Analysis of selected designer benzodiazepines by ultra high performance liquid chromatography with high‐resolution time‐of‐flight mass spectrometry and the estimation of their partition coefficients by micellar electrokinetic chromatography

A new ultra high performance liquid chromatography with electrospray ionization time of flight mass spectrometry method for the selective and sensitive separation, identification, and determination of selected designer benzodiazepines (namely, pyrazolam, phenazepam, etizolam, flubromazepam, diclazepam, deschloroetizolam, bentazepam, nimetazepam, and flubromazolam) in human serum was developed. The separation of the studied designer benzodiazepines was achieved on C₁₈ chromatographic column using gradient elution within 6 min without any significant matrix interferences. Liquid–liquid extraction with butyl acetate was applied for serum samples cleanup and preconcentration of studied designer benzodiazepines. The method was validated in terms of linearity, limit of detection, limit of quantification, matrix effects, specificity, precision, accuracy, recovery, and sample stability. The limit of detection values were 0.10–0.15 ng/mL. The method was applied to a spiked serum sample to demonstrate its applicability for systematic toxicology analysis. Furthermore, a capillary chromatographic method with micellar electrokinetic chromatography was used for the estimation of partition coefficients of studied designer benzodiazepines as important parameters to evaluate their pharmacological and toxicological properties.     

New cathinone‐derived designer drugs 3‐bromomethcathinone and 3‐fluoromethcathinone: studies on their metabolism in rat urine and human liver microsomes using GC–MS and LC–high‐resolution MS and their detectability in urine

3‐Bromomethcathinone (3‐BMC) and 3‐Fluoromethcathinone (3‐FMC) are two new designer drugs, which were seized in Israel during 2009 and had also appeared on the illicit drug market in Germany. These two compounds were sold via the Internet as so‐called “bath salts” or “plant feeders.” The aim of the present study was to identify for the first time the 3‐BMC and 3‐FMC Phase I and II metabolites in rat urine and human liver microsomes using GC–MS and LC–high‐resolution MS (HR‐MS) and to test for their detectability by established urine screening approaches using GC–MS or LC–MS. Furthermore, the human cytochrome‐P450 (CYP) isoenzymes responsible for the main metabolic steps were studied to highlight possible risks of consumption due to drug–drug interaction or genetic variations. For the first aim, rat urine samples were extracted after and without enzymatic cleavage of conjugates. The metabolites were separated and identified by GC–MS and by LC–HR‐MS. The main metabolic steps were N‐demethylation, reduction of the keto group to the corresponding alcohol, hydroxylation of the aromatic system and combinations of these steps. The elemental composition of the metabolites identified by GC–MS could be confirmed by LC–HR‐MS. Furthermore, corresponding Phase II metabolites were identified using the LC–HR‐MS approach. For both compounds, detection in rat urine was possible within the authors' systematic toxicological analysis using both GC–MS and LC–MSⁿ after a suspected recreational users dose. Following CYP enzyme kinetic studies, CYP2B6 was the most relevant enzyme for both the N‐demethylation of 3‐BMC and 3‐FMC after in vitro–in vivo extrapolation. Copyright © 2012 John Wiley & Sons, Ltd.     

Structural Elucidation of in vivo and in vitro Metabolites of Epiberberine in Rat and Its Liver and Intestines by Liquid Chromatography-Tandem Mass Spectrometry

The in vivo and in vitro metabolism of epiberberine was investigated using a highly specific and sensitive liquid chromatography–mass spectrometry (LC–MS/MS) method. In vivo samples including rat urine, feces, and plasma samples were collected individually after ingestion of 35 mg/kg epiberberine to healthy rats. In vitro samples were prepared by incubating epiberberine with homogenized liver and intestinal flora of rats, respectively. As a result, at least 17, 3 and 5 metabolites were found in rat urine, feces, and plasma, respectively. Additionally, 1 and 3 metabolites were found in the rat intestinal flora and homogenized liver incubation mixtures, respectively.     

