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Tryptophan metabolism plays a crucial role in mediating gastrointestinal function. Here, in order to absolutely quantify tryptophan and its metabolites, a liquid chromatography-mass spectrometry (LC-MS) based targeted metabolomics approach was developed using N-dimethyl-/N-diethyl-amino naphthalene-1-sulfonyl chloride (Dns/Dens-Cl) as twins labeling (TL) reagents. Dns-Cl is famous in amine and phenol derivations, and structure is similar with Dens-Cl. The introduction of easily protonated moiety of tertiary ammonium-containing part in the derivatives from Dns to tryptophan and its metabolites not only improved the LC separation but also enhanced their MS response. In addition, the Dens labeled standards were used as internal standards to compensate for matrix effects and ensure accurate quantifications. With the proposed method, twelve metabolites in tryptophan pathway could be detected at sub-ng/mL levels using only 20μL rat serum (the limit of detection could reach 3pg/mL for tryptamine, N-acetyl-serotonin and 6-hydroxymelatonin). The sensitivity was enhanced about 1-2 orders of magnitude compared with non-derivatization method. Focusing on tryptophan pathway, the method was successfully applied to determine the absolute serum concentrations of twelve tryptophan metabolites in a vincristine-induced ileus rat model. A significant down-regulation of the tryptophan metabolism along the kynurenine pathway and up-regulation of serotonin pathway were uncovered. Our findings provide a deeper insight into the mechanism of gastrointestinal dysfunction., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Branched-chain amino acids (BCAAs) and branched-chain α-keto acids (BCKAs) play significant biological roles as they are involved in protein and neurotransmitter synthesis as well as energy metabolism pathways. To routinely and accurately study the dynamics of BCAAs and BCKAs in human diseases, e.g. cerebral infarction, a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated. The plasma samples were deproteinized with acetonitrile, and then separated on a reversed phase C18 column with a mobile phase of 0.1 % formic acid (solvent A)-methanol (solvent B) using gradient elution. The detection of BCAAs and BCKAs was conducted in multiple reaction monitoring with positive/negative electrospray ionization switching mode. Biologically relevant isomers such as leucine and isoleucine were individually quantified by combining chromatographic separation and fragmentation. Good linearity (R (2) > 0.99) was obtained for all six analytes with the limits of detection from 0.1 to 0.2 µg/mL. The intra-day and inter-day accuracy ranged from 93.7 to 108.4 % and the relative standard deviation (RSD) did not exceed 15.0 %. The recovery was more than 80 % with RSD less than 14.0 %. The main improvements compared to related, state-of-the-art methods included enhanced sensitivity, enhanced separation of isomers, and reduced complexity of sample processing. Finally, the validated method was applied to analyze the plasma samples of healthy volunteers and patients suffering cerebral infarction, and significant differences in the concentration levels of BCAAs and BCKAs were observed.

To better understand different traditional uses of the stems (known as Mahuang) and roots (known as Mahuanggen) of Ephedra sinica, their chemical difference should be investigated. In this study, an ultra-fast liquid chromatography coupled with ion trap time-of-flight mass spectrometry untargeted metabolomics approach was established to reveal global chemical difference between Mahuang and Mahuanggen. Clear separation was observed in scores plots of principal component analysis and orthogonal partial least squares-discriminant analysis. Twenty two chemical markers responsible for such separation were screened out and unambiguously/tentatively characterized. Then chemical markers of pharmacologically important ephedrine and pseudoephedrine were absolutely quantified using liquid chromatography coupled with tandem mass spectrometry under multiple reaction monitoring mode. The results showed that Mahuang was rich in ephedrine-type alkaloids, while Mahuanggen was rich in macrocyclic spermine alkaloids. Additionally, different types of flavan-3-ols and flavones exist in Mahuang and Mahuanggen extracts. This research facilitates a better understanding of different traditional uses of Mahuang and Mahuanggen and provides references for chemical analysis of other medicinal plants., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The integration of liquid chromatography-mass spectrometry (LC-MS) with derivatization is a relatively new and unique strategy that could add value and could enhance the capabilities of LC-MS-based technologies. The derivatization process could be carried out in various analytical steps, for example, sampling, storage, sample preparation, HPLC separation, and MS detection. This review presents an overview of derivatization-based LC-MS strategy over the past 10 years and covers both the general principles and applications in the fields of pharmaceutical and biomedical analysis, biomarker and metabolomic research, environmental analysis, and food-safety evaluation. The underlying mechanisms and theories for derivative reagent selection are summarized and highlighted to guide future studies., (Copyright © 2011 Wiley Periodicals, Inc.)

