LTQ-Orbitrap Mass Spectrometry Research Articles

Curcuma wenyujin rhizomes extract ameliorates lipid accumulation

Curcuma wenyujin (C. wenyujin) is a medicinal plant that is traditionally used to treat blood stagnation, liver fibrosis, pain, and jaundice. In this study, we examined the effect of C. wenyujin rhizome extract on hepatic lipid accumulation both in vivo and in vitro. We found that the petroleum ether fraction of C. wenyujin rhizome extract (CWP) considerably reduced the accumulation of lipids in HepG2 cells treated with oleic and palmitic acid. Ultra-high-performance liquid chromatography coupled with LTQ-Orbitrap mass spectrometry was used to analyze the main chemical constituents of CWP, and 21 sesquiterpenes were identified. In vivo experiments revealed that the administration of CWP significantly reduced the body weight and serum total cholesterol (TC) level of low-density-lipoprotein receptor knockout mice treated with a high-fat diet without affecting their food intake. CWP also significantly reduced the levels of liver TC, liver triglycerides, aspartate transaminase, and alanine transaminase. Histological examination revealed that CWP dose-dependently reduced steatosis in liver tissue, significantly downregulated the expression of lipogenesis genes, and increased the β-oxidation of fatty acids. CWP also significantly increased autophagy-related proteins. In conclusion, CWP rich in sesquiterpenes reduces the accumulation of lipids in vivo and in vitro by improving lipid metabolism and activating autophagy.

Validation of high-performance liquid chromatography coupled with LTQ orbitrap mass spectrometry for analysis of acrylamide

Validation of high-performance liquid chromatography coupled with LTQ orbitrap mass spectrometry for analysis of acrylamide

Polyunsaturated Fatty Acids Mend Macrophage Transcriptome, Glycome, and Phenotype in the Patients with Neurodegenerative Diseases, Including Alzheimer's Disease.

Macrophages of healthy subjects have a pro-resolution phenotype, upload amyloid-β (Aβ) into endosomes, and degrade Aβ, whereas macrophages of patients with Alzheimer's disease (AD) generally have a pro-inflammatory phenotype and lack energy for brain clearance of Aβ. To clarify the pathogenesis of sporadic AD and therapeutic effects of polyunsaturated fatty acids (PUFA) with vitamins B and D and antioxidants on monocyte/macrophage (MM) migration in the AD brain, MM transcripts in energy and Aβ degradation, MM glycome, and macrophage clearance of Aβ. We followed for 31.3 months (mean) ten PUFA-supplemented neurodegenerative patients: 3 with subjective cognitive impairment (SCI), 2 with mild cognitive impairment (MCI), 3 MCI/vascular cognitive impairment, 2 with dementia with Lewy bodies, and 7 non-supplemented caregivers. We examined: monocyte migration in the brain and a blood-brain barrier model by immunochemistry and electron microscopy; macrophage transcriptome by RNAseq; macrophage glycome by N-glycan profiling and LTQ-Orbitrap mass spectrometry; and macrophage phenotype and phagocytosis by immunofluorescence. MM invade Aβ plaques, upload but do not degrade Aβ, and release Aβ into vessels, which develop cerebrovascular amyloid angiopathy (CAA); PUFA upregulate energy and Aβ degradation enzyme transcripts in macrophages; PUFA enhance sialylated N-glycans in macrophages; PUFA reduce oxidative stress and increase pro-resolution MM phenotype, mitochondrial membrane potential, and Aβ phagocytosis (p < 0.001). Macrophages of SCI, MCI, and AD patients have interrelated defects in the transcriptome, glycome, Aβ phagocytosis, and Aβ degradation. PUFA mend macrophage transcriptome, enrich glycome, enhance Aβ clearance, and benefit the cognition of early-stage AD patients.

