologies, SAIC-Frederick, Inc, National Cancer Institute-Frederick, Maryland 21702-1201, USA
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70
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71
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VON BRAND T, JOHNSON TOBIE E, MEHLMAN B. The influence of some sulfhydryl inhibitors and of fluoroacetate on the oxygen consumption of some Trypanosomes. ACTA ACUST UNITED AC 2004; 35:273-300. [PMID: 15428514 DOI: 10.1002/jcp.1030350207] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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72
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73
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Kobayashi J, Nakamura M, Mori Y, Yamashita Y, Kobayashi S. Catalytic Enantio- and Diastereoselective Aldol Reactions of Glycine-Derived Silicon Enolate with Aldehydes: An Efficient Approach to the Asymmetric Synthesis of anti-β-Hydroxy-α-Amino Acid Derivatives. J Am Chem Soc 2004; 126:9192-3. [PMID: 15281803 DOI: 10.1021/ja047597t] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have developed an efficient method for the asymmetric synthesis of anti-beta-hydroxy-alpha-amino acid derivatives based on highly enantio- and diastereoselective aldol reactions of the silicon enolate derived from N-trifluoroacetylglycinate with aldehydes using a chiral zirconium catalyst. The resulting N-trifluoroacetyl group is easily cleaved under either acidic or basic conditions and can be used directly as a protecting group for further transformations.
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Affiliation(s)
- Jun Kobayashi
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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74
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Sabucedo AJ, Furton KG. Extractionless GC/MS analysis of γ-hydroxybutyrate and γ-butyrolactone with trifluoroacetic anhydride and heptafluoro-1-butanol from aqueous samples. J Sep Sci 2004; 27:703-9. [PMID: 15387466 DOI: 10.1002/jssc.200401718] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
gamma-Hydroxybutyrate (GHB) is a DEA Schedule I drug of abuse commonly spiked into beverages to incapacitate victims of sexual assault. GHB is a challenging drug for analysis by GC/MS because of its small size, charged nature, low volatility, and intramolecular esterification leading to gamma-butyrolactone (GBL). In this work an extractionless technique has been developed that allows for the use of an aqueous sample for direct derivatization. The technique uses a solution of trifluoroacetic anhydride (TFAA) and 2,2,3,3,4,4,4-heptafluoro-1-butanol (HFB) to derivatize the active hydrogens of GHB. The conversion of GBL into GHB can be forced under alkaline conditions by diluting the sample in 10 mM borate buffer, pH 12. GBL found in beverages intended for human consumption is treated as a Schedule I control substance analogue. Spikes of the two compounds into several beverage matrices gave quantitative recovery of GHB by GC/MS. The derivatization produces higher molecular mass products whose fragmentation pattern provides multiple peaks for confirmation and quantification. The concentration of GBL can also be indirectly determined by the method developed. Therefore, this extractionless technique is rapid, sensitive, and selective for the confirmation of the presence of GHB and GBL in commercial beverages.
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Affiliation(s)
- Alberto J Sabucedo
- Florida International University, University Park, Department of Chemistry and Biochemistry, Advanced Mass Spectrometry Facility, Miami, Florida 33199, USA.
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75
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Matthies A, Ezziddin S, Ulrich EM, Palmedo H, Biersack HJ, Bender H, Guhlke S. Imaging of prostate cancer metastases with 18F-fluoroacetate using PET/CT. Eur J Nucl Med Mol Imaging 2004; 31:797. [PMID: 14985862 DOI: 10.1007/s00259-003-1437-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Alexander Matthies
- Department of Nuclear Medicine, University Hospital Bonn, Sigmund-Freud-Strasse 25, 53105 Bonn, Germany.
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76
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Lee CY, Lin CF, Lee JL, Chiu CC, Lu WD, Wu MJ. Synthesis of Carbazoles via an Intramolecular Cyclization of 2-(6-Substituted 3(Z)-hexen-1,5-diynyl)anilines and Their Related Molecules. J Org Chem 2004; 69:2106-10. [PMID: 15058959 DOI: 10.1021/jo0303158] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Various 2-(6-substituted 3(Z)-hexen-1,5-diynyl)anilines 1a-g were treated with potassium tert-butoxide or potassium 3-ethylpentanoxide in NMP at 60 degrees C for 2 h to give the corresponding 5-substituted carbazoles 2a-g in 36-65% yields together with indoles 9a-g in 21-40% yields, respectively. Exposing the trifluoroacetamide analogues 10h-k under the same reaction conditions gave the carbazoles 2b-e in 37-57% yields and indoles 9b-e in 15-27% yields. Subsequent cyclizations of acetamide analogues 10a-g gave carbazoles 2a-g in 53-86% yields.
