P450‐catalyzed vs. electrochemical oxidation of haloperidol studied by ultra‐performance liquid chromatography/electrospray ionization mass spectrometry

The metabolites formed via the major metabolic pathways of haloperidol in liver microsomes, N‐dealkylation and ring oxidation to the pyridinium species, were produced by electrochemical oxidation and characterized by ultra‐performance liquid chromatography/electrospray ionization mass spectrometry (UPLC/ESI‐MS). Liver microsomal incubations and electrochemical oxidation in the presence of potassium cyanide (KCN) resulted in two diastereomeric cyano adducts, proposed to be generated from trapping of the endocyclic iminium species of haloperidol. Electrochemical oxidation of haloperidol in the presence of KCN gave a third isomeric cyano adduct, resulting from trapping of the exocyclic iminium species of haloperidol. In the electrochemical experiments, addition of KCN almost completely blocked the formation of the major oxidation products, namely the N‐dealkylated products, the pyridinium species and a putative lactam. This major shift in product formation by electrochemical oxidation was not observed for the liver microsomal incubations where the N‐dealkylation and the pyridinium species were the major metabolites also in the presence of KCN. The previously not observed dihydropyridinium species of haloperidol was detected in the samples, both from electrochemical oxidation and the liver microsomal incubations, in the presence of KCN. The presence of the dihydropyridinium species and the absence of the corresponding cyano adduct lead to the speculation that an unstable cyano adduct was formed, but that cyanide was eliminated to regenerate the stable conjugated system. The formation of the exocyclic cyano adduct in the electrochemical experiments but not in the liver microsomal incubations suggests that the exocyclic iminium intermediate, obligatory in the electrochemically mediated N‐dealkylation, may not be formed in the P450‐catalyzed reaction. Copyright © 2010 John Wiley & Sons, Ltd.     

Rapid detection and characterization of reactive drug metabolites in vitro using several isotope‐labeled trapping agents and ultra‐performance liquid chromatography/time‐of‐flight mass spectrometry

Reactive metabolites are believed to be one of the main reasons for unexpected drug‐induced toxicity issues, by forming covalent adducts with cell proteins or DNA. Due to their high reactivity and short lifespan they are not directly detected by traditional analytical methods, but are most traditionally analyzed by liquid chromatography/tandem mass spectrometry (LC/MS/MS) after chemical trapping with nucleophilic agents such as glutathione. Here, a simple but very efficient assay was built up for screening reactive drug metabolites, utilizing stable isotope labeled glutathione, potassium cyanide and semicarbazide as trapping agents and highly sensitive ultra‐performance liquid chromatography/time‐of‐flight mass spectrometry (UPLC/TOFMS) as an analytical tool. A group of twelve structurally different compounds was used as a test set, and a large number of trapped metabolites were detected for most of them, including many conjugates not reported previously. Glutathione‐trapped metabolites were detected for nine of the twelve test compounds, whereas cyanide‐trapped metabolites were found for eight and semicarbazide‐trapped for three test compounds. The high mass accuracy of TOFMS provided unambiguous identification of change in molecular formula by formation of a reactive metabolite. In addition, use of a mass defect filter was found to be a usable tool when mining the trapped conjugates from the acquired data. The approach was shown to provide superior detection sensitivity in comparison to traditional methods based on neutral loss or precursor ion scanning with a triple quadrupole mass spectrometer, and clearly more efficient detection and characterization of reactive drug metabolites with a simpler test setup. Copyright © 2009 John Wiley & Sons, Ltd.     

Identification and quantification of glutathione adducts of clozapine using ultra-high-performance liquid chromatography with orthogonal acceleration time-of-flight mass spectrometry and inductively coupled plasma mass spectrometry

The application of sulphur-specific detection via ultra-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (UPLC/ICPMS) to detect and quantify the glutathione (GSH)-adducts produced via the in vitro formation of reactive metabolites is demonstrated. The adducts were formed in human liver microsomes supplemented with unlabelled GSH for clozapine. The calculation of adduct concentration was performed via comparison of the peak areas to calibration curves constructed from omeprazole, a sulphur-containing compound over the range of 0.156 to 15.62 μM of sulphur with a detection limit of 1.02 ng of sulphur on-column. Identification of the adducts was performed using conventional UPLC/time-of-flight (TOF)-MS with the calculation of clozapine intrinsic clearance carried out by high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). The use of ICPMS in this way appears to offer a novel, rapid and sensitive means of determining the quantity of GSH conjugates with the combined adducts producing 0.9 μM of reactive metabolite out of a total of 3.5 μM of metabolites. The GSH adduct therefore represents 26% of this total produced as a result of the metabolism of drug to reactive species.     