Determination of multiple active constituents in Da‐Huang‐Xiao‐Shi decoction using HPLC–LTQ–Orbitrap mass spectrometry: Application in comparing the differences in the formula and its constituent herbs

Da-Huang-Xiao-Shi decoction (DHXSD) is a traditional Chinese medicine formula and is used to treat cholestasis. In this study, we developed a reliable and comprehensive HPLC coupled with a linear ion trap-Orbitrap mass spectrometry method for the separation and determination of 21 components including six alkaloids, five anthraquinones, three tannins, three terpenes, two iridoid glycosides, one organic acid and one flavonoid in DHXSD. A C18 column was eluted using a gradient mobile phase at a flow rate of 1ml/min. Detection was operated with an electrospray ionization source in positive and negative ion modes using selective ion monitoring. The calibration curves for all analytes showed good linearity (r > 0.9901), and the inter- and intra-day precision did not exceed 4.98%. The recovery, repeatability and stability were also within the acceptable limits. The method was successfully applied to determine multiple active constituents in DHXSD and its constituent herbs. Compared with Da Huang, the total contents of the five anthraquinones were significantly higher in DHXSD. However, the changes in the components from Zhi Zi/Huang Bo were complicated in DHXSD. The study could serve as a fundamental reference for establishing comprehensive DHXSD quality control measures and be helpful to understand some compatibility laws of DHXSD.

Quantitative proteomic analysis comparing grades ICRS1 and ICRS3 in patients with osteoarthritis.

Osteoarthritis (OA), which is caused by joint damage, is the most common form of arthritis, affecting millions of people worldwide. This damage can accumulate over time, which is why aging is one of the main contributors to joint damage associated with OA. The OA-related proteins that have been reported to date have been identified by the comparative analysis of OA patients with normal controls, following surgical or pharmacological treatment. For the first time, the present study analyzed OA-related proteins in patients with OA according to the International Cartilage Repair Society (ICRS) scale. Changes in protein expression can be observed during the OA process. The present study demonstrated differential protein expression patterns in articular cartilage from ICRS1- and ICRS3-graded OA patients. ICRS grade-matched OA knee samples from 12 OA patients, 6 ICRS grade 1 patients and 6 ICRS3 patients were subjected to proteomic analysis using the LTQ-Orbitrap mass spectrometry system. A total of 231 unique proteins were identified as expressed across the ICRS1 and ICRS3 OA patient groups. Relative differences in protein expression associated with the following classifications were observed: Biological adhesion, cell killing, cellular process, development process and molecular function. Although some of these proteins have been previously reported to be associated with rheumatoid arthritis, including cartilage oligomeric matrix protein, collagen types, angiogenin, complement C5 and CD59 glycoprotein, numerous additional proteins were newly identified, which may further help our understanding of disease pathogenesis. These findings suggested that these proteins may be used to develop novel therapeutic targets for OA.

Pilot-plant scale extraction of phenolic compounds from grape canes: Comprehensive characterization by LC-ESI-LTQ-Orbitrap-MS

Grape canes, also named vine shoots, are well-known viticultural byproducts containing high levels of phenolic compounds, which are associated with a broad range of health benefits. In this work, grape canes (Vitis vinifera cv. Pinot noir) were extracted in a 750 L pilot-plant reactor under the following conditions: temperature 80 °C, time 100 min, solid/liquid ratio 1:10. The comprehensive characterization of grape cane phenolic compounds was performed by liquid chromatography coupled to high-resolution/accurate mass measurement LTQ-Orbitrap mass spectrometry. A total of 44 compounds were identified and, 26 of them also quantified, consisting of phenolic acids and aldehydes (17), flavonoids (12), and stilbenoids (15). The most abundant class of phenolics were stilbenoids, among which (E)-ε-viniferin predominated. The phenolic profile of grape canes obtained using pilot plant extraction differed significantly from the results of laboratory-scale studies obtained previously. Additionally, we observed a high antioxidant capacity of grape cane pilot-plant extract measured by the radical antioxidant scavenging potential (ABTS+) (2209 ± 125 µmol TE/g DW) and oxygen radical absorbance capacity using fluorescein (ORAC-FL) (4612 ± 155 µmol TE/g DW). Grape cane pilot-plant extract for their phenolic profile may be used as a by-product for the development of novel nutraceutical and pharmaceutical products, improving the value and the sustainability of these residues.

Metabolomics Combined with Multivariate Statistical Analysis for Screening of Chemical Markers between Gentiana scabra and Gentiana rigescens.