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Affiliation(s)
- Chia-Ying Lee
- Faculty of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung, Taiwan
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77
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LOTSPEICH WD, PETERS RA, WILSON TH. The inhibition of aconitase by 'Inhibitor fractions' isolated from tissues poisoned with fluoroacetate. Biochem J 2004; 51:20-5. [PMID: 14944527 PMCID: PMC1197782 DOI: 10.1042/bj0510020] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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78
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BUFFA P, PETERS RA, WAKELIN RW. Biochemistry of fluoroacetate poisoning; isolation of an active tricarboxylic acid fraction from poisoned kidney homogenates. Biochem J 2004; 48:467-77. [PMID: 14838868 PMCID: PMC1275352 DOI: 10.1042/bj0480467] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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79
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80
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ACKERMANN WW. The relation of the Krebs cycle to viral synthesis. II. The effect of sodium fluoroacetate on the propagation of influenza virus in mice. ACTA ACUST UNITED AC 2004; 93:635-42. [PMID: 14832407 PMCID: PMC2136068 DOI: 10.1084/jem.93.6.635] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A further study has been made of the relationship of reactions of the Krebs cycle to the propagation of influenza virus. By the administration of sublethal doses of sodium fluoroacetate which were found to increase the concentration of citrate in the mouse lung, it was possible to demonstrate a blocking of the citric acid cycle in that organ. Further, the intraperitoneal administration of these concentrations of fluoroacetate was found to inhibit markedly the propagation of influenza, Type A, virus in the lungs of mice. The inhibition was observed when the fluoroacetate was administered 15 minutes, 6 hours, or 12 hours after the mice were inoculated with virus. This effect was also demonstrable when the concentration of the viral inoculum was varied over a range of virus titers from 103.5 to 106.5. Sodium fluoroacetate was found to have no effect in vitro on the infectivity or hemagglutinating property of the virus. The significance of these findings with regard to chemotherapy and to the mechanism of viral synthesis is described.
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81
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Shareef A, Parnis CJ, Angove MJ, Wells JD, Johnson BB. Suitability of N,O-bis(trimethylsilyl)trifluoroacetamide and N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide as derivatization reagents for the determination of the estrogens estrone and 17α-ethinylestradiol by gas chromatography–mass spectrometry. J Chromatogr A 2004; 1026:295-300. [PMID: 14763757 DOI: 10.1016/j.chroma.2003.10.110] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
This paper describes apreviously unreported problem with the use of N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) and N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA) to derivatise the natural hormone estrone (E1) and the synthetic estrogen 17alpha-ethinylestradiol (EE2). The resulting trimethylsilyl (TMS) and t-butyldimethylsilyl (TBS) derivatives of EE2 were partially converted to their respective El derivatives. Therefore, these reagents may not be suitable for simultaneous determination of estrogens in environmental samples, which raises questions about the reliability of results from some earlier studies.
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Affiliation(s)
- Ali Shareef
- Colloid and Environmental Chemistry Laboratory, La Trobe University, PO Box 199, Bendigo, Vic. 3552, Australia.
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82
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Stehmann A, Schröder HF. Derivatisation of 4-nonylphenol and bisphenol A with halogenated anhydrides. Water Sci Technol 2004; 50:115-118. [PMID: 15497837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The aim of this work is to synthesize and characterise the halogenated derivatives of the endocrine disrupting compounds (EDCs) 4-nonylphenol (4-NP) and bisphenol A (BPA). Characterisation was performed after gas chromatographic (GC) separation on-line coupled to mass spectrometric (MS) detector and a Fourier Transform Infrared (FTIR) spectroscopic detector. Further structure elucidation was done applying Nuclear Magnetic Resonance spectroscopy (NMR). Two different approaches for the preparation of derivatives were evaluated. At first trifluoroacetyl derivatives were synthesized by the reaction of trifluoroacetic acid (TFA) anhydride and the EDCs in acetonitrile at a temperature of 50 degrees C for 30 minutes. In a second step the 4-NP was derivatised using trichloroacetic acid anhydride and triethylamine in diethyl ether at 20 degrees C for 30 minutes. After synthesis the halogenated NP and BPA derivatives were characterised applying GC/MS, GC/FTIR and NMR. Three indices for a successful derivatisation were observed: El-GC/MS proved a complete derivatisation presenting a characteristic fragmentation pattern for each derivative. The IR spectra obtained by GC/FTIR after derivatisation and separation confirmed the loss of the phenolic O-H stretching vibration at 3,600 cm(-1) while typical absorptions for halogenated compounds now were observed. The NMR-spectra contained the predicted resonance signals.