Identification and structural characterization of in vivo metabolites of ketorolac using liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS)

In vivo metabolites of ketorolac (KTC) have been identified and characterized by using liquid chromatography positive ion electrospray ionization high resolution tandem mass spectrometry (LC/ESI‐HR‐MS/MS) in combination with online hydrogen/deuterium exchange (HDX) experiments. To identify in vivo metabolites, blood urine and feces samples were collected after oral administration of KTC to Sprague–Dawley rats. The samples were prepared using an optimized sample preparation approach involving protein precipitation and freeze liquid separation followed by solid‐phase extraction and then subjected to LC/HR‐MS/MS analysis. A total of 12 metabolites have been identified in urine samples including hydroxy and glucuronide metabolites, which are also observed in plasma samples. In feces, only O‐sulfate metabolite and unchanged KTC are observed. The structures of metabolites were elucidated using LC‐MS/MS and MSⁿ experiments combined with accurate mass measurements. Online HDX experiments have been used to support the structural characterization of drug metabolites. The main phase I metabolites of KTC are hydroxylated and decarbonylated metabolites, which undergo subsequent phase II glucuronidation pathways. Copyright © 2012 John Wiley & Sons, Ltd.     

Identification and structural characterization by LC‐ESI‐IONTRAP and LC‐ESI‐TOF of some metabolic conjugation products of homovanillic acid in urine of neuroblastoma patients

The levels of urinary catecholamine metabolites, such as homovanillic acid (HVA) and vanillylmandelic acid, are routinely used as a clinical tool in the diagnosis and follow‐up of neuroblastoma (NB) patients. Recently, in the Clinical Pathology Laboratory Unit of G. Gaslini Children Hospital, a commercial method that employs liquid chromatography coupled to electrochemical detection (LC‐EC) has been introduced for the measurement of these metabolites in the routine laboratory practice. Using this LC‐EC method, an unknown peak could be observed only in samples derived from NB patients. To investigate the nature of this peak, we used a combination of liquid chromatography‐time‐of‐flight mass spectrometry (LC‐TOF‐MS) and liquid chromatography‐ion trap tandem mass spectrometry (LC‐IT‐MS). The first approach was used to obtain the elemental composition of the ions present in this new signal. To get additional structural information useful for the elucidation of unknown compounds, the ion trap analyzer was exploited. We were able to identify not just one, but three unknown signals in urine samples from NB patients which corresponded to three conjugated products of HVA: HVA sulfate and two glucuronoconjugate isomers. The enzymatic hydrolysis with β‐glucuronidase confirmed the proposed structures, while the selective alkaline hydrolysis allowed us to distinguish the difference between phenol‐ and acyl‐glucuronide of HVA. The latter was the unknown peak observed in LC‐EC separations of urine samples from NB patients. Copyright © 2012 John Wiley & Sons, Ltd.     

Liquid chromatography coupled to quadruple time‐of‐flight tandem mass spectrometry for microcystin analysis in freshwaters: method performances and characterisation of a novel variant of microcystin‐RR

Cyanobacteria, also called blue‐green algae, occur worldwide within water blooms in eutrophic lakes and drinking water reservoirs, producing several biotoxins (cyanotoxins). Among these, microcystins (MCs) are a group of cyclic heptapeptides showing potent hepatotoxicity and activity as tumour promoters. So far, at least 89 MCs from different cyanobacteria genera have been characterised. Herein, ion trap, matrix‐assisted laser desorption/ionisation time‐of‐flight (MALDI‐ToF) and quadruple time‐of‐flight (Q‐ToF) mass spectrometry (MS)‐based methods were tested and compared for analysing MCs in freshwaters. Method performances in terms of limit of detection, limit of quantification, mean recoveries, repeatability, and specificity were evaluated. In particular, a liquid chromatography/electrospray ionisation (LC/ESI)‐Q‐ToF‐MS/MS method was firstly described to analyse MCs in freshwaters; this technique is highly selective and sensitive, and allowed us to characterise the molecular structure of an unknown compound. Indeed, the full structural characterisation of a novel microcystin variant from a bloom of Planktothrix rubescens in the Lake Averno, near Naples, was attained by the study of the fragmentation pattern. The new cyanotoxin was identified as the 9‐acetyl‐Adda variant of microcystin‐RR. Copyright © 2009 John Wiley & Sons, Ltd.     