Z0 ion from saikosaponins with 16 -OH and Y0-H2O from saikosaponins with 16 -OH may underlie their different dissociation patterns of [aglycone - H2O + H]+ Epimers are ubiquitous in natural products, among which SSa and SSd are a typical pair of epimers in the I Bupleurum i species. Above all, the [aglycone - H SB 2 sb O + H] SP + sp ion at I m/z i 455.35(C SB 30 sb H SB 47 sb O SB 3 sb ) of SSa and SSd in the full-scan mass spectra should mainly be the I Y i SB 0 sb -H SB 2 sb O ion and I Z i SB 0 sb ion, separately, and this may underlie their different dissociation patterns. [Extracted from the article]

Z0 ion from saikosaponins with 16 -OH and Y0-H2O from saikosaponins with 16 -OH may underlie their different dissociation patterns of [aglycone - H2O + H]+ Epimers are ubiquitous in natural products, among which SSa and SSd are a typical pair of epimers in the I Bupleurum i species. Above all, the [aglycone - H SB 2 sb O + H] SP + sp ion at I m/z i 455.35(C SB 30 sb H SB 47 sb O SB 3 sb ) of SSa and SSd in the full-scan mass spectra should mainly be the I Y i SB 0 sb -H SB 2 sb O ion and I Z i SB 0 sb ion, separately, and this may underlie their different dissociation patterns. [Extracted from the article]

Neuroinflammation is one of the driving forces of progressive neurodegeneration in Parkinson's disease (PD). The metabolomics approach has been proved highly useful in identifying potential therapeutic targets. Here, to identify inflammation‐relevant treatment targets for PD, mass spectrometry‐based untargeted metabolomics was applied to characterize metabolic changes in the striatum of mice with double‐hit PD induced by lipopolysaccharide plus 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP). Seven days after the final MPTP administration, metabolites from the purine metabolism pathway, including adenosine, 1‐methyladenosine, adenine, inosine, hypoxanthine, xanthine, xanthosine, and guanosine, were found to be significantly dysregulated. The metabolite–protein interaction network and changes in the concentration ratio of these metabolites indicated that adenosine and adenosine deaminase (ADA; EC 3.5.4.4) were the most promising therapeutic targets and adenosine augmentation might be a rational approach to slow PD progression. These findings were then verified in a subacute MPTP‐induced PD mouse model treated with ADA inhibition alone or in conjunction with antagonism of adenosine A2A receptors (A2AR). Behavioral, biochemical, and immunohistochemical analysis demonstrated that ADA inhibition significantly ameliorated the MPTP‐mediated motor disabilities, dopamine depletion, and dopaminergic cell death. Significantly enhanced neuroprotective effects were further observed when the ADA inhibitor was utilized in conjunction with an A2AR antagonist. Together, our study indicated for the first time that ADA inhibitors protected against neurodegeneration induced by the neurotoxin MPTP, and ADA inhibitors in combination with A2AR antagonists showed additive antiparkinsonian effects. [ABSTRACT FROM AUTHOR]