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Affiliation(s)
- A Stehmann
- Institut fuer Siedlungswasserwirtschaft, Aachen University, Templergraben 55, D-52056 Aachen, Germany.
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83
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Abstract
A method using GC-MS and derivatization with N-(t-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA) was developed for the analysis of 20 phenolic compounds in atmospheric samples (gas and particles). Air sampling was carried out using a Hi-Vol sampler with glass fibre filter and XAD-2 resin at a flow rate of 60 m(3) h(-1). The particle and gas phases were collected separately over a period of 4 h. Samples were Soxhlet extracted, evaporated to dryness under nitrogen and refilled with acetonitrile. 100 microl of these extracts were derivatized with 100 microl of MTBSTFA at 80 degrees C for 1 h under strong stirring. Phenolic compounds were injected into a GC-MS in splitless mode and quantified as their TBDMS derivatives in the SIM mode. Mass spectral analysis of the derivatives of the 20 compounds studied indicates that the spectra are highly specific showing an ion at [M - 57]+ which is useful for structure confirmation or analysis at low levels using selected ion monitoring. Quantification limits varied between 5 microg l(-1) and 10 microg l(-1) which correspond to 20 pg m(-3) and 40 pg m(-3) for 250 m(3) of air sampled. This method was successfully applied to atmospheric samples.
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Affiliation(s)
- Stephane Morville
- Centre de Geochimie de la Surface, UMR 7517 CNRS, Universite Louis Pasteur, Laboratoire de Physico-Chimie de l'Atmosphere, 1 rue Blessig, F-67084 Strasbourg Cedex, France
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84
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Thevis M, Opfermann G, Schänzer W. N-methyl-N-trimethylsilyltrifluoroacetamide-promoted synthesis and mass spectrometric characterization of deuterated ephedrines. Eur J Mass Spectrom (Chichester) 2004; 10:673-681. [PMID: 15531801 DOI: 10.1255/ejms.669] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Synthesis and mass spectrometric characterization of drugs or metabolites labeled by stable isotopes has been of great interest in fields of clinical, forensic and doping control analysis. Deuterated ephedrine and p-hydroxypseudoephedrine were prepared from corresponding amines by a novel procedure utilizing N- methyl-N-trimethylsilyltrifluoroacetamide and deuterated iodomethane. The mechanism of methylation was studied by mass spectrometry using phenylethylamine as a model compound, and a rearrangement based on an intermediate six-membered ring structure with a trimethylsilyl-enol-ether is proposed giving rise to a leaving group of trimethyliodosilane and the desired monomethylated product. Deuterated analogues to frequently quantitated ephedrines were readily synthesized with purities >90%, and mass spectra recorded under different ionization and dissociation conditions presented distinct fragmentation processes including eliminations of water and methylamine as well as the generation of a benzyl cation.
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Affiliation(s)
- Mario Thevis
- Institute of Biochemistry, German Sport University Cologne, Carl-Diem Weg 6, 50933 Cologne, Germany. - koeln.de
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85
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Abstract
A sensitive method for the quantification of free salbutamol in human urine is described. Sample clean up is performed using SPE on a mixed phase extraction column. Derivatisation is performed with N-methyl-N-trimethylsilyltrifluoroacetamide (MSTFA) and the extract is analysed by GC-MS. The method was found to be suitable for use in the doping field, where a cut-off limit of 1 microg salbutamol/mL urine is set by the International Olympic Committee (IOC) and approved by the World Anti-Doping Agency (WADA). Above that value a doping violation occurs. In addition, the stability of salbutamol in human urine has been evaluated.