Simultaneous quantification of vortioxetine,fluoxetine and their metabolites in rat plasma by UPLC–MS/MS

In this study, a specific and quick ultra-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) method was fully developed and validated for simultaneous measurement of the rat plasma levels of vortioxetine (VOR), Lu AA34443 (the major metabolite of VOR), fluoxetine and its metabolite norfluoxetine with diazepam as the internal standard (IS). After a simple protein precipitation with acetonitrile for sample preparation, the separation of the analytes were performed on an Acquity UPLC BEH C18 (2.1 × 50 mm, 1.7 μm) column, with acetonitrile and 0.1% formic acid in water as mobile phase by gradient elution. The detection was achieved on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring mode via an electrospray ionization source. Good linearity was observed in the calibration curve for each analyte. The data of precision, accuracy, matrix effect, recovery and stability all conformed to the bioanalytical method validation of acceptance criteria of US Food and Drug Administration recommendations. The newly developed UPLC–MS/MS method allowed simultaneous quantification of VOR, fluoxetine and their metabolites for the first time and was successfully applied to a pharmacokinetic study in rats.     

Analyses of macrolide antibiotic residues in eggs, raw milk, and honey using both ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry and high-performance liquid chromatography/tandem mass spectrometry

Two liquid chromatography mass spectrometric techniques, i.e. ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-Tof MS) and high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS), were used for quantification, confirmation or identification of six macrolide antibiotic residues and/or their degradation products in eggs, raw milk, and/or honey. Macrolides were extracted from food samples by acetonitrile or phosphate buffer (0.1 M, pH 8.0), and sample extracts were further cleaned up using solid-phase extraction cartridges. UPLC/Q-Tof data were acquired in Tof MS full scan mode that allowed both quantification and confirmation of macrolides, and identification of their degradation products. LC/MS/MS data acquisition was achieved using multiple reaction monitoring (MRM), i.e. two transitions, to provide a high degree of sensitivity and repeatability. Matrix-matched standard calibration curves with the use of roxithromycin as an internal standard were utilized to achieve the best accuracy of the method. Both techniques demonstrated good quantitative performance in terms of accuracy and repeatability. LC/MS/MS had advantages over UPLC/Q-Tof MS in that its limits of detection were lower and repeatability was somewhat better. UPLC/Q-Tof provided ultimate and unequivocal confirmation of positive findings, and allowed degradation product identification based on accurate mass. The combination of the two techniques can be very beneficial or complementary in routine analysis of macrolide antibiotic residues and their degradation products in food matrices to ensure the safety of food supply.     

A high-throughput liquid chromatography/tandem mass spectrometry method for screening glutathione conjugates using exact mass neutral loss acquisition

Chemically reactive metabolites may cause hepatotoxicity and as a result liver failure or other adverse side reactions. Therefore, this is a vital topic of interest because early reactive metabolite screening may prevent compound failure at a later stage. In order to address this issue, a screening assay has been developed to detect the formation of reactive metabolites by using glutathione as a trapping reagent, which will allow us to search for phase I metabolites and also glutathiones during in vitro metabolite screening using liquid chromatography/tandem mass spectrometry (LC/MS/MS) with exact mass. Glutathione conjugations when fragmented by the mass spectrometer give a common loss corresponding to the pyroglutamic acid moiety, which can be monitored. Until recently, this work has been carried out with triple quadrupole technology using nominal mass. The advantage of the hybrid quadrupole time-of-flight mass spectrometer is the selectivity and sensitivity that can be achieved. Exact neutral loss detection is achieved via sequential low- and high-energy MS acquisitions. After detection of the loss of the pyroglutamic acid moiety, using a window of +/-20 mDa on the high-energy scan, MS/MS is carried out on the parent mass of interest to confirm the common neutral loss.     