Rationale: Discriminating between aglycone‐substituted and saccharide‐substituted saikosaponins by liquid chromatography/tandem mass spectrometry (LC/MSn) is a long‐standing issue that is still to be resolved. It is necessary to characterize the two types of substituted saikosaponins taking into consideration the potential significant difference in their bioactivity. Methods: Taking the substituents malonyl and acetyl as examples, we developed a MS strategy to discriminate between the aglycone‐substituted and saccharide‐substituted saikosaponins through comparing their Y0 − nH2O (n = 1–2) ions from the protonated molecules in the full‐scan mass spectra and their B ions in the MS2 spectra of sodium‐adduct molecules in the positive mode. Results: The deprotonated molecules of the aglycone‐substituted saikosaponins presented similar fragmentation patterns to those of saccharide‐substituted ones in the negative mode, which could not discriminate whether the substitutes were located on the aglycone or the saccharide. In contrast, the Y0 − nH2O (n = 1–2) ions containing or no substituent were observed respectively in the mass fragmentation of the protonated molecules of aglycone‐substituted or saccharide‐substituted saikosaponins in the positive mode. In addition, the B ions containing or no substituent were observed respectively in the mass fragmentation of the sodium‐adduct molecules of the saccharide‐substituted or aglycone‐substituted saikosaponins in the positive mode. Two aglycone‐malonylated saikosaponins were reported for the first time. Conclusions: Whether the substituents were located on the aglycone or the saccharide could be determined according to the Y0 − nH2O (n = 1–2) ions from the protonated molecules in the full‐scan mass spectra and the B ions in the MS2 spectra of sodium‐adduct molecules in the positive mode. Our results have updated the mass fragmentation patterns of substituted saikosaponins, which is helpful for the quality control of pharmaceutical preparations containing saikosaponins. More importantly, this MS strategy should be able to be extended to characterize other substituted saponins of bioactive significance in future studies. [ABSTRACT FROM AUTHOR]

Crude rhubarb subjected to different processing procedures will produce different therapeutic effects that are possibly due to processing-induced variation in chemical composition. In this study, a chemometric approach based on ultra fast liquid chromatography with ion trap/time-of-flight mass spectrometry was established to systematically investigate the chemical variations of rhubarb induced by different processing methods. The approach was validated based on pooled quality-control samples from two perspectives: the individual properties of variables and the bulk properties of samples. Orthogonal partial least squares discriminant analysis was introduced to compare the differences between crude and processed rhubarb products. A total of 20 significantly different markers were screened out and unambiguously/tentatively characterized. This research proved that a chemometric method based on ultra fast liquid chromatography with ion trap/time-of-flight mass spectrometry can comprehensively analyze the chemical variation of herbal medicine and provide evidence for a deeper understanding of the pharmacological activities of processed rhubarb products. [ABSTRACT FROM AUTHOR]

As a specific item mentioned in traditional Chinese medicine theory, processing can fulfill different requirements of therapies. Crude and wine-processed rhubarbs are used as drastic and mild laxatives, respectively. In this study, a practical method based on ultra-fast liquid chromatography coupled with diode-array detection and ion trap time-of-flight mass spectrometry was developed to screen and analyze multiple absorbed bioactive components and metabolites in the serum of both normal and acute blood stasis rats after oral administration of crude or wine-processed rhubarbs. A total of 16 compounds, mainly including phase II metabolites, were tentatively identified. Possible explanations for the processing-induced changes in pharmacological effects of traditional Chinese medicines were first explored at serum pharmacochemistry level. [ABSTRACT FROM AUTHOR]

Da-Cheng-Qi decoction (DCQT) is a traditional purgative Chinese decoction with a history of 2000 years. To study the effect of interactions between the ingredients on the overall chemical composition of DCQT, a chemomic and chemometric approach based on ultra-fast liquid chromatography with ion trap time-of-flight mass spectrometry was developed and validated. After mixing and decocting all four ingredients to make the DCQT, the concentrations of some chemicals are significantly different from those in single herb decoction and 24 of them were identified and tentatively characterized by comparing their data with those of standard compounds or literature data. No new chemicals were formed during mixing and decoction. Our findings indicated that there are interactions between these natural medicines during the mixing and preparation process. The 24 identified chemicals could be used as chemical markers for optimizing prescription and evaluation of consistent quality, and the strategy in the present study could be applied for other multiherb formulae. [ABSTRACT FROM AUTHOR]