Characterization and in vitro phase I microsomal metabolism of designer benzodiazepines — an update comprising adinazolam,cloniprazepam, fonazepam, 3‐hydroxyphenazepam,metizolam and nitrazolam

Designer benzodiazepines represent an emerging class of new psychoactive substances. While other classes of new psychoactive substances such as cannabinoid receptor agonists and designer stimulants are mainly consumed for hedonistic reasons, designer benzodiazepines may also be consumed as ‘self‐medication’ by persons suffering from anxiety or other psychiatric disorders or as stand‐by ‘antidote’ by users of stimulant and hallucinogenic drugs. In the present study, five benzodiazepines (adinazolam, cloniprazepam, fonazepam, 3‐hydroxyphenazepam and nitrazolam) and one thienodiazepine (metizolam) offered as ‘research chemicals’ on the Internet were characterized and their main in vitro phase I metabolites tentatively identified after incubation with pooled human liver microsomes. For all compounds, the structural formula declared by the vendor was confirmed by nuclear magnetic resonance spectroscopy, gas chromatography–mass spectrometry (MS), liquid chromatography MS/MS and liquid chromatography quadrupole time‐of‐flight MS analysis. The detected in vitro phase I metabolites of adinazolam were N‐desmethyladinazolam and N‐didesmethyladinazolam. Metizolam showed a similar metabolism to other thienodiazepines comprising monohydroxylations and dihydroxylation. Cloniprazepam was metabolized to numerous metabolites with the main metabolic steps being N‐dealkylation, hydroxylation and reduction of the nitro function. It has to be noted that clonazepam is a metabolite of cloniprazepam, which may lead to difficulties when interpreting analytical findings. Nitrazolam and fonazepam both underwent monohydroxylation and reduction of the nitro function. In the case of 3‐OH‐phenazepam, no in vitro phase I metabolites were detected. Formation of licensed benzodiazepines (clonazepam after uptake of cloniprazepam) and the sale of metabolites of prescribed benzodiazepines (fonazepam, identical to norflunitrazepam, and 3‐hydroxyphenazepam) present the risk of incorrect interpretation of analytical findings. Copyright © 2016 John Wiley & Sons, Ltd.     

Metabolite profiling of ginsenosides in rat plasma,urine and feces by LC–MS/MS and its application to a pharmacokinetic study after oral administration of Panax ginseng extract

Panax ginseng is widely consumed as a functional food in the form of tea, powder, capsules, among others, and possesses a range of pharmacological activities including adaptogenic, immune‐modulatory, anti‐tumor, anti‐aging and anti‐inflammatory effects. The aim of this study was to identify and quantify the major ginsenosides and their metabolites in rat plasma, urine and feces after administration of P. ginseng extract using LC–MS/MS. We collected rat plasma samples at 0.5, 1, 2, 4, 8, 12, 24 and 48 h, and the amounts of urine and fecal samples accumulated in 24 h. Fourteen major ginsenosides and their metabolites were observed in fecal samples at high levels; however, low levels of 11 ginsenosides were detected in urine samples. The pharmacokinetics of the major ginsenosides and their metabolites was investigated in plasma. The results indicated that the maximum plasma concentration, time to maximum concentration and area under the curve of compound K were significantly greater than those of other ginsenosides. This study thus provides valuable information for drug development and clinical application of P. ginseng.     

A fast and simple approach for the quantification of 40 illicit drugs,medicines, and pesticides in blood and urine samples by UHPLC‐MS/MS

A fast and simple approach to overcome challenges in emergency toxicological analysis, using ultra‐high performance liquid chromatography–tandem mass spectrometry (UHPLC‐MS/MS) has been developed, for the detection of analytes in blood and urine samples from the following drug classes: analgesics, benzodiazepines, antidepressants, anticonvulsants, drugs of abuse, and pesticides. These substances are relevant in the context of emergency toxicology in Brazil. The sample preparation procedure was relatively easy and fast to perform. The method was fully validated giving limits of in the range of 0.5 and 20 ng mL^?1 for blood and urine samples. The intraday and interday precision and accuracy were considered adequate for all analytes once the relative standard deviation (RSD) (%) was lower than 20% for quality control (QC) low and lower than 15% for CQ medium and high. The developed method was successfully applied to 320 real samples collected at the Poison Control Center of São Paulo, and 89.1% have shown to be positive for some of the analytes. This confirms its applicability and importance to emergency toxicological analysis, and it could be very useful in both fields of clinical and forensic toxicology.     