Lysophosphatidylcholine Biomarkers of Lung Cancer Detected by Ultra-performance Liquid Chromatography Coupled with Quadrupole Time-of-flight Mass Spectrometry

Centrifugal ultrafiltration after methanol extraction of whole plasma was used as an optimal condition for the preparation of blood plasma before metabonomic studies. The plasma samples from 102 lung cancer patients and 34 healthy volunteers were prepared with this approach. With ultra-performance liquid chromatography(UPLC) coupled with quadrupole time-of-flight mass spectrometry(Q-TOF MS) analysis, the samples were investigated in order to find potential disease biomarkers. After data acquisition, orthogonal signal correction partial least squares models were built to differentiate the healthy volunteers from lung cancer patients and to identify metabolites that showed significantly different expression between the two groups. Several metabolite ions were identified as potential biomarkers according to the variable importance in the project(VIP) value in both ion modes. Five lysophosphatidylcholines were further identified as specifically lysoPC 16:0, isomer of lysoPC 16:0, lysoPC 18:0, lysoPC 18:1 and lysoPC 18:2. These results suggest that UPLC coupled with Q-TOF MS is an effective technique for the analysis of plasma metabolites in metabonomic studies.     

乳制品中那他霉素的超高效液相色谱-串联质谱法快速测定

建立了超高效液相色谱-电喷雾串联质谱(UPLC-MS/MS)快速检测乳制品中那他霉素的方法。样品用甲醇提取,以甲醇-水为流动相经反相色谱柱分离后,采用多反应监测(MRM)负离子模式检测,定性离子对为m/z663.6/421.1和m/z663.6/439.1,其中m/z663.6/421.1用于外标法定量。空白样品及其加标实验结果表明:特征离子相对强度比值稳定,无基质干扰,结合保留时间可实现准确的定性定量;方法定量下限为50.0μg/kg;乳制品加标量为50~500μg/kg时,平均回收率为80%~91%,相对标准偏差(n=6)为2.7%~5.2%。方法简单、灵敏、稳定,可满足乳制品中那他霉素的快速检测与确证需要。     

A ferrocene-based reagent for the conjugation and quantification of reactive metabolites

In the present study, a method for the analysis of reactive metabolites via liquid chromatography (LC) with inductively coupled plasma–mass spectrometry (MS) was developed. A ferrocenyl-modified glutathione (GSH) reagent, consisting of GSH and succinimidyl-3-ferrocenylpropionate, was synthesized. Derivatization of the tripeptide was performed at the N-terminus, leaving the nucleophilic thiol group vacant for the attack of electrophilic compounds. The potential of ferrocenylpropionate (FP)-GSH as a trapping agent for reactive metabolites was investigated using an electrochemical flow-through cell for metabolism simulation coupled online to a LC system with electrospray ionization mass spectrometric detection. The pharmaceuticals amodiaquine, an antimalarial agent, and clozapine, an antipsychotic compound, served as model substances. By proving the successful adduct formation between the reactive metabolite and ferrocene-labeled GSH, it could be shown that FP-GSH is an effective trapping agent which eases routine reversed-phase LC analyses. In contrast to GSH, which is usually used for the conjugation of reactive metabolites and where the resulting adducts often show no or only very little retention, FP-GSH facilitates the detection of the corresponding metabolite adducts due to higher retention times.     

Detection and characterization of olmutinib reactive metabolites by LC–MS/MS: Elucidation of bioactivation pathways

Olmutinib (Olita?) is an orally bioavailable third generation epidermal growth factor receptor tyrosine kinase inhibitor. Olmutinib was approved in South Korea in May 2016 for the treatment of patients suffering from locally advanced or metastatic epidermal growth factor receptor T790M mutation‐positive non‐small cell lung cancer. Reactive olmutinib intermediates may be responsible for the severe side effects associated with the treatment. However, literature review revealed no previous reports on the structural identification of reactive olmutinib metabolites. In this work, the formation of reactive olmutinib metabolites in rat liver microsomes was investigated. Methoxylamine, glutathione, and potassium cyanide were used as capturing agents for aldehyde, iminoquinones, and iminium intermediates, respectively. The stable complexes formed were identified using liquid chromatography–tandem mass spectrometry. The major phase I metabolic pathway observed in vitro was hydroxylation of the piperazine ring. Seven potential reactive intermediates were characterized, including three iminium ions, three iminoquinones, and one aldehyde. Based on the findings, various bioactivation pathways were postulated. Hence, identifying the reactive intermediates of olmutinib that may be the cause of severe side effects can provide new insights, leading to improved treatments for patients.     