Artificial Calculus Bovis is a major substitute in clinical treatment for Niuhuang, a widely used, efficacious but rare traditional Chinese medicine. However, its chemical structures and the physicochemical properties of its components are complicated, which causes difficulty in establishing a set of effective and comprehensive methods for its identification and quality control. In this study, a simple, sensitive and reliable liquid chromatography–tandem mass spectrometry method was successfully developed and validated for the simultaneous determination of bilirubin, taurine and major bile acids (including six unconjugated bile acids, two glycine-conjugated bile acids and three taurine-conjugated bile acids) in artificial Calculus Bovis using a Zorbax SB-C18 column with a gradient elution of methanol and 10 mmol/L ammonium acetate in aqueous solution (adjusted to pH 3.0 with formic acid). The mass spectra were obtained in the negative ion mode using dehydrocholic acid as the internal standard. The content of each analyte in artificial Calculus Bovis was determined by monitoring specific ion pairs in the selected reaction monitoring mode. All analytes demonstrated perfect linearity (r2 > 0.994) in a wide dynamic range, and 10 batches of samples from different sources were further analyzed. This study provided a comprehensive method for the quality control of artificial Calculus Bovis. [ABSTRACT FROM PUBLISHER]

• A chemical labeling-based LC-MS/MS method for the MVA pathway intermediates is established. • Mass spectrum calculation enables the quantification of isomers of IPP and DMAPP. • Novel MVA analogs are identified for the first time. The mevalonate (MVA) pathway plays a crucial role in the occurrence and progression of various diseases, such as osteoporosis, breast cancer, and lung cancer, etc. However, determining all the MVA pathway intermediates is still challenging due to their high polarity, low concentration, chelation effect with metal compartments, and poor mass spectrometric response. In this study, we established a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method coupled with N2, N2, N4, N4 -tetramethyl-6-(4-(piperazin-1-ylsulfonyl) phenyl)-1,3,5-triazine-2,4-diamine (Tmt-PP) labeling for the simultaneous analysis of all MVA intermediates in biospecimens. Chemical derivatization significantly improved the chromatographic retention, peak shape, and detection sensitivity of the analytes. Moreover, we employed a method named mass spectrum calculation to achieve the absolute quantification of the isomers, i.e., isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP). The established method was fully qualified and applied to explore the difference of these metabolites in cisplatin-resistant non-small cell lung cancer (NSCLC) cells. Additionally, several MVA intermediate analogs, including isopentenyl monophosphate or dimethylallyl monophosphate (IMP/DMAMP), geranyl monophosphate (GMP), 5-triphosphomevalonate (MTP), and isopentenyl triphosphate or dimethylallyl triphosphate (ITP/DMATP), were identified for the first time using a knowledge-driven prediction strategy. We further explored the tissue distribution of these novel metabolites. Overall, this work developed a sensitive quantification method for all MVA intermediates, which will enhance our understanding of the role of this pathway in various health and disease conditions. The novel metabolites we discovered warrant further investigations into their biosynthesis and biological functions. [Display omitted] [ABSTRACT FROM AUTHOR]

The formidable challenge posed by the presence of extremely high amounts of compounds and large differences in concentrations in plasma significantly complicates non-targeted metabolomics analyses. In this study, a comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GC×GC-qMS) method with a solid-state modulator (SSM) for non-targeted metabolomics in beagle plasma was first established based on a GC-MS method, and the qualitative and quantitative performance of the two platforms were compared. Identification of detected compounds was accomplished utilizing NIST database match scores, retention indices (RIs) and standards. Semi-quantification involved the calculation of peak area ratios to internal standards. Metabolite identification sheets were generated for plasma samples on both analytical platforms, featuring 22 representative metabolites chosen for validating qualitative accuracy, and for conducting comparisons of linearity, accuracy, precision, and sensitivity. The outcomes revealed a threefold increase in the number of identifiable metabolites on the GC×GC-MS platform, with lower limits of quantitation (LLOQs) reduced to 0.5–0.05 times those achieved on the GC-MS platform. Accuracy in quantification for both GC×GC-MS and GC-MS fell within the range of 85–115%, and the vast majority of intra- and inter-day precisions were within the range of 20%. These findings underscore that relative to the conventional GC-MS method, the GC×GC-MS method developed in this study, combined with SSM, exhibits enhanced qualitative capabilities, heightened sensitivity, and comparable accuracy and precision, rendering it more suitable for non-targeted metabolomics analyses. [Display omitted] • We first introduced the SSM based GC×GC-MS method to non-targeted metabolomics. • The GC×GC-MS method provided broader coverage of metabolites than GC-MS method. • GC×GC-MS method provided higher sensitivity, comparable stability with GC-MS method. [ABSTRACT FROM AUTHOR]