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Affiliation(s)
- Guro Forsdahl
- Doping Control Laboratory, ARC Seibersdorf research GmbH, A-2224 Seibersdorf, Austria
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86
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Khiroug L, Giniatullin R, Klein RC, Fayuk D, Yakel JL. Functional mapping and Ca2+ regulation of nicotinic acetylcholine receptor channels in rat hippocampal CA1 neurons. J Neurosci 2003; 23:9024-31. [PMID: 14534236 PMCID: PMC6740844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
Diverse subtypes of nicotinic acetylcholine receptors (nAChRs), including fast-desensitizing alpha7-containing receptors thought to be Ca2+-permeable, are expressed in the CNS, where they appear to regulate cognitive processing and synaptic plasticity. To understand the physiological role of nAChRs in regulating neuronal excitability, it is important to know the distribution of functional receptors along the surface of neurons, whether they can increase [Ca2+]i, and/or are regulated by Ca2+. We mapped the distribution of receptors on the membrane of rat hippocampal CA1 stratum radiatum interneurons and pyramidal cells in acute slices by recording nAChR-mediated currents elicited by local UV laser-based photolysis of caged carbachol in patch-clamped neurons. The local application (approximately 7 microm patches) allowed mapping of functional nAChRs along the soma and dendritic tree, whereas the fast uncaging minimized the effects of desensitization of alpha7-containing nAChRs and allowed us to measure the kinetics of responses. The alpha7-containing nAChRs were the predominant subtype on interneurons, and were located primarily at perisomatic sites (<70 microm from the soma; in contrast to the more uniform distribution of glutamate receptors); no currents were detectable on pyramidal neurons. The activation of nAChRs increased [Ca2+]i, indicating that these native receptors in acute slices are significantly Ca2+-permeable, consistent with previous observations made with recombinant receptors. In addition, they exhibited strong desensitization, the rate of recovery from which was controlled by [Ca2+]i. Our results demonstrate the strategic location and Ca2+ regulation of alpha7-containing nAChRs, which may contribute to understanding their involvement in hippocampal plasticity.
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Affiliation(s)
- Leonard Khiroug
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
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87
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Abstract
[structure: see text] The widely used internal standard for NMR studies in aqueous solution DSS (sodium 4,4-dimethyl-4-silapentane-1-sulfonate) can interact with cationic peptides, diminishing its value for such studies. This paper introduces DSA (4,4-dimethyl-4-silapentane-1-ammonium trifluoroacetate) as a new internal standard that does not suffer from this problem.
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Affiliation(s)
- James S Nowick
- Department of Chemistry, University of California, Irvine, Irvine, California 92697-2025, USA
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88
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Lee K, Park CW, Jung WH, Park HD, Lee SH, Chung KH, Park SK, Kwon OH, Kang M, Park DH, Lee SK, Kim EE, Yoon SK, Kim A. Efficacious and orally bioavailable thrombin inhibitors based on a 2,5-thienylamidine at the P1 position: discovery of N-carboxymethyl-d-diphenylalanyl-l-prolyl[(5-amidino-2-thienyl)methyl]amide. J Med Chem 2003; 46:3612-22. [PMID: 12904065 DOI: 10.1021/jm030025j] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thrombin, a crucial enzyme in the blood coagulation, has been a target for antithrombotic therapy. Orally active thrombin inhibitors would provide effective and safe prophylaxis for venous and arterial thrombosis. We conducted optimization of a highly efficacious benzamidine-based thrombin inhibitor LB30812 (3, K(i) = 3 pM) to improve oral bioavailability. Of a variety of arylamidines investigated at the P1 position, 2,5-thienylamidine effectively replaced the benzamidine without compromising the thrombin inhibitory potency and oral absorption. The sulfamide and sulfonamide derivatization at the N-terminal position in general afforded highly potent thrombin inhibitors but with moderate oral absorption, while the well-absorbable N-carbamate derivatives exhibited limited metabolic stability in S9 fractions. The present work culminated in the discovery of the N-carboxymethyl- and 2,5-thienylamidine-containing compound 22 that exhibits the most favorable profiles of anticoagulant and antithrombotic activities as well as oral bioavilability (K(i) = 15 pM; F = 43%, 42%, and 15% in rats, dogs, and monkeys, respectively). This compound on a gravimetric basis was shown to be more effective than a low molecular weight heparin, enoxaparin, in the venous thrombosis models of rat and rabbit. Compound 22 (LB30870) was therefore selected for further preclinical and clinical development.