Improved detection of reactive metabolites with a bromine‐containing glutathione analog using mass defect and isotope pattern matching

Drug bioactivation leading to the formation of reactive species capable of covalent binding to proteins represents an important cause of drug‐induced toxicity. Reactive metabolite detection using in vitro microsomal incubations is a crucial step in assessing potential toxicity of pharmaceutical compounds. The most common method for screening the formation of these unstable, electrophilic species is by trapping them with glutathione (GSH) followed by liquid chromatography/mass spectrometry (LC/MS) analysis. The present work describes the use of a brominated analog of glutathione, N‐(2‐bromocarbobenzyloxy)‐GSH (GSH‐Br), for the in vitro screening of reactive metabolites by LC/MS. This novel trapping agent was tested with four drug compounds known to form reactive metabolites, acetaminophen, fipexide, trimethoprim and clozapine. In vitro rat microsomal incubations were performed with GSH and GSH‐Br for each drug with subsequent analysis by liquid chromatography/high‐resolution mass spectrometry on an electrospray time‐of‐flight (ESI‐TOF) instrument. A generic LC/MS method was used for data acquisition, followed by drug‐specific processing of accurate mass data based on mass defect filtering and isotope pattern matching. GSH and GSH‐Br incubations were compared to control samples using differential analysis (Mass Profiler) software to identify adducts formed via the formation of reactive metabolites. In all four cases, GSH‐Br yielded improved results, with a decreased false positive rate, increased sensitivity and new adducts being identified in contrast to GSH alone. The combination of using this novel trapping agent with powerful processing routines for filtering accurate mass data and differential analysis represents a very reliable method for the identification of reactive metabolites formed in microsomal incubations. Copyright © 2010 John Wiley & Sons, Ltd.     

High-resolution chromatography/time-of-flight MSE with in silico data mining is an information-rich approach to reactive metabolite screening

Electrophilic reactive metabolite screening by liquid chromatography/mass spectrometry (LC/MS) is commonly performed during drug discovery and early-stage drug development. Accurate mass spectrometry has excellent utility in this application, but sophisticated data processing strategies are essential to extract useful information. Herein, a unified approach to glutathione (GSH) trapped reactive metabolite screening with high-resolution LC/TOF MS(E) analysis and drug-conjugate-specific in silico data processing was applied to rapid analysis of test compounds without the need for stable- or radio-isotope-labeled trapping agents. Accurate mass defect filtering (MDF) with a C-heteroatom dealkylation algorithm dynamic with mass range was compared to linear MDF and shown to minimize false positive results. MS(E) data-filtering, time-alignment and data mining post-acquisition enabled detection of 53 GSH conjugates overall formed from 5 drugs. Automated comparison of sample and control data in conjunction with the mass defect filter enabled detection of several conjugates that were not evident with mass defect filtering alone. High- and low-energy MS(E) data were time-aligned to generate in silico product ion spectra which were successfully applied to structural elucidation of detected GSH conjugates. Pseudo neutral loss and precursor ion chromatograms derived post-acquisition demonstrated 50.9% potential coverage, at best, of the detected conjugates by any individual precursor or neutral loss scan type. In contrast with commonly applied neutral loss and precursor-based techniques, the unified method has the advantage of applicability across different classes of GSH conjugates. The unified method was also successfully applied to cyanide trapping analysis and has potential for application to alternate trapping agents.     

UPLC-Q-TOF/MS for Analysis of the Metabolites of Flavone Glycosides from Scutellaria baicalensis Georgi by Human Fecal Flora in Vitro

The active ingredients of Scutellaria baicalensis Georgi, a valuable traditional Chinese medicine, are polyhydroxyflavones, namely baicalin, scutellarin and wogonoside. However, information about the metabolic routes, metabolites and even more the effect of chemical structure on the stability of the three has been limited. In this article, the three natural compounds were incubated with human fecal flora, respectively, and highly sensitive and specific ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry implementing the MetaboLynx? software method was used for the drug metabolism study. The chromatographic separation was performed on a 1.7-μm particle size Syncronis C₁₈ column using a gradient elution system. The components in the extract were identified and confirmed according to the mass spectrometric fragmentation mechanisms, MS/MS fragment ions and relevant literature by means of electrospray ionization mass spectrometry in negative ion mode. With this method, a total of ten metabolites were identified based on MS and MS/MS data. The results indicated that hydrogenation, methylation and deglycosylation were the major metabolic pathways of the three flavone glycosides in vitro, and the metabolic stability was closely related to the chemical structure. This study will be helpful for fully understanding the impact of intestinal bacteria on these active components. Furthermore, this work demonstrated the potential of the ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry approach with MetaboLynx for quite rapid, simple, reliable and automated identification of metabolites of natural products.     