Gentianae Radix et Rhizome (Longdan in Chinese, GRR) in Chinese Pharmacopoeia is derived from the dried roots and rhizomes of Gentiana scabra and G. rigescens, that have long been used for heat-clearing and damp-drying in the medicinal history of China. However, the characterization of the chemical components of two species and the screening of chemical markers still remain unsolved. In current research, the identification and characterization of chemical components of two species was performed using ultra-high-performance liquid chromatography (UHPLC) coupled with linear ion trap-Orbitrap (LTQ-Orbitrap) mass spectrometry. Subsequently, the chemical markers of two species were screened based on metabolomics and multivariate statistical analysis. In total, 87 chemical constituents were characterized in G. scabra (65 chemical constituents) and G. rigescens (51 chemical constituents), with 29 common chemical constituents being discovered. Thereafter, 11 differential characteristic components which could differentiate the two species were designated with orthogonal partial least squares discriminant analysis (OPLS-DA) and random forest (RF) iterative modeling. Finally, seven characteristic components identified as (+)-syringaresinol, lutonarin, trifloroside, 4-O-β-d-glu-trifloroside, 4″-O-β-d-glucopyranosy1-6′-O-(4-O-β-d-glucaffeoyl)-linearroside, macrophylloside a and scabraside were selected as the chemical markers for the recognition of two Gentiana species. It was implied that the results could distinguish the GRR derived from different botanical sources, and also be beneficial in the rational clinical use of GRR.

Bioactive constituents of Lobostemon fruticosus: Anti-inflammatory properties and quantitative analysis of samples from different places in South Africa

Lobostemon fruticosus is South Africa medicinal plant traditionally used in treatment of wounds and skin diseases. Nevertheless, there is no report on its phytochemical constituents. LC–LTQ-Orbitrap mass spectrometry was used for identification and quantification of its constituents. A total of 13 compounds were identified from the leaves and twigs of the plant using NMR, ESI-HRMS and reference substances. The identified compounds were p-hydroxybenzoic acid (1), lycopsamine-N-oxide (2), caffeic acid (3), loliolide (4), 3-indolcarbaldehyde (5), globoidnan B (6), rabdosiin (7), syringaresinol (8), pinoresinol (9), rutin (10), rosmarinic acid (11), keampferol-3-O-rutinoside (12) and globoidnan A (13). In addition, quantitative determination of 6 marker compounds in samples from 12 different locations in South Africa was established. Rosmarinic acid and globoidnan A were found in large amount in the leaves and flowers of the plant. Samples from West Cape contained relatively greater amount of the tested compounds per dry weight than the other samples. The anti-inflammatory activities of isolated compounds were assessed by measuring the levels of cytokines IL-1β, IL-2, IL-6, GM-CSF and TNF-α in the supernatant media of human peripheral blood mononuclear cells (PBMCs) stimulated by lipopolysaccharide (LPS). At a concentration of 100 μM, compounds 7, 8 and 11 significantly decreased secretion of IL-1β, IL-2 and IL-6 compared to the LPS treated control (0.76–57.6%). All compounds significantly reduced the production of TNF-alpha compared to the LPS treated control (0.17–12.2%) and reference drug ibuprofen.

Application of MALDI-mass spectrometry imaging in spatial distribution of secondary metabolites in medicinal plants -- a case study of Lepdium meyenii root

Matrix-assisted laser desorption/ionization mass spectrometry imaging(MALDI-MSI) is a novel technique for in-situ distribution of various substances in tissue without labeling. This technique is increasingly applied to the study of medicinal plants owing to its high spatial resolution and its potential of in-situ analysis in small molecules. In this study, the structural information and their fragmentation patterns of the midazole alkaloids(1,3-dibenzyl-4,5-dimethylimidazolium chloride and 1,3-dibenzyl-2,4,5-trimethylimi-dazolium chloride) and benzylglucosinolate in the medicinal plant Maca(Lepdium meyeni) root were analyzed by ultra-high-performance liquid phase combined with LTQ-Orbitrap mass spectrometry(UHPLC-HR-MS). The localization of these active ingredients in the cross-sections of Maca root was performed by MALDI-MSI. These results demonstrated that the two types of imidazole alkaloids had a similar distributed pattern. They were located more in the cortex and the periderm than those in the medulla of a lateral root, while the localization of benzylglucosinolate was concentrated in the center of the root rather than in the cortex and the periderm. The precise spatial distribution of various secondary metabolites in tissue provides an important scientific basis for the accumulation of medicinal plant active ingredients in tissues. In addition, this imaging method is a promising technique for the rapid evaluation and identification of the active ingredients of traditional Chinese medicine in plant tissues, as well as assisting the research on the processing of medicinal plants.