New designer drug 1-(3-trifluoromethylphenyl) piperazine (TFMPP): gas chromatography/mass spectrometry and liquid chromatography/mass spectrometry studies on its phase I and II metabolism and on its toxicological detection in rat urine

Studies are described on the phase I and II metabolism and the toxicological analysis of the piperazine-derived designer drug 1-(3-trifluoromethylphenyl)piperazine (TFMPP) in rat urine using gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS). The identified metabolites indicated that TFMPP was extensively metabolized, mainly by hydroxylation of the aromatic ring and by degradation of the piperazine moiety to N-(3-trifluoromethylphenyl)ethylenediamine, N-(hydroxy-3-trifluoromethylphenyl)ethylenediamine, 3-trifluoromethylaniline, and hydroxy-3-trifluoromethylaniline. Phase II reactions included glucuronidation, sulfatation and acetylation of phase I metabolites. The authors' systematic toxicological analysis (STA) procedure using full-scan GC/MS after acid hydrolysis, liquid-liquid extraction and microwave-assisted acetylation allowed the detection of TFMPP and its above-mentioned metabolites in rat urine after single administration of a dose calculated from the doses commonly taken by drug users. Assuming similar metabolism, the described STA procedure should be suitable for proof of an intake of TFMPP in human urine.     

In vitro and in vivo metabolism studies of dimethazine

The use of anabolic steroids is prohibited in sports. Effective control is done by monitoring their metabolites in urine samples collected from athletes. Ethical objections however restrict the use of designer steroids in human administration studies. To overcome these problems alternative in vitro and in vivo models were developed to identify metabolites and to assure a fast response by anti‐doping laboratories to evolutions on the steroid market. In this study human liver microsomes and an uPA^+/+‐SCID chimeric mouse model were used to elucidate the metabolism of a steroid product called ‘Xtreme DMZ’. This product contains the designer steroid dimethazine (DMZ), which consists of two methasterone molecules linked by an azine group. In the performed stability study, degradation from dimethazine to methasterone was observed. By a combination of LC‐High Resolution Mass Spectrometry (HRMS) and GC‐MS(/MS) analysis methasterone and six other dimethazine metabolites (M1–M6), which are all methasterone metabolites, could be detected besides the parent compound in both models. The phase II metabolism of dimethazine was also investigated in the mouse urine samples. Only metabolites M1 and M2 were exclusively detected in the glucuro‐conjugated fraction; all other compounds were also found in the free fraction. For effective control of DMZ misuse in doping control samples, screening for methasterone and methasterone metabolites should be sufficient. Copyright © 2016 John Wiley & Sons, Ltd.     

Rapid and simple determination of psychotropic phenylalkylamine derivatives in urine by direct injection liquid chromatography–electrospray ionization–tandem mass spectrometry

A direct injection liquid chromatography–electrospray ionization–tandem mass spectrometric method (LC‐ESI‐MS/MS) was developed and validated for the rapid and simple determination of 13 phenylalkylamine derivatives. Eight deuterium‐labeled compounds were prepared for use as internal standards (ISs) to quantify the analytes. Urine samples mixed with ISs were centrifuged, filtered through 0.22 µm filters and then injected directly into the LC‐ESI‐MS/MS system. The mobile phase was composed of 0.2% formic acid and 2 mM ammonium formate in distilled water and 0.2% formic acid and 2 mM ammonium formate in acetonitrile. The analytical column was a Capcell Pak MG‐II C₁₈ (150 × 2.0 mm i.d., 5 µm, Shiseido). Separation and detection of the analytes were accomplished within 10 min. The linear ranges were 5–750 ng/mL (ephedrine and fenfluramine), 10–750 ng/mL (3,4‐methylenedioxyamphetamine, phendimetrazine, methamphetamine, 3,4‐methylenedioxyethylamphetamine and benzphetamine), 20–750 ng/mL (norephedrine, amphetamine, phentermine and ketamine) and 30–1000 ng/mL (3,4‐methylenedioxymethamphetamine and norketamine), with determination coefficients, R², ≥ 0.9967. The intra‐day and inter‐day precisions were within 19.1%. The intra‐day and inter‐day accuracies ranged from ?16.0 to 18.7%. The lower limits of quantification for all the analytes were lower than 26.5 ng/mL. The applicability of the method was examined by analyzing urine samples from drug abusers (n = 30). Copyright © 2012 John Wiley & Sons, Ltd.     

