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1.
Rev. parag. reumatol ; 9(2)dic. 2023.
Article in Spanish | LILACS-Express | LILACS | ID: biblio-1536683

ABSTRACT

La fiebre Chikungunya es causada por un arbovirus ARN perteneciente a la familia Togaviridae del género alphavirus, llamado "virus del chikungunya", este virus tiene como vector el Aedes aegypti y el Aedes albopictus. En su fase aguda la enfermedad se manifiesta por fiebre, artritis o artralgias severas, mialgias, cefalea, fotofobia, linfadenopatías y brotes cutáneos, los síntomas pueden progresar a una fase subaguda hasta crónica, donde persisten las manifestaciones articulares y la fatiga. Se realizó una revisión sistemática en las bases de PubMed, Cochrane, Dovepress y SciELO, utilizando las palabras claves: chikungunya y chikunguña, cruzadas con las palabras: artritis crónica y tratamiento. Se incluyeron en el estudio un total de 16 artículos, 6 artículos de revisión, 4 artículos originales, 2 ensayos clínicos, 2 reportes de caso, 1 revisión sistemática y 1 carta al editor. Entre las opciones farmacológicas, el metotrexato es el fármaco más estudiado y compite con los efectos de los AINE. Como terapias no farmacológicas se encuentran la fisioterapia y la terapia física, utilizados como complementos a la terapia farmacológica. El uso de terapias caseras, incluso la homeopatía, también podrían agregarse, atendiendo principalmente el factor psíquico y cultural de los pacientes.


Chikungunya fever is caused by an RNA arbovirus belonging to the Togaviridae family of the alphavirus genus, called "chikungunya virus", this virus is vectored by Aedes aegypti and Aedes albopictus. In its acute phase, the disease is manifested by fever, arthritis or severe arthralgia, myalgia, headache, photophobia, lymphadenopathy and skin rashes. The symptoms can progress to a subacute to chronic phase, where joint manifestations and fatigue persist. A bibliographic search was carried out in the PubMed, Cochrane, Dovepress and SciELO databases, using the keywords: chikungunya and chikunguña, crossed with the words: chronic arthritis and treatment. A total of 16 articles were included: 6 review articles, 1 systematic review, 4 original articles, 2 clinical trials, 1 letter to Editor letter and 2 case reports. Among the pharmacological options, methotrexate is the most studied drug and competes with the effects of NSAIDs. Non-pharmacological therapies are physiotherapy and physical therapy, used as complements to pharmacological therapy. The use of home therapies, including homeopathy, could also be added, mainly addressing the psychological and cultural factors of the patients.

2.
Chempluschem ; 88(10): e202300384, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37721529

ABSTRACT

Certified reference materials (CRM) of amphetamine derivatives were produced through a simple, rapid and efficient synthesis in both batch and continuous-flow conditions, accompanied by the development of a comprehensive certification protocol for this class of substances. Our chemistry enabled the synthesis of MDA, MDMA, PMA and PMMA in two steps from safrole and estragole with overall yields of 38-61 % in 48 hours under batch conditions and 61-65 % in 65 minutes under continuous-flow conditions, followed by the development of a certification protocol for these materials through identity checking, homogeneity, stability, and characterization studies. Furthermore, as result of this work, a very pure CRM of MDA.HCl with 99.1±1.4 g/100 g of certified characterization value was produced. Considering the importance of supplying amphetamine calibrants for public security efforts in Forensic Chemistry, the potential therapeutical applications, and responding to the rising demand for the synthesis of CRM, this work presents a pioneering approach for the production of amphetamine and related compounds.

3.
Drug Test Anal ; 15(1): 66-74, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36093901

ABSTRACT

The estimation of limits of detection (LOD) for solely qualitative methods in analytical chemistry may prove challenging because all the approaches with which chemists are familiar require some type of numeric data input. The best model to describe the binary response in these methods (detected/not detected) is a logistic model; however, these models are not easily handled by most of the laboratories and generally demand expensive statistical software packages. In this work, the advantages of applying this approach are discussed and its implementation using commercial spreadsheet software is demonstrated. A free online application based on the R environment using shinyapps was developed and its application was validated and discussed with a dataset of 57 different target compounds analyzed in urine according to the requirements of the World Anti-Doping Agency (WADA). This tool allows free, extremely quick, and easy determinations of LOD in qualitative analyses as well as the determination of the probabilities of detection in any given concentration.