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Affiliation(s)
- Koo Lee
- LG Life Sciences Ltd./R&D Park, P.O. Box 61 Yu-Sung, Science Town, Taejon 305-380, Korea.
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89
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Aime S, Digilio G, Bruno E, Mainero V, Baroni S, Fasano M. Modulation of the antioxidant activity of HO* scavengers by albumin binding: a 19F-NMR study. Biochem Biophys Res Commun 2003; 307:962-6. [PMID: 12878205 DOI: 10.1016/s0006-291x(03)01307-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The interaction between different HO(z.rad;) radical scavengers in a three-component antioxidant system has been investigated by means of 19F-NMR spectroscopy. This system is composed of bovine serum albumin (BSA), trolox, and N-(4-hydroxyphenyl)-trifluoroacetamide (CF(3)PAF). The antioxidant capacity of BSA and trolox has been assessed by measuring the amount of trifluoroacetamide (TFAM) arising from the radical mediated decomposition of CF(3)PAF. When assayed separately, both trolox and BSA behaved as antioxidants, as they were effective to protect CF(3)PAF from HO* radical-mediated decomposition. By contrast, trolox enhanced the production of TFAM in the presence of BSA, thus behaving as a pro-oxidant. Urate, carnosine, glucose, and propylgallate showed antioxidant properties both with or without BSA. CF(3)PAF and trolox were found to bind to BSA with association constants in the order of 5 x 10(3)M(-1) and to compete for the same binding sites. These results have been discussed in terms of BSA-catalysed cross-reactions between trolox-derived secondary radicals and CF(3)PAF.
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Affiliation(s)
- Silvio Aime
- Department of Chemistry I.F.M., University of Torino, Via Pietro Giuria 7, Turin I-10125, Italy
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90
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Kress M, Meissner D, Kaiser P, Hanke R, Wood WG. The measurement of theophylline in human serum or plasma using gas chromatography and isotope dilution-mass spectrometry (GC-IDMS) taking other substituted xanthines into consideration. Clin Lab 2003; 48:535-40. [PMID: 12389715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
A method is described which uses a combination of gas chromatography and isotope dilution-mass spectrometry (GC-IDMS) to determine the concentration of theophylline (1,3-dimethyl xanthine) in human plasma or serum samples. The effects of similar substituted xanthines - namely theobromine (3,7-dimethyl xanthine), paraxanthine (1,7-dimethyl xanthine) 1,3-dimethyl-7-(2-hydroxyethyl) xanthine (internal standard HPLC) and caffeine (1,3,7-trimethyl xanthine) were tested to confirm the specificity of the method. The derivatisation of all xanthines was performed with N-methyl-N-trimethylsilyl trifluroacetamide (MSTFA). The internal standard used was 2-(13)C ,1,3-(15)N2-theophylline. The extraction and derivatisation procedures were examined in detail and optimised stepwise during the development of the method. High-performance liquid chromatography (HPLC) was used for comparison.
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Affiliation(s)
- Michael Kress
- Instand Reference Laboratories Instand e.V., Düsseldorf, Germany
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91
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Kanamori K, Kondrat RW, Ross BD. 13C enrichment of extracellular neurotransmitter glutamate in rat brain--combined mass spectrometry and NMR studies of neurotransmitter turnover and uptake into glia in vivo. Cell Mol Biol (Noisy-le-grand) 2003; 49:819-36. [PMID: 14528919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
13C-enrichment analysis of glutamate in the extracellular fluid (GLU(ECF): 2-3 microM) by gas-chromatography/mass-spectrometry (GCMS) was combined with in vivo NMR observation of whole-brain GLU (approximately10 mM) to study neurotransmitter uptake. Brain GLU C5 was 13C-enriched by intravenous [2,5-13C]glucose infusion. GLU(ECF) was collected by microdialysis from the cortico-striatal region of awake rats. The 13C-enrichment of basal dialysate GLU C5 during 0.75-1.25 hr of infusion was 0.263 +/- 0.01, very close to the enrichment of whole-brain GLU C5. The result strongly suggests that dialysate GLU consists predominantly of neurotransmitter GLU. For selective 13C-enrichment of neurotransmitter GLU, the whole-brain 13C-enrichment was followed by [12C]glucose infusion to chase 13C from the small glial GLU pool. This leaves [5-13C]GLU mainly in the large neuronal metabolic pool and the vesicular neurotransmitter pool. The uptake of synaptic [5-13C]GLU(ECF) into glia and metabolism to glutamine (GLN) were monitored in vivo by NMR observation of [5-13C,15N]GLN formed during 15NH4Ac infusion. The rate of GLN synthesis, derived from neurotransmitter GLU(ECF) (which provided 80-90% of the substrate) was 6.4 +/- 0.44 micromol/g/hr. Hence, the observed rate represents a reasonable estimate for the rate of glial uptake of GLU(ECF), a process that is crucial for protecting the brain from GLU excitotoxicity.