Efficiency of a miniaturized silica monolithic cartridge in reducing matrix ions as demonstrated in the simultaneous extraction of morphine and codeine from urine samples for quantification with liquid chromatography-tandem mass spectrometry (LC-MS/MS)

Presence of matrix ions could negatively affect the sensitivity and selectivity of liquid chromatography‐tandem mass spectrometer (LC‐MS/MS). In this study, the efficiency of a miniaturized silica monolithic cartridge in reducing matrix ions was demonstrated in the simultaneous extraction of morphine and codeine from urine samples for quantification with LC‐MS. The miniaturized silica monolith with hydroxyl groups present on the largely exposed surface area function as a weak cation exchanger for solid phase extraction (SPE). The miniaturized silica cartridge in 1 cm diameter and 0.5 cm length was housed in a 2‐ml syringe fixed over a SPE vacuum manifold for extraction. The cleaning effectiveness of the cartridge was confirmed by osmometer, atomic absorption spectrometer, LC‐MS and GC‐TOFMS. The drugs were efficiently extracted from urine samples with recoveries ranging from 86% to 114%. The extracted analytes, after concentration and reconstitution, were quantified using LC‐MS/MS. The limits of detection for morphine and codeine were 2 ng/ml and 1 ng/mL, respectively. The relative standard deviations of measurements ranged from 3% to 12%. The monolithic sorbent offered good linearity with correlation coefficients > 0.99, over a concentration range of 50–500 ng/ml. The silica monolithic cartridge was found to be more robust than the particle‐based packed sorbent and also the commercial cartridge with regards to its recyclability and repeated usage with minimal loss in efficiency. Our study demonstrated the efficiency of the miniaturized silica monolith for removal of matrix ions and extraction of drugs of abuse in urinary screening. Copyright © 2011 John Wiley & Sons, Ltd.     

Quantitative determination of metformin,glyburide and its metabolites in plasma and urine of pregnant patients by LC‐MS/MS

This report describes the development and validation of an LC‐MS/MS method for the quantitative determination of glyburide (GLB), its five metabolites (M1, M2a, M2b, M3 and M4) and metformin (MET) in plasma and urine of pregnant patients under treatment with a combination of the two medications. The extraction recovery of the analytes from plasma samples was 87–99%, and that from urine samples was 85–95%. The differences in retention times among the analytes and the wide range of the concentrations of the medications and their metabolites in plasma and urine patient samples required the development of three LC methods. The lower limit of quantitation (LLOQ) of the analytes in plasma samples was as follows: GLB, 1.02 ng/mL; its five metabolites, 0.100–0.113 ng/mL; and MET, 4.95 ng/mL. The LLOQ in urine samples was 0.0594 ng/mL for GLB, 0.984–1.02 ng/mL for its five metabolites and 30.0 µg/mL for MET. The relative deviation of this method was <14% for intra‐day and inter‐day assays in plasma and urine samples, and the accuracy was 86–114% in plasma, and 94–105% in urine. The method described in this report was successfully utilized for determining the concentrations of the two medications in patient plasma and urine. Copyright © 2014 John Wiley & Sons, Ltd.     