Subject(s)
Doping in Sports , Tandem Mass Spectrometry , Limit of Detection , Tandem Mass Spectrometry/methods , Logistic Models , Internet
4.
Phytochem Anal ; 34(1): 48-55, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36191930

ABSTRACT

INTRODUCTION: Data Fusion-based Discovery (DAFdiscovery) is a pipeline designed to help users combine mass spectrometry (MS), nuclear magnetic resonance (NMR), and bioactivity data in a notebook-based application to accelerate annotation and discovery of bioactive compounds. It applies Statistical Total Correlation Spectroscopy (STOCSY) and Statistical HeteroSpectroscopy (SHY) calculation in their data using an easy-to-follow Jupyter Notebook. METHOD: Different case studies are presented for benchmarking, and the resultant outputs are shown to aid natural products identification and discovery. The goal is to encourage users to acquire MS and NMR data from their samples (in replicated samples and fractions when available) and to explore their variance to highlight MS features, NMR peaks, and bioactivity that might be correlated to accelerated bioactive compound discovery or for annotation-identification studies. RESULTS: Different applications were demonstrated using data from different research groups, and it was shown that DAFdiscovery reproduced their findings using a more straightforward method. CONCLUSION: DAFdiscovery has proven to be a simple-to-use method for different situations where data from different sources are required to be analyzed together.


Subject(s)
Biological Products , Magnetic Resonance Spectroscopy/methods , Mass Spectrometry/methods
5.
Phytochem Anal ; 33(4): 533-542, 2022 Jun.
Article in English | MEDLINE | ID: mdl-35098600

ABSTRACT

INTRODUCTION: In this era of 'omics' technology in natural products studies, the complementary aspects of mass spectrometry (MS)- and nuclear magnetic resonance (NMR)-based techniques must be taken into consideration. The advantages of using both analytical platforms are reflected in a higher confidence of results especially when using replicated samples where correlation approaches can be used to statistically link results from MS to NMR. OBJECTIVES: Demonstrate the use of Statistical Total Correlation (STOCSY) for linking results from MS and NMR data to reach higher confidence in compound identification. METHODOLOGY: Essential oil samples of Melaleuca alternifolia and M. rhaphiophylla (Myrtaceae) were used as test objects. Aliquots of 10 samples were collected for GC-MS and NMR data acquisition [proton (1 H)-NMR, and carbon-13 (13 C)-NMR as well as two-dimensional (2D) heteronuclear single quantum correlation (HSQC), heteronuclear multiple-bond correlation (HMBC), and HSQC-total correlated spectroscopy (TOCSY) NMR]. The processed data was imported to Matlab where STOCSY was applied. RESULTS: STOCSY calculations led to the confirmation of the four main constituents of the sample-set. The identification of each was accomplished using; MS spectra, retention time comparison, 13 C-NMR data, and scalar correlations of the 2D NMR spectra. CONCLUSION: This study provides a pipeline for high confidence in compound identification using a set of essential oils samples as test objects for demonstration.