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Affiliation(s)
- K Kanamori
- Magnetic Resonance Spectroscopy Laboratory, Huntington Medical Research Institutes, 660 S. Fair Oaks, Pasadena, CA 91105, USA.
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92
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Hochlowski J, Cheng X, Sauer D, Djuric S. Studies of the relative stability of TFA adducts vs non-TFA analogues for combinatorial chemistry library members in DMSO in a repository compound collection. J Comb Chem 2003; 5:345-9. [PMID: 12857099 DOI: 10.1021/cc0300107] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jill Hochlowski
- Abbott Laboratories, 100 Abbott Park Road, Abbott Park, Illinois, 60064, USA
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93
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TERNER C. The metabolism of citric acid in the mammary gland. 2. The effect of p-nitrophenol and of fluoride on the synthesis of citric acid in fluoroacetate-blocked homogenates. Biochem J 2003; 60:95-101. [PMID: 14363190 PMCID: PMC1215658 DOI: 10.1042/bj0600095] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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94
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Lerch O, Zinn P. Derivatisation and gas chromatography-chemical ionisation mass spectrometry of selected synthetic and natural endocrine disruptive chemicals. J Chromatogr A 2003; 991:77-97. [PMID: 12703903 DOI: 10.1016/s0021-9673(03)00175-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Methods for ultra trace detection of endocrine disruptive chemicals (EDCs) are needed because of their low levels of impact. Twenty-one EDCs were selected, including 17beta-estradiol, 17alpha-ethinylestradiol, 17beta-testosterone and bisphenol A. Derivatisation with eight different fluorine containing compounds was examined. All EDCs could be derivatised automatedly (autosampler) with heptafluorobutyric acid (HFB) anhydride and trifluoroacetic acid (TFA) anhydride, respectively. The detection of these HFB and TFA derivatives in different chemical ionisation modes was studied. Fourteen different reagent gases, including methane, ammonia, acetone and water, were tested with the HFB and TFA derivatives in the negative chemical ionisation mode. Furthermore both types of derivatives were measured in positive chemical ionisation mode. Methane or water provide a good detection of all 21 TFA derivatives and create mass spectra with few fragmentation and characteristic mass peaks. This could serve as a basis for tandem or multiple mass spectrometric measurements.
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Affiliation(s)
- Oliver Lerch
- Department of Analytical Chemistry, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany.
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95
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Abstract
Substitution of native amino acids by fluoroalkyl analogues represents a new approach for the design of biologically active peptides with increased metabolic stability as well as defined secondary structure and provides a powerful label for spectroscopic investigations. Here, we introduce a methodology for the incorporation of sterically demanding C(alpha)-fluoroalkyl amino acids into the P(1) position of peptides catalyzed by the commercially available proteases trypsin and alpha-chymotrypsin. The combination of 4-guanidinophenyl ester of C(alpha)-fluoroalkyl amino acids as substrate mimetics with frozen-state reaction conditions provided the most efficient strategy for protease-catalyzed site-specific introduction of this kind of nonnatural amino acids into peptide sequences. Consequently, a library of di-, tri-, and tetrapeptides containing alpha-methyl, alpha-difluoromethyl, and alpha-trifluoromethyl alanine, leucine, and phenylalanine in the P(1) position was synthesized catalyzed by trypsin as well as alpha-chymotrypsin. Trypsin was shown to be the more versatile protease.