Abstract: Realgar (As4S4) is a traditional medicine used in China and Europe for thousands of years. As an arsenical, the toxicity from realgar has raised public concern. Several organic acids in urine are found to be potential biomarkers of realgar exposure, including taurine, citric, glutamic, lactic, pyruvic, succinic and uric acid. In this study, using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS), a rapid and sensitive method was developed to separate and quantify these compounds in urine. A ZIC®-HILIC column was used for the separation at an isocratic condition of acetonitrile and 10mM ammonium acetate in water. Analytes were detected in multiple-reaction monitoring with negative ionization mode, using ibuprofen as internal standard. Good line arities (R 2 >0.996) were obtained for all analytes with the limits of detection from 0.2 to 0.7μg/mL. The intra-day and inter-day accuracy ranged from 89.1 to 104.4% and the relative standard deviation (RSD) did not exceed 15.0%. The recovery was more than 80%with RSD less than 14.0%. The validated method was applied to analyze the urine samples of control and reaglar treated rats, and significant changes of these organic acids were observed. [Copyright &y& Elsevier]

Abstract: A rapid, sensitive and specific liquid chromatography-electrospray ionization/tandem mass spectrometry (LC-ESI/MS/MS) method has been developed and validated for simultaneous determination of five active constituents (including magnolol, honokiol, rhein, emodin and aloe-emodin) from Da-Cheng-Qi decoction (DCQD) in rat plasma. After the addition of gliquidone as the internal standard (IS), plasma samples were prepared by one-step protein precipitation using methanol and separated by HPLC on a short reversed phase C18 column packed with smaller particles (100mm×3.0mm, 3.5μm) using a mobile phase of methanol–0.1% formic acid aqueous solution (70:30, v/v). Analytes were determined in a triple-quadrupole mass spectrometer in the selected reaction-monitoring (SRM) mode using electrospray source with negative mode. The method was proved to be rapid, sensitive, specific, accurate and reproducible and has been successfully applied to the determination of the five compounds in rat plasma after oral administration of low dose DCQD for pharmacokinetic study. [Copyright &y& Elsevier]

Abstract: A selective and sensitive high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (ESI-MS/MS) method for simultaneous determination of metformin and rosiglitazone in human plasma using phenformin as internal standard (IS) has been first developed and validated. Plasma samples were precipitated by acetonitrile and the analytes were separated on a prepacked Phenomenex Luna 5u CN 100A (150mm×2.0mm I.D.) column using a mobile phase comprised of methanol:30mM ammonium acetate pH 5.0 (80:20, v/v) delivered at 0.2ml/min. Detection was performed on a Finnigan TSQ triple-quadrupole tandem mass spectrometer in positive ion selected reaction monitoring (SRM) mode using electrospray ionization. The ion transitions monitored were m/z 130.27→71.11 for metformin, m/z 358.14→135.07 for rosiglitazone and m/z 206.20→105.19 for the IS. The standard curves were linear (r 2 >0.99) over the concentration range of 5–3000ng/ml for metformin and 1.5–500ng/ml for rosiglitazone with acceptable accuracy and precision, respectively. The within- and between-batch precisions were less than 15% of the relative standard deviation. The limit of detection (LOD) of both metformin and rosiglitazone was 1ng/ml. The method described is precise and sensitive and has been successfully applied to the study of pharmacokinetics of compound metformin and rosiglitazone capsules in 12 healthy Chinese volunteers. [Copyright &y& Elsevier]