Subject(s)
Metabolomics , Oils, Volatile , Magnetic Resonance Spectroscopy/methods , Mass Spectrometry , Metabolomics/methods , Pilot Projects
6.
Anal Bioanal Chem ; 413(6): 1701-1714, 2021 Mar.
Article in English | MEDLINE | ID: mdl-33501553

ABSTRACT

Comparability of measurement results and their metrological traceability to the International System of Units (SI) are fundamental tools to ensure reliable decisions in the social sphere, commerce, and science. The use of appropriate references in analytical chemistry, such as certified reference materials (CRMs) of high purity substances, is one of the required procedures to obtain traceable measurements. When commercial standards with non-certified purity values are used, traceability must be achieved by determining the purity of the standard using a potential primary reference measurement procedure or other appropriate methods. Quantitative nuclear magnetic resonance (qNMR) is a technique with the potential to be used in primary measurement procedures. This work presents the determination of purity by 1H qNMR for nitrofuran metabolites 3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), and 1-aminohydantoin (AHD). Furthermore, a recent qNMR method developed by our group to improve the quantitative performance of measurements using 13C nucleus was used to determine the purity of semicarbazide (SEM) nitrofuran metabolite. Purity values obtained by qNMR for AOZ, AMOZ, and AHD standards were compared to values obtained by the mass balance approach using a suite of analytical methods: Karl Fischer (KF) coulometric titration and thermogravimetry (TG) for the determination of water and residual solvents, gas and liquid chromatography for the determination of impurities structurally related to the metabolites. The results obtained by qNMR and mass balance were consistent.Graphical abstract.

7.
J AOAC Int ; 102(6): 1740-1748, 2019 Nov 01.
Article in English | MEDLINE | ID: mdl-31492203

ABSTRACT

Background: The contamination of food and feed by mycotoxins, Aflatoxin B1 (AfB1) being one of the most prominent examples, is of imminent concern to many countries. Regulatory limits for mycotoxins have been implemented, and these need to be supported by a sound measurement infrastructure for mycotoxin analysis in order to enforce and verify products, protect populations, and avoid technical barriers to trade in food stuffs. Objective: A Capability Building and Knowledge Transfer program on Metrology for Safe Food and Feed in Developing Economies was started at the International Bureau of Weights and Measures to allow National Metrology Institutes or Designated Institutes to work together to strengthen their national mycotoxin metrology infrastructure. Methods: Knowledge transfer to scientists is provided to enable the characterization of selected pure mycotoxin materials and the production of corresponding certified reference material solutions. Results: This higher-order measurement capability can in turn support mycotoxin testing laboratories within their countries through the provision, for example, of standard solutions of critical analytes that are traceable to the International System of Units (SI). Conclusions and Highlights: The purity characterization and value assignment for a high-purity AfB1 material (979.6 ± 2.3 mg/g, k = 2) intended to be used for the gravimetric production of SI traceable calibration solutions for AfB1 is described using an approach combining quantitative NMR and LC-diode array detection-tandem MS for the correction of the mycotoxin-related impurity content.


Subject(s)
Aflatoxin B1/analysis , Calibration , Chromatography, Liquid , International Cooperation , Proton Magnetic Resonance Spectroscopy , Reference Standards , Tandem Mass Spectrometry
8.
J. Bras. Patol. Med. Lab. (Online) ; 55(4): 402-411, July-Aug. 2019. graf
Article in Portuguese | LILACS-Express | LILACS | ID: biblio-1019954

ABSTRACT

RESUMO Os resultados da medicina laboratorial influenciam uma alta porcentagem das decisões tomadas pelos médicos. A globalização requer que os resultados obtidos por métodos diferentes sejam concordantes, garantindo a segurança do paciente. É necessário haver colaboração internacional para difundir essa exigência. Essa colaboração deve basear-se na rastreabilidade da medicina laboratorial, bem como na adoção de procedimentos de medição e materiais de referência de alta hierarquia metrológica e que sejam comutáveis internacionalmente. A aplicação da cadeia de rastreabilidade metrológica facilita essa abordagem universal. A quantificação de colesterol no soro e Hemoglobina sanguínea A1c (HbA1c) no sangue serve como exemplo do processo de padronização de métodos com impacto demonstrado nos resultados clínicos. Por outro lado, a quantificação de paratormônio (PTH) e hemoglobina A2 (HbA2) no sangue revela a variabilidade entre os métodos atualmente em uso, que compromete o tratamento do paciente e demanda, portanto, a harmonização e/ou padronização dos métodos. Os desafios à difusão da rastreabilidade em medicina laboratorial incluem fatores como disponibilidade de materiais e métodos de referência, diferenças geográficas, uso de unidades de medida variadas, ensaios de analitos complexos e coordenação mundial limitada. Uma colaboração abrangente requer o envolvimento das partes interessadas no âmbito mundial, desde especialistas gerais a aqueles com particular experiência em medicina laboratorial, com vivência em laboratórios clínicos de rotina. Um plano de coordenação é apresentado neste artigo com ações atribuídas a cada um dos envolvidos.