Investigating the in vitro metabolism of fipexide: characterization of reactive metabolites using liquid chromatography/mass spectrometry

The in vitro metabolism of the nootropic drug fipexide was studied using different liquid chromatography/mass spectrometry (LC/MS) techniques. This drug has been withdrawn from the market due to toxic effects. No previous reports have investigated the possible involvement of reactive metabolites in the toxicity of fipexide. The hydrolysis of this drug leads to the formation of two potentially toxic species, 3,4-methylenedioxybenzylpiperazine (MDBP) and 4-chlorophenoxyacetic acid (4-CPA). Here, we investigate the in vitro metabolism of fipexide in human, rat, mouse and dog, as well as of MDBP and 4-CPA in human and rat, while focusing on the formation of reactive metabolites. A combination of LC/MS analyses on a hybrid quadrupole-linear ion trap instrument and accurate mass data from QqTOF measurements was employed for the characterization of these metabolites. Microsomal metabolites of fipexide were MDBP, 4-CPA, fipexide N-oxide or hydroxyl, demethylenated fipexide and other minor ones, all of which were investigated by tandem mass spectrometry. Reactive metabolites were detected using several trapping procedures with small molecules such as glutathione, its ethyl ester derivative and N-acetylcysteine. The demethylenated metabolite, a catechol, formed its corresponding ortho-quinone, which readily reacts with these nucleophiles. MDBP was studied in a similar manner, due to its ability to form an analogous catechol. Because of its acidic nature, 4-CPA was assessed for possible acylglucuronide and acyl-CoA thioester metabolites, which could also be involved in bioactivation pathways. Several important metabolites were identified as potential mediators of toxicity via protein binding.     

Use of ultra-performance liquid chromatography/time-of-flight mass spectrometry with nozzle-skimmer fragmentation for comprehensive quantitative analysis of secondary metabolites in Arabidopsis thaliana

This study sought to develop techniques for LC/MS-based metabolomics and to verify that an MS/MS spectral tag (MS2T) could be used in practical secondary metabolite profiling. The retention time (RT), precursor ions, and fragment ions generated by nozzle-skimmer fragmentation were determined using ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC/TOF-MS) and compared with the MS2T. A standard mix was analyzed with UPLC/TOF-MS under the same conditions as were used to construct the MS2T. The difference in RT for the standards was less than 0.15 min and the average RSD was about 2.8%, suggesting that the analysis was highly repeatable. Both precursor ions and fragment ions were observed when the cone voltage was 75 V. Experimental data and fragmentation pattern in the MS2T annotation list were highly similar. Wild-type and cas-1 mutant Arabidopsis thaliana samples treated with an elicitor were analyzed using UPLC/TOF-MS. Sixty-five peaks were successfully annotated. Fragment ions were observed with nozzle-skimmer fragmentation in 50 of 65 (77%) peaks. The reliability of annotation may have increased as a result of fragment ions. Results of multivariate analysis suggested that cas-1 was related to induction of the biosynthesis of these flavonoids. The devised method facilitated practical secondary metabolite profiling.     

UPLC-Q-TOF/MS for Analysis of the Metabolites of Flavone Glycosides from Scutellaria baicalensis Georgi by Human Fecal Flora in Vitro

The active ingredients of Scutellaria baicalensis Georgi, a valuable traditional Chinese medicine, are polyhydroxyflavones, namely baicalin, scutellarin and wogonoside. However, information about the metabolic routes, metabolites and even more the effect of chemical structure on the stability of the three has been limited. In this article, the three natural compounds were incubated with human fecal flora, respectively, and highly sensitive and specific ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry implementing the MetaboLynx™ software method was used for the drug metabolism study. The chromatographic separation was performed on a 1.7-μm particle size Syncronis C₁₈ column using a gradient elution system. The components in the extract were identified and confirmed according to the mass spectrometric fragmentation mechanisms, MS/MS fragment ions and relevant literature by means of electrospray ionization mass spectrometry in negative ion mode. With this method, a total of ten metabolites were identified based on MS and MS/MS data. The results indicated that hydrogenation, methylation and deglycosylation were the major metabolic pathways of the three flavone glycosides in vitro, and the metabolic stability was closely related to the chemical structure. This study will be helpful for fully understanding the impact of intestinal bacteria on these active components. Furthermore, this work demonstrated the potential of the ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry approach with MetaboLynx for quite rapid, simple, reliable and automated identification of metabolites of natural products.