Discovery and validation of peptide biomarkers for discrimination of Dendrobium species by label-free proteomics and chemometrics

The stems of Dendrobium officinale, a well-known and expensive food material and herbal medicine in Asia, has recently suffered adulterants and counterfeits by using lower-price confusing Dendrobium species such as D. devonianum or D. transparens in the herbal market. However, robust methods that could authenticate D. officinale from its confusing species effectively are still lacking, especially for the dried samples. This study committed to discover specific peptides biomarkers for the authentication of D. officinale from the other two Dendrobium species using label-free proteomics by nanoLC LTQ Orbitrap mass spectrometry. Multivariate statistical analysis was applied to visualize the difference between the three Dendrobium species. As a result, 29 peptides among a total of 343 measurable peptides were selected to be potential biomarkers for the classification of these Dendrobium species. The validation of the representative peptide biomarkers was carried out by the synthesized peptides and 3 peptide biomarkers were found significant for the authentication of D. officinale. Further analysis showed that peptide ALGLELDLSER may also be a biomarker for the discrimination of the D. officinale originated from different geographical regions.

Qualitative and quantitative determination of Atractylodes rhizome using ultra-performance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometry with data-dependent processing.

A quick and effective workflow based on ultra-performance liquid chromatography coupled with electron spray ionization and LTQ-Orbitrap mass spectrometry (UPLC-LTQ-Orbitrap MS) was established for compositional analysis and screening of the characteristic compounds of three species of Atractylodes rhizome for quality evaluation. This technique was employed to determine the seven main components in Atractylodes rhizome samples. Ultimately, 78 constituents were identified; of these, seven characteristic compounds were selected for species discrimination, comprising atractylodin (63), atractylenolide I (43), atractylenolide II (49), atractylenolide III (53), atractylon (69), methyl-atractylenolide II (54) and (4E,6E,12E)-tetradecadecatriene-8,10-diyne-1,3-diacetate (59). The seven main compounds, including six characteristic compounds, were simultaneously determined in 29 batches of Atractylodes rhizome samples. Thus, the method validation showed acceptable results. Quantitative analysis showed significantly different contents of the seven main components among the three species of Atractylodes rhizome, which indicates possible distinctions in the pharmacological effects. This established method can simultaneously provide qualitative and quantitative results for compositional characterization of Atractylodes rhizomes and for quality control.

Thymosin fraction 5 re-evaluated after 35 years by high-resolution mass spectrometry

ABSTRACTObjectives: We reevaluated a lyophilized sample of thymosin fraction 5, stored for 37 years at room temperature, by high-resolution mass spectrometry in terms of stability and yet uncharacterized polypeptides that could be biological important substances.Methods: A top–down proteomic platform based on high-performance liquid chromatography (HPLC) coupled to high-resolution LTQ-Orbitrap mass spectrometry (MS) was applied to molecular characterization of polypeptides present in thymosin fraction 5.Results: We detected more than 100 monoisotopic masses corresponding to thymosin β4 and truncated forms of ubiquitin, prothymosin α, thymosin β4, and thymosin β9. Additionally, we discovered a new polypeptide present in thymosin fraction 5 and identified it as intact SH3 domain-binding glutamic acid-rich-like protein 3.Conclusion: In spite of the well-known proteolytic processes inherent to the preparation of thymosin fraction 5, still uncharacterized polypeptides as well as truncated forms of already well-known thymosins are present in fraction 5 after long-term storage. Therefore, continuing characterization of thymosin fraction 5 is even nowadays highly promising.

Multi-component identification and target cell-based screening of potential bioactive compounds in toad venom by UPLC coupled with high-resolution LTQ-Orbitrap MS and high-sensitivity Qtrap MS.