ABSTRACT Laboratory medicine results influence a high percentage of all clinical decisions. Globalization requires that laboratory medicine results should be transferable between methods in the interests of patient safety. International collaboration is necessary to deliver this requirement. That collaboration should be based on traceability in laboratory medicine and the adoption of higher order international commutable reference materials and measurement procedures. Application of the metrological traceability chain facilitates a universal approach. The measurement of serum cholesterol and blood HbA1c serve as examples of the process of method standardization where an impact on clinical outcomes is demonstrable. The measurement of plasma parathyroid hormone and blood HbA2 serve as examples where the current between method variability is compromising patient management and method standardization and/or harmonization is required. Challenges to the widespread adoption of traceability in laboratory medicine include the availability of reference materials and methods; geographical differences; the use of variable units; complex analytes and limited global coordination. The global collaboration requires the involvement of several different stakeholder groups ranging from international experts to laboratory medicine specialists in routine clinical laboratories. A coordinated action plan is presented with actions attributable to each of these stakeholder groups.

9.
J Proteomics ; 147: 48-55, 2016 09 16.
Article in English | MEDLINE | ID: mdl-27072112

ABSTRACT

UNLABELLED: The growing consumption of nutritional supplements might represent a problem, given the concern about the quality of these supplements. One of the most used supplements is whey protein (WP); because of its popularity, it has been a target of adulteration with substitute products, such as cheaper proteins with lower biological value. To investigate this type of adulteration, this study used shotgun proteomics analyses by MS(E) (multiplexed, low- and high-collision energy, data-independent acquisition) of WP-based supplements. Seventeen WP-based supplement samples were evaluated. Chicken, maize, rice, potato, soybean, and wheat proteins were considered as probable sources of bovine whey adulteration. Collectively, 523 proteins were identified across all 16 samples and replicates, with 94% of peptides inside a normal distribution within 10ppm of maximum error. In 10 of the 16 samples analyzed, only proteins from bovine whey could be detected, while in the other samples several other protein sources were detected in high concentrations, especially soybean, wheat, and rice. These results point out a probable adulteration and/or sample contamination during manufacturing that could only be detected using this proteomic approach. SIGNIFICANCE: The present work shows how shotgun proteomics can be used to provide reliable answers in quality control matters, especially focusing on Whey Protein nutritional supplements which are a very popular subject in food and nutrition. In order to achieve an appropriate methodology, careful evaluation was performed applying extremely rigorous quality criteria, established for the proteomic analysis. These criteria and the methodological approach used in this work might serve as a guide for other authors seeking to use proteomics in quality control.


Subject(s)
Dietary Supplements/standards , Whey Proteins/analysis , Animals , Cattle , Food Contamination/analysis , Mass Spectrometry , Proteomics/methods , Quality Control , Whey Proteins/standards
10.
Magn Reson Chem ; 53(2): 135-41, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25303142

ABSTRACT

Quantitative nuclear magnetic resonance measurements have become more popular over the last decade. The introduction of new methods and experimental parameters has been of fundamental importance in the development of new applications. Amongst these new developments is the introduction of electronic referencing for quantifications. The use of electronic referencing eliminates errors in the analyses as a result of weighting of internal standards as well as undesired problems as a result of the solubility of the standards in the analyte solution and chemical interactions between the analyte and the internal standard. In this work, we have studied the quantification of a very important analyte in a food matrix, benzoic acid in orange juice, as a model to the validation and measurement uncertainty estimation of electronic referencing using (1)H NMR in food analyses. The referencing method applied was the pulse length-based concentration measurement. Method was validated and showed good results for the precision and accuracy parameters evaluated. A certified reference material and a reference material candidate were analyzed, and extremely good results were obtained. Reported relative expanded uncertainties are in the 1.07-1.39% range that can be considered an extremely good performance for the analysis of a food complex matrix. Measurement uncertainty was evaluated by two different approaches, and the pulse calibrations for the samples and for the reference have been shown to account for approximately 80% of the total uncertainty of the measurement.