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Affiliation(s)
- Sven Thust
- Department of Organic Chemistry, University of Leipzig, Germany
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96
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Kondrat RW, Kanamori K, Ross BD. In vivo microdialysis and gas-chromatography/mass-spectrometry for 13C-enrichment measurement of extracellular glutamate in rat brain. J Neurosci Methods 2002; 120:179-92. [PMID: 12385768 DOI: 10.1016/s0165-0270(02)00201-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Extracellular glutamate (GLU(ECF)) was collected by microdialysis from the corticostriatal region of awake rats, at the basal level and after elevation by perfusion of GLU uptake inhibitor, L-trans-pyrrolidine-2,4-dicarboxylic acid. Concurrently, [2,5-(13)C]glucose was infused intravenously to 13C-enrich brain GLU predominantly at C5. The 13C enrichment of GLU(ECF) was measured, after tert-butyldimethylsilylation, by gas-chromatography/mass-spectrometry. Excellent signal-to-noise ratios of the analyte signals at three selected ion-pairs were achieved at approximately 20 pmol. The fractional 13C enrichment of basal dialysate GLU C5, collected during 0.75-1.25 h of [2,5-(13)C]glucose infusion, was 0.263+/-0.01, very close to the enrichment of whole-brain (predominantly intracellular) GLU C5 measured in parallel NMR study. The result strongly suggests that the dialysate GLU consists predominantly of neurotransmitter GLU, which was 13C-enriched in, and released from, neurons by exocytosis and had diffused to the dialysis probe; the label is undiluted by 12C-GLU(ECF) present before the enrichment. Hence, our result supports the view, proposed on the basis of Ca(2+)- and tetrodotoxin-sensitivity of dialysate GLU, that basal dialysate GLU in awake non-stimulated brain mainly represents neurotransmitter GLU. Isotope labeling provides a novel method for determining the extent to which dialysate GLU reflects synaptic GLU(ECF), and for measuring its turnover under physiological or pathological conditions.
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Affiliation(s)
- Richard W Kondrat
- Mass Spectrometry Facility, University of California, Riverside, CA, USA
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97
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Affiliation(s)
- Motonobu Nakamura
- Department of Dermatology, Graduate School of Medicine, Kyoto University, Japan.
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98
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Abstract
We describe a case of massive hemorrhage in the cerebral ventricles, probably caused by methamphetamine abuse. A 44-year-old male was found dead in a prone position in a hotel room. Old and new injection marks were observed in his right cubital fossa. Petechiae were observed on the conjunctiva of his right eye, laryngeal mucosa, epicardium and under the capsule of the liver (to a slight or moderate degree). The brain, weighing 1.67 kg, was heavily edematous; the lateral and fourth ventricles were filled with hematomas. Subarachnoid, intracerebral hemorrhages were not observed. Cerebral vascular abnormalities were not evident. There were no remarkable changes in other organs, other than congestion. Gas chromatographic-mass spectrometric analysis of the urine disclosed the presence of methamphetamine and amphetamine. The concentration of methamphetamine within the femoral venous blood and intraventricular hematoma was 0.347 microg/ml and 0.189 microg/g, respectively. Amphetamine was not detected in either sample. Urine contained 3.15 microg/ml methamphetamine and 0.063 microg/ml amphetamine. These results indicate that intraventricular hemorrhage might have occurred shortly after intravenous self-administration of methamphetamine. Cerebral arterial spasm and hypertension resulting from the administration of methamphetamine might have resulted in intraventricular hemorrhage.
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Affiliation(s)
- Fumio Moriya
- Department of Legal Medicine, Kochi Medical School, Kohasu, Oko-cho, Nankoku City, Japan.
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99
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Abstract
A new efficient synthesis of GDP-hexanolamine from hexanolamine is reported with an overall yield of 71%. The pyrophosphate formation, the key step of this preparation, was achieved through a sequential GMP activation procedure based on polytrifluoroacetylation of GMP followed by activation of the phosphate group by 1-methylimidazole.
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Affiliation(s)
- Stéphane P Vincent
- Laboratoire des Processus Sélectifs en Chimie Organique et Bioorganique, Département de Chimie, UMR 8642 du CNRS, Ecole Normale Supérieure, 24 rue Lhomond, F-75231 Paris, France.
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100
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Abstract
This paper describes the discovery of alpha-trifluoroketoacetamides as potent antibacterial agents against Gram-positive organisms. The initial SAR indicates that the aryl ethyl side chain is essential in maintaining antibacterial activity. The SAR observations have been utilized to design a bioisostere for the alpha-trifluoroketoacetamide with good activity against Gram-positive organisms.
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Affiliation(s)
- A Thorarensen
- Department of Medicinal Chemistry, Pharmacia, 7254-209-615, Kalamazoo, MI 49007-4940, USA.
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