Developing a robust LC–MS/MS method to quantify Zn‐DTPA,a zinc chelate in human plasma and urine

Quantitation of Zn‐DTPA (zinc diethylenetriamene pentaacetate, a metal chelate) in complex biological matrix is extremely challenging on account of its special physiochemical properties. This study aimed to develop a robust and specific liquid chromatography–tandem mass spectrometry (LC–MS/MS) method for determination of Zn‐DTPA in human plasma and urine. The purified samples were separated on Proteonavi (250 × 4.6 mm, 5 μm; Shiseido, Ginza, Tokyo, Japan) and a C₁₈ guard column. The mobile phase consisted of methanol–2 mm ammonium formate (pH 6.3)–ammonia solution (50:50:0.015, v/v/v), flow rate 0.45 mL/min. The linear concentration ranges of the calibration curves for Zn‐DTPA were 1–100 μg/mL in plasma and 10–2000 μg/mL in urine. The intra‐ and inter‐day precisions for quality control (QC) samples were from 1.8 to 14.6% for Zn‐DTPA and the accuracies for QC samples were from −4.8 to 8.2%. This method was fully validated and successfully applied to the quantitation of Zn‐DTPA in plasma and urine samples of a healthy male volunteer after intravenous infusion administration of Zn‐DTPA. The result showed that the concentration of Zn‐DTPA in urine was about 20 times that in plasma, and Zn‐DTPA was completely (94.7%) excreted through urine in human.     

Analytical validation and clinical application of urinary vanillylmandelic acid and homovanillic acid by LC–MS/MS for diagnosis of neuroblastoma

Vanillylmandelic acid (VMA) and homovanillic acid (HVA) are clinical biomarkers for diagnosis of neuroblastoma (NB), which commonly occurs in the childhood. Development and application of a robust LC–MS/MS method for fast determination of these biomarkers for optimal laboratory testing of NB is essential in clinical laboratories. In present study, we developed and validated a simple liquid chromatography tandem mass spectrometry (LC–MS/MS) method for quick clinical testing of VMA and HVA for diagnosis of NB. The method was validated according to the current CLSI C62‐A and FDA guidelines. The age‐adjusted pediatric reference intervals and diagnostic performance were evaluated in both 24 h urine and random urine. Injection‐to‐injection time was 3.5 min. Inter‐ and intra‐assay coefficients of variation (CVs) were ≤3.88%. The lower limit of quantification and the limit of detection were 0.50 and 0.25 μmol/L for both VMA and HVA. Recoveries of VMA and HVA were in the ranges of 85–109% and 86–100% with CVs ≤5.76%. This method was free from significant matrix effect, carryover and interference. The establishment of age‐adjusted pediatric reference intervals by this LC–MS/MS method was favorable for the improvement in diagnostic performance, which was crucial for correct interpretation of test results from children in both 24 h and random urine.     

Doping control analysis of desmopressin in human urine by LC‐ESI‐MS/MS after urine delipidation

The World Anti‐Doping Agency (WADA) has recently added desmopressin, a synthetic analogue of the endogenous peptide hormone arginine vasopressin, to the Prohibited List, owing to the potential masking effects of this drug on hematic parameters useful to detect blood doping. A qualitative method for detection of desmopressin in human urine by high‐performance liquid chromatography–electrospray tandem mass spectrometry (LC‐ESI‐MS/MS) has been developed and validated. Desmopressin purification from urine was achieved by means of delipidation with a 60:40 di‐isopropyl ether/n‐butanol and solid‐phase extraction with WCX cartridges. The lower limit of detection was 25 pg/mL. Extraction recovery was determined as 59.3% (SD 29.4), and signal reduction owing to ion suppression was estimated to be 42.7% (SD 12.9). The applicability of the method was proven by the analysis of real urine samples obtained after intravenous, oral and intranasal administration of desmopressin, achieving unambiguous detection of the peptide in all the cases. Copyright © 2012 John Wiley & Sons, Ltd.     