11.
Biomed Chromatogr ; 27(12): 1630-8, 2013 Dec.
Article in English | MEDLINE | ID: mdl-23801106

ABSTRACT

Salbutamol is commonly used in asthma treatment, being considered a short-effect bronchodilator. This drug poses special interest in certain fields of chemical analysis, such as food, clinical and doping analyses, in which it needs to be analyzed with quantitative precision and accuracy. Salbutamol, however, is known to degrade under certain conditions and this is critical if quantitative results must be generated. The present work aimed to investigate salbutamol extraction from urine samples, to determine whether salbutamol is unstable in other solvents as well as in urine samples, to elucidate the structures of the possible degradation products and to validate an analytical method using the extraction procedure evaluated. Stability investigations were performed in urine at different pH values, in methanol and acetone at different temperatures. Semi-preparative liquid chromatography was performed for the isolation of degradation products, and gas chromatography coupled to mass spectrometry as well as nuclear magnetic resonance were used for identification. Three unreported methylation products were detected in methanolic solutions and had their structures elucidated. Urine samples showed a reduction in salbutamol concentration of up to 25.8% after 5 weeks. These results show that special care must be taken regarding salbutamol quantitative analyses, since degradation either in standard solutions or in urine could lead to incorrect values.


Subject(s)
Albuterol/chemistry , Albuterol/urine , Albuterol/isolation & purification , Chemical Fractionation , Drug Stability , Gas Chromatography-Mass Spectrometry/methods , Humans , Hydrogen-Ion Concentration , Methylation , Reproducibility of Results , Sensitivity and Specificity
12.
Steroids ; 78(2): 228-33, 2013 Feb.
Article in English | MEDLINE | ID: mdl-23200734

ABSTRACT

The use of "nutritional supplements" containing unapproved substances has become a regular practice in amateur and professional athletes. This represents a dangerous habit for their health once no data about toxicological or pharmacological effects of these supplements are available. Most of them are freely commercialized online and any person can buy them without medical surveillance. Usually, the steroids intentionally added to the "nutritional supplements" are testosterone analogues with some structural modifications. In this study, the analyzed product was bought online and a new anabolic steroid known as methylstenbolone (2,17α-dimethyl-17ß-hydroxy-5α-androst-1-en-3-one) was detected, as described on label. Generally, anabolic steroids are extensively metabolized, thus in-depth knowledge of their metabolism is mandatory for doping control purposes. For this reason, a human excretion study was carried out with four volunteers after a single oral dose to determine the urinary metabolites of the steroid. Urine samples were submitted to enzymatic hydrolysis of glucuconjugated metabolites followed by liquid-liquid extraction and analysis of the trimethylsilyl derivatives by gas chromatography coupled to tandem mass spectrometry. Mass spectrometric data allowed the proposal of two plausible metabolites: 2,17α-dimethyl-16ξ,17ß-dihydroxy-5α-androst-1-en-3-one (S1), 2,17α-dimethyl-3α,16ξ,17ß-trihydroxy-5α-androst-1-ene (S2). Their electron impact mass spectra are compatible with 16-hydroxylated steroids O-TMS derivatives presenting diagnostic ions such as m/z 231 and m/z 218. These metabolites were detectable after one week post administration while unchanged methylstenbolone was only detectable in a brief period of 45 h.