• A progressive strategy was developed to targeted detect the metabolites of saikogenins in rat plasma and feces. • Seventy-one metabolites of saikogenins were identified in rat and human microsomes by HPLC-IT/TOF-MS. • The monohydroxylation or carboxylation is the major metabolic pathway both in vitro and in vivo. • The metabolic profile of saikogenins both in vitro and in vivo were firstly investigated. Saikosaponins are the representative bioactive ingredient in the Radix Bupleuri. Previous studies have reported that saikosaponins are prone to losing their glycones and being converted to corresponding prosaikogenins and saikogenins by intestinal bacteria. However, the microsomal cytochrome P450-mediated metabolism of these deglycosylated metabolites is still unknown. This research performed in vitro studies of five saikogenins in rat and human liver microsomes. High-performance liquid chromatography coupled with a hybrid ion trap and time-of-flight mass spectrometry (HPLC-IT/TOF-MS) was employed to identify the metabolites. To confirm the metabolites detected in vitro , plasma and feces obtained from rats administrating several saikogenins were also analyzed by high-performance liquid chromatography with triple-quadrupole mass spectrometry (HPLC-QqQ-MS). The in vitro metabolic stability of saikogenins was ranked as follows: SGF＞SGG＞SGE＞SGA＞SGD. A total of 71 metabolites generated by hydroxylation, carboxylation, and dehydrogenation, as well as combinations of these steps, were identified by accurate mass measurement and MSn fragmentation behavior. Among eight metabolic pathways, monohydroxylation or carboxylation was the major metabolic pathway both in vitro and in vivo. Analysis of in vivo biological samples suggested that analytical targets for saikogenins should be the compounds themselves and their oxidized metabolites. This research provides a basis for further studies of the in vivo metabolism of saikosaponins in humans. [ABSTRACT FROM AUTHOR]

Data reduction techniques in gas chromatography-mass spectrometry-based untargeted metabolomics has made the following workflow of data analysis more lucid. However, the normalization process still perplexes researchers, and its effects are always ignored. In order to reveal the influences of normalization method, five representative normalization methods (mass spectrometry total useful signal, median, probabilistic quotient normalization, remove unwanted variation-random, and systematic ratio normalization) were compared in three real data sets with different types. First, data reduction techniques were used to refine the original data. Then, quality control samples and relative log abundance plots were utilized to evaluate the unwanted variations and the efficiencies of normalization process. Furthermore, the potential biomarkers which were screened out by the Mann-Whitney U test, receiver operating characteristic curve analysis, random forest, and feature selection algorithm Boruta in different normalized data sets were compared. The results indicated the determination of the normalization method was difficult because the commonly accepted rules were easy to fulfill but different normalization methods had unforeseen influences on both the kind and number of potential biomarkers. Lastly, an integrated strategy for normalization method selection was recommended. [ABSTRACT FROM AUTHOR]

Astragali Radix (AR) is a popular traditional Chinese medicine that has been used for more than 2000 years. It is a well-known tonic for weak people with chronic diseases, such as heart failure and cerebral ischemia. Previous studies have reported that AR could support the "weak heart" of cancer patients who suffered from doxorubicin (DOX)-induced cardiotoxicity (DIC). However, the underlying mechanism remains unclear. This study aimed to uncover the critical pathways and molecular determinants for AR against DIC by fully characterizing the network-based relationship. We integrated ultra-high-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) profiling, database and literature searching, and the human protein-protein interactome to discover the specific network module associated with AR against DIC. To validate the network-based findings, a low-dose, long-term DIC mouse model and rat cardiomyoblast H9c2 cells were employed. The levels of potential key metabolites and proteins in hearts and cells were quantified by the LC-MS/MS targeted analysis and western blotting, respectively. We constructed one of the most comprehensive AR component-target network described to date, which included 730 interactions connecting 64 unique components and 359 unique targets. Relying on the network-based evaluation, we identified fatty acid metabolism as a putative critical pathway and peroxisome proliferator-activated receptors (PPARα and PPARγ) as potential molecular determinants. We then confirmed that DOX caused the accumulation of fatty acids in the mouse failing heart, while AR promoted fatty acid metabolism and preserved heart function. By inhibiting PPARγ in H9c2 cells, we further found that AR could alleviate DIC by activating PPARγ to maintain fatty acid homeostasis. Our findings imply that AR is a promising drug candidate that treats DIC by maintaining fatty acid homeostasis. More importantly, the network-based method developed here could facilitate the mechanism discovery of AR therapy and help catalyze innovation in its clinical application. [Display omitted] • A network-based method was developed to explore the mechanism of AR against DIC. • Network analysis identified fatty acid metabolism as a putative curial pathway. • AR preserved heart function and promoted fatty acid metabolism on DIC mouse model. • AR alleviates DIC by stimulated PPARγ and then maintained fatty acid homeostasis. [ABSTRACT FROM AUTHOR]