Metabolic profile of glyburide in human liver microsomes using LC‐DAD‐Q‐TRAP‐MS/MS

The sulfonylurea urea drug glyburide (glibenclamide) is widely used for the treatment of diabetes milletus and gestational diabetes. In previous studies monohydroxylated metabolites were identified and characterized for glyburide in different species, but the metabolite owing to the loss of cyclohexyl ring was identified only in mouse. Glyburide upon incubation with hepatic microsomes resulted in 10 metabolites for human. The current study identifies new metabolites of glyburide along with the hydroxylated metabolites that were reported earlier. The newly identified drug metabolites are dihydroxylated metabolites, a metabolite owing to the loss of cyclohexyl ring and one owing to hydroxylation with dehydrogenation. Among the 10 identified metabolites, there were six monohydroxylated metabolites, one dihydroxylated metabolite, two metabolites owing to hydroxylation and dehydrogenation, and one metabolite owing to the loss of cyclohexyl ring. New metabolites of glyburide were identified and characterized using liquid chromatography–diode array detector–quadruple‐ion trap–mass spectrometry/mass spectrometry (LC‐DAD‐Q‐TRAP‐MS/MS). An enhanced mass scan–enhanced product ion scan with information‐dependent acquisition mode in a Q‐TRAP‐MS/MS system was used to characterize the metabolites. Liquid chromatography with diode array detection was used as a complimentary technique to confirm and identify the metabolites. Metabolites formed in higher amounts were detected in both diode array detection and mass spectrometry detection. Copyright © 2012 John Wiley & Sons, Ltd.     

Urinary metabolomics analysis reveals the effect of volatile oil from Angelica sinensis on LPS‐induced inflammation rats

Lipopolysaccharide (LPS)‐induced inflammation occurs commonly and volatile oil from Angelica sinensis (VOAS) can be used as an anti‐inflammatory agent. The molecular mechanisms that allow the anti‐inflammatory factors to be expressed are still unknown. In this paper, we applied gas chromatography–mass spectrometry (GC–MS) and high‐performance liquid chromatography–time‐of‐flight mass spectrometry (LC‐Q/TOF–MS) based on a metabolomics platform coupled with a network approach to analyze urine samples in three groups of rats: one with LPS‐induced inflammation (MI); one with intervention with VOAS; and normal controls (NC). Our study found definite metabolic footprints of inflammation and showed that all three groups of rats, MI, intervention with VOAS and NC have distinct metabolic profiles in urine. The concentrations of 48 metabolites differed significantly among the three groups. The metabolites in urine were screened by the GC–MS and LC‐Q/TOF–MS methods. The significantly changed metabolites (p < 0.05, variable importance in projection > 1.5) between MI, NC and VOAS were included in the metabolic networks. Finally, hub metabolites were screened, including glycine, arachidonic acid, l ‐glutamate, pyruvate and succinate, which have high values of degree (k). the Results suggest that disorders of glycine, arachidonic acid, l ‐glutamate, pyruvate and succinate metabolism might play an important part in the predisposition and development of LPS‐induced inflammation. By applying metabolomics with network methods, the mechanisms of diseases are clearly elucidated.     

A quantitative LC–MS/MS method for determination of a small molecule agonist of EphA2 in mouse plasma and brain tissue

Compound 27 {1, 12‐bis[4‐(4‐amino‐6,7‐dimethoxyquinazolin‐2‐yl)piperazin‐1‐yl]dodecane‐1,12‐dione} is a novel small molecule agonist of EphA2 receptor tyrosine kinase. It showed much improved activity for the activation of EphA2 receptor compared with the parental compound doxazosin. To support further pharmacological and toxicological studies of the compound, a method using liquid chromatography and electrospray ionization tandem mass spectrometry (LC–MS/MS) has been developed for the quantification of this compound. Liquid–liquid extraction was used to extract the compound from mouse plasma and brain tissue homogenate. Reverse‐phase chromatography with gradient elution was performed to separate compound 27 from the endogenous molecules in the matrix, followed by MS detection using positive ion multiple reaction monitoring mode. Multiple reaction monitoring transitions m/z 387.3 → 290.1 and m/z 384.1 → 247.1 were selected for monitoring compound 27 and internal standard prazosin, respectively. The linear calibration range was 2–200 ng/mL with the intra‐ and inter‐day precision and accuracy within the acceptable range. This method was successfully applied to the quantitative analysis of compound 27 in mouse plasma and brain tissue with different drug administration routes.