Subject(s)
Androstenols/metabolism , Androstenols/urine , Chromatography, Gas/methods , Designer Drugs/analysis , Dietary Supplements/analysis , Steroids/urine , Tandem Mass Spectrometry/methods , Adult , Androstenols/administration & dosage , Androstenols/chemistry , Humans , Kinetics , Male , Steroids/administration & dosage , Steroids/chemistry , Steroids/metabolism , Time Factors
13.
Eur J Pharm Sci ; 48(3): 502-13, 2013 Feb 14.
Article in English | MEDLINE | ID: mdl-23220339

ABSTRACT

Certified reference materials (CRMs) are essential tools to guarantee the metrological traceability of measurement results to the International System of Units (SI), which means the accuracy and comparability of results over time and space. In the pharmaceutical area, only a few CRMs are available and the use of (non-certified) reference materials is a much more common practice. In this paper, the studies on a new candidate CRM of sodium diclofenac based on the ISO Guides 34:2009 and 35:2005 are described. The project steps included characterization, homogeneity test, stability studies, and uncertainties estimation. In the characterization, the mass fractions of organic, inorganic, and volatile impurities were determined, and the results were cross-checked by independent reference methods or interlaboratorial study. The API mass fraction was calculated by mass balance and cross-checked by quantitative proton nuclear magnetic resonance (¹H qNMR). The paper also presents a Monte Carlo simulation to estimate the measurement uncertainty as an approach to validate the GUM results in ¹H qNMR. The homogeneity between batch units was verified, and the candidate CRM stability under transport and storage conditions was evaluated in short- and long-term stability studies. The CRM certified property value and corresponding expanded uncertainty, obtained from the combined standard uncertainty multiplied by the coverage factor (k=2), for a confidence level of 95%, was (999.76+0.10) mg g⁻¹.


Subject(s)
Diclofenac/analysis , Models, Molecular , Brazil , Chromatography, High Pressure Liquid , Diclofenac/chemistry , Diclofenac/isolation & purification , Diclofenac/standards , Drug Contamination , Drug Stability , Drug Storage , Guidelines as Topic , International System of Units , Limit of Detection , Monte Carlo Method , Proton Magnetic Resonance Spectroscopy , Quality Control , Reference Standards , Reproducibility of Results , Spectrophotometry, Ultraviolet , Technology, Pharmaceutical , Transportation , Uncertainty
14.
J Steroid Biochem Mol Biol ; 127(3-5): 248-54, 2011 Nov.
Article in English | MEDLINE | ID: mdl-21924357

ABSTRACT

Exemestane is an irreversible aromatase inhibitor used for anticancer therapy. Unfortunately, this drug is also misused in sports to avoid some adverse effects caused by steroids administration. For this reason exemestane has been included in World Anti-Doping Agency prohibited list. Usually, doping control laboratories monitor prohibited substances through their metabolites, because parent compounds are readily metabolized. Thus metabolism studies of these substances are very important. Metabolism of exemestane in humans is not clearly reported and this drug is detected indirectly through analysis of its only known metabolite: 17ß-hydroxyexemestane using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) and gas chromatography coupled to mass spectrometry (GC-MS). This drug is extensively metabolized to several unknown oxidized metabolites. For this purpose LC-MS/MS has been used to propose new urinary exemestane metabolites, mainly oxidized in C6-exomethylene and simultaneously reduced in 17-keto group. Urine samples from four volunteers obtained after administration of a 25mg dose of exemestane were analyzed separately by LC-MS/MS. Urine samples of each volunteer were hydrolyzed followed by liquid-liquid extraction and injected into a LC-MS/MS system. Three unreported metabolites were detected in all urine samples by LC-MS/MS. The postulated structures of the detected metabolites were based on molecular formulae composition obtained through high accuracy mass determination by liquid chromatography coupled to hybrid quadrupole-time of flight mass spectrometry (LC-QTOF MS) (all mass errors below 2ppm), electrospray (ESI) product ion spectra and chromatographic behavior.