Abstract: A rapid and sensitive method based on liquid chromatography–tandem mass spectrometry (LC–MS/MS) for the simultaneous determination of codeine, ephedrine, guaiphenesin and chlorpheniramine in beagle dog plasma has been developed and validated. Following liquid–liquid extraction, the analytes were separated on a reversed-phase C18 column (150mm×2.0mm, 3μm) using formic acid:10mM ammonium acetate:methanol (0.2:62:38, v/v/v) as mobile phase at a flow rate of 0.2mL/min and analyzed by a triple-quadrupole mass spectrometer in the selected reaction monitoring (SRM) mode. The method was linear for all analytes over the following concentration (ng/mL) ranges: codeine 0.08–16; ephedrine 0.8–160; guaiphenesin 80–16,000; chlorpheniramine 0.2–40. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. It is the first time that the validated HPLC–MS/MS method was successfully applied to a bioequivalence study in 6 healthy beagle dogs. [Copyright &y& Elsevier]

Abstract: High-performance liquid chromatography with diode-array detection (HPLC–DAD) and tandem mass spectrometry (HPLC–MS/MS) was used for separation and identification of metabolites in rat urine, bile and plasma after oral administration of rhubarb decoction. Based on the proposed strategy, 91 of the 113 potential metabolites were tentatively identified or characterized. Besides anthraquinones metabolites, gallic acid, (−)-epicatechin and (+)-catechin metabolites were also detected and characterized in these biological samples. Our results indicated that glucuronidation and sulfation were the main metabolic pathways of anthraquinones, while methylation, glucuronidation and sulfation were the main metabolic pathways of gallic acid, (−)-epicatechin and (+)-catechin. Phase I reactions (e.g., hydroxylation and reduction) played a relatively minor role compared to phase II reactions in metabolism of phenolic compounds of rhubarb decoction. The identification and structure elucidation of these metabolites provided essential data for further pharmacological and clinical studies of rhubarb and related preparations. Moreover, the results of the present investigations clearly indicated the relevance and usefulness of the combination of chromatographic, spectrophotometric, and mass-spectrometric analysis to detect and identify metabolites. [ABSTRACT FROM AUTHOR]

Abstract: A simple, rapid, sensitive and selective liquid chromatographic–tandem mass spectrometric (LC–MS/MS) method was developed and validated for the quantification of rupatadine in human plasma using estazolam as internal standard (IS). Following liquid–liquid extraction, the analytes were separated using a mobile phase of methanol–ammonium acetate (pH 2.2; 5mM) (50:50, v/v) on a reverse phase C18 column and analyzed by a triple-quadrupole mass spectrometer in the positive ion and multiple reaction monitoring (MRM) mode, m/z 416→309 for rupatadine and m/z 295→267 for the IS. The assay exhibited a linear dynamic range of 0.1–100ng/ml for rupatadine in human plasma. The lower limit of quantification (LLOQ) was 0.1ng/ml with a relative standard deviation of less than 20%. Acceptable precision and accuracy were obtained for concentrations over the standard curve range. The validated LC–MS/MS method has been successfully applied to study the pharmacokinetics of rupatadine in healthy volunteers. [Copyright &y& Elsevier]

Abstract: A preparative high-speed counter-current chromatography (HSCCC) method for separation and purification of phenolic acids from the Chinese medicinal herb Smilax china was successfully established by using n-hexane–ethyl acetate–methanol–water (1:2:1:2, v/v/v/v) as the two-phase solvent system. The experiment yielded 26.7mg of gallic acid, 16.5mg of protocatechuic acid, 21.8mg of caffeic acid, 31.3mg of gentisic acid, and 24.1mg of trans-o-coumaric acid from 250mg of crude extract in one-step separation, of each at over 98% purity as determined by high-performance liquid chromatography (HPLC). The structures of these compounds were identified by electron spray ionization mass spectroscopy (ESI-MS), 1H and 13C nuclear magnetic resonance (NMR). [Copyright &y& Elsevier]