     

超高效液相色谱-四极杆-飞行时间质谱检测和鉴定猪尿中氯丙那林的主要代谢产物

采用超高效液相色谱-四极杆-飞行时间质谱(UPLC/Q-TOF MS)检测和鉴定了猪尿中氯丙那林的主要代谢产物,并讨论了氯丙那林在猪体内的主要代谢途径。按10 mg/kg(b. w.)的剂量口服灌食氯丙那林,分别采集给药前及给药后的猪尿液样品。采用UPLC/Q-TOF MS对样品进行分析,并应用质量亏损过滤和离子色谱峰提取等数据处理技术,在给药后24 h内的猪尿中检测和鉴定了9种氯丙那林的代谢产物,其中,Ⅰ相代谢产物2种,Ⅱ相代谢产物7种。然后,根据氯丙那林原形和代谢产物的碎片离子特征,对代谢产物的结构进行鉴定。最后,根据所鉴定的代谢产物,推测氯丙那林在猪体内的代谢途径包括苯环羟基化、β -羟基和仲氨基的葡萄糖醛酸轭合、羟基化后的葡萄糖醛酸和硫酸轭合等。研究结果表明,羟基化氯丙那林及其轭合产物的相对含量大于60%,明显高于氯丙那林原形及其轭合产物,是尿液中的主要代谢产物。本研究将为确定氯丙那林在动物体内的残留标示物及加强对氯丙那林非法使用的监控提供科学依据。     

Metabolite identification of a new antitumor agent icotinib in rats using liquid chromatography/tandem mass spectrometry

Icotinib, 4-[(3-ethynylphenyl)amino]-6,7-benzo-12-crown-4-quinazoline, is a new antitumor agent. The metabolic pathway of icotinib in rats was studied using liquid chromatography/tandem mass spectrometry (LC/MS(n)) analysis. Full scan and selected ion monitoring modes were used to profile the possible metabolites of icotinib in rat urine, feces and bile samples. Four phase I metabolites (M1-M4) and two phase II metabolites (M5, M6) were detected and characterized. Multiple-stage mass spectrometry and nuclear magnetic resonance (NMR) spectrometry were employed to elucidate structures of metabolites. Icotinib was metabolized to open the crown ether ring to form the main phase I metabolites. During metabolism, a reactive metabolite was formed. Using semicarbazide as a trapping agent, an intermediate arising from opening of the crown ether ring was detected as an aldehyde product by LC/MS/MS. These data indicated that ring opening of the crown ether was triggered by hydroxylation at the 8'-position of the ring to form a hemiacetal intermediate, which was further oxidized or reduced. Finally, the metabolic pathway of icotinib in rats was proposed.     

Ultra-performance liquid chromatography/time-of-flight mass spectrometry based metabolomics of raw and steamed Panax notoginseng

At present, metabolite profiling is of growing importance in herbal medicine fields such as breeding, formulation, quality control and clinical trials. This preliminary study indicated that ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC/TOFMS)-based metabolomics allows direct detection of down-stream derivatives of metabolites, arising from the herbal formulation process. This analytical approach allows the discrimination and tentative authentication of unique biomarkers related to different herbal extracts using unsupervised multivariate principal component analysis (PCA). The tentative identification of biomarkers is complemented significantly by the accurate mass measurement of TOFMS and the high resolution and high retention time reproducibility rendered by UPLC. The application of this approach in herbal extract discrimination and ginsenoside biomarker discovery of raw and steamed Panax notoginseng (Burk.) F.H. Chen is demonstrated and discussed.     

Ultra-performance liquid chromatography coupled to mass spectrometry as a sensitive and powerful technology for metabolomic studies

Metabolomics is the comprehensive assessment of endogenous metabolites of a biological system. These large-scale analyses of metabolites are intimately bound to advancements in ultra-performance liquid chromatography-electrospray (UPLC) technologies and have emerged in parallel with the development of novel mass analyzers and hyphenated techniques. Recently, the combination of UPLC with MS covers a number of polar metabolites, thus enlarging the number of detected analytes in the widely used separation sciences. This technology has rapidly been accepted by the analytical community and is being gradually applied to various fields such as metabolomics and traditional Chinese medicine (TCM). Given the power of the technology, metabolomics has become increasingly popular in drug development, molecular medicine, traditional medicine and other biotechnology fields, since it profiles directly the phenotype and changes thereof in contrast to other "-omics" technologies. Hyphenated UPLC/MS technique is becoming a useful tool in the study of body fluids, represents a promising hyphenated microseparation platform in metabolomics and has a strong potential to contribute to disease diagnosis. This review describes the applications of UPLC/MS in metabolomic research, and comparison role of HPLC/MS, NMR and GC/MS, highlights its advantages and limitations with certain characteristic examples in the life and TCM sciences.