Subject(s)
Androstadienes/metabolism , Aromatase Inhibitors/metabolism , Chromatography, Liquid/methods , Spectrometry, Mass, Electrospray Ionization/methods , Substance Abuse Detection/methods , Tandem Mass Spectrometry/methods , Adult , Androstadienes/urine , Aromatase Inhibitors/urine , Doping in Sports , Humans , Male
15.
Steroids ; 76(10-11): 1010-5, 2011.
Article in English | MEDLINE | ID: mdl-21530565

ABSTRACT

Exemestane is an aromatase enzyme complex inhibitor. Its metabolism in humans is not fully described and there is only one known metabolite: 17ß-hydroxyexemestane. In this work, excretion studies were performed with four volunteers aiming at the detection of new exemestane metabolites in human urine by gas chromatography coupled to mass spectrometry (GC-MS) after enzymatic hydrolysis and liquid-liquid extraction. Urine samples collected from four volunteers were analyzed separately. The targets of the study were mainly the 6-exomethylene oxidized metabolites. Two unreported metabolites were identified in both free and glucuconjugated urine fractions from all four volunteers, both of them were the result of the 6-exomethylene moiety oxidation: 6ξ-hydroxy-6ξ-hydroxymethylandrosta-1,4-diene-3,17-dione (metabolite 1) and 6ξ-hydroxyandrosta-1,4-diene-3,17-dione (metabolite 2). Furthermore, only in glucoconjugated fractions from all volunteers, one metabolite arising from the A-ring reduction was identified as well, 3ξ-hydroxy-5ξ-androst-1-ene-6-methylene-17-one (metabolite 3). The molecular formulae of all these metabolites were ascertained by the determination of exact masses using gas chromatography coupled to high resolution mass spectrometry (GC-HRMS). Moreover, all metabolites were confirmed using an alternative derivatization with methoxyamine and MSTFA/TMS-imidazole.


Subject(s)
Androstadienes/urine , Gas Chromatography-Mass Spectrometry/methods , Adult , Humans , Male , Molecular Structure , Young Adult
16.
Rapid Commun Mass Spectrom ; 24(22): 3297-302, 2010 Nov 30.
Article in English | MEDLINE | ID: mdl-20973004

ABSTRACT

Trimethylsilylation of anabolic agents and their metabolites is frequently achieved by using the derivatization mixture N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA)/NH(4)I/2-mercaptoethanol. Nevertheless, artifacts were formed when this mixture was employed in the monitoring of exemestane and its main metabolite 17ß-hydroxyexemestane prior to GC-MS analysis. These artifacts were identified as the N-methyltrifluoroacetamide (MTFA) and trimethylsiloxyethylmercapto products of the respective trimethylsilyl (TMS) derivatives. Furthermore, artifact formation was evaluated taking the structure (1,4-diene-3-keto-6-exomethylene) of the compounds into account. Although these artifacts are relevant for investigations regarding the derivatization process and may be of interest in many fields, they are detrimental to cope with the requirements of the World Anti-Doping Agency (WADA) in terms of the limits of detection (LODs) required. To overcome this issue, a method using an alternative derivatization was proposed: formation of methyloxime-TMS derivatives through double derivatization using O-methylhydroxylamine/pyridine and MSTFA/TMS imidazole after enzymatic hydrolysis and liquid-liquid extraction. Samples from an excretion study after administration of exemestane to healthy volunteers were analyzed by the proposed method and detection of both exemestane and its main metabolite was possible. This method showed excellent results for both analytes meeting the LODs required for antiestrogenic agents (50 ng/mL) established by WADA. The method was validated for the main metabolite, it was robust and cost-effective for qualitative and quantitative purposes, with LOD and LOQ of 10 ng/mL and 25 ng/mL, respectively.


Subject(s)
Androstadienes/urine , Gas Chromatography-Mass Spectrometry/methods , Acetamides , Adult , Androstadienes/chemistry , Androstadienes/pharmacokinetics , Artifacts , Doping in Sports , Fluoroacetates , Humans , Male , Oximes/chemistry , Reproducibility of Results , Sensitivity and Specificity , Trifluoroacetic Acid/chemistry , Trimethylsilyl Compounds/chemistry
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