Traditional Chinese medicines (TCMs) are undoubtedly treasured natural resources for discovering effective medicines in treating and preventing various diseases. However, it is still extremely difficult for screening the bioactive compounds due to the tremendous constituents in TCMs. In this work, the chemical composition of toad venom was comprehensively analyzed using ultra-high performance liquid chromatography (UPLC) coupled with high-resolution LTQ-Orbitrap mass spectrometry and 93 compounds were detected. Among them, 17 constituents were confirmed by standard substances and 8 constituents were detected in toad venom for the first time. Further, a compound database of toad venom containing the fullest compounds was further constructed using UPLC coupled with high-sensitivity Qtrap MS. Then a target cell-based approach for screening potential bioactive compounds from toad venom was developed by analyzing the target cell extracts. The reliability of this method was validated by negative controls and positive controls. In total, 17 components in toad venom were discovered to interact with the target cancer cells. Further, in vitro pharmacological trials were performed to confirm the anti-cancer activity of four of them. The results showed that the six bufogenins and seven bufotoxins detected in our research represented a promising resource to explore bufogenins/bufotoxins-based anticancer agents with low cardiotoxic effect. The target cell-based screening method coupled with the compound database of toad venom constructed by UPLC-Qtrap-MS with high sensitivity provide us a new strategy to rapidly screen and identify the potential bioactive constituents with low content in natural products, which was beneficial for drug discovery from other TCMs. ᅟ Graphical abstract.

The proteome of fetal fluids in mares with experimentally-induced placentitis

IntroductionPlacental inflammation (placentitis) is one of the leading causes of late-term abortion in mares. Although prognosis is good assuming early diagnosis and treatment, diagnostics are limited. MethodsTo better characterize the disease and identify potential biomarkers, we analyzed the proteome of fetal fluids (amniotic and allantoic) in both control mares (n = 5) and mares with experimentally-induced placentitis (n = 5) using LTQ-Orbitrap mass-spectrometry. Placentitis was induced via trans-cervical inoculation of Streptococcus equi ssp. zooepidemicus. ResultsIn total, 130 proteins were identified in either amniotic fluid, allantoic fluid, or both, with amniotic proteins being more prevalent and better conserved across samples. A total of 18 proteins were up-regulated in amniotic fluid during placentitis, including haptoglobin, plasminogen isoform X2 and plasminogen-like isoform X1 which were found exclusively in samples from mares with placentitis. Five allantoic proteins were up-regulated, of which four were also found to be up-regulated in amniotic fluid, including alpha-1-antiproteinase and transferrin family members. A total of 19 proteins were down-regulated in amniotic fluid, with none decreasing significantly in allantoic fluid. DiscussionWe have performed the first proteomic analysis of amniotic and allantoic fluid during placental infection in any domestic livestock species. We identified a number of proteins with significantly altered expression, primarily those related to immune function. These findings provide information on the physiology of placentitis as well as identify potential biomarkers for future diagnostic work.

Metabolite identification of the antimalarial naphthoquine using liquid chromatography-tandem high-resolution mass spectrometry in combination with multiple data-mining tools.

Naphthoquine (NQ) is one of important partner drugs of artemisinin-based combination therapy (ACT), which is recommended for the treatment of uncomplicated Plasmodium falciparum. NQ shows a high cure rate after a single oral administration. It is absorbed quickly (time to peak concentration 2-4 h) and has a long elimination half-life (255 h). However, the metabolism of NQ has not been clarified. In this work, the metabolite profiling of NQ was studied in six liver microsomal incubates (human, cynomolgus monkey, beagle dog, mini pig, rat and CD1 mouse), seven recombinant CYP enzymes (1A2, 2B6, 2C8, 2C9, 2C19, 2D6 and 3A4) and rat (plasma, urine, bile and feces) using liquid chromatography tandem high-resolution LTQ-Orbitrap mass spectrometry (HRMSn ) in conjunction with online hydrogen/deuterium exchange. The biological samples were pretreated by protein precipitation and solid-phase extraction. For data processing, multiple data-mining tools were applied in tandem, i.e. background subtraction and followed by mass defect filter. NQ metabolites were characterized by accurate MS/MS fragmentation characteristics, the hydrogen/deuterium exchange data and cLogP simulation. As a result, five phase I metabolites (M1-M5) of NQ were characterized for the first time. Two metabolic pathways were involved: hydroxylation and N-oxidation. This study demonstrates that LC-HRMSn in combination with multiple data-mining tools in tandem can be a valuable analytical strategy for rapid metabolite profiling of drugs.

Metabolism of Rhizoma coptidis in Human Urine by Ultra-High-Performance Liquid Chromatography Coupled with High-Resolution Mass Spectrometry.

Rhizoma coptidis extract and its alkaloids were reported to exhibit various pharmacological activities. However, pharmacokinetics investigations indicated that the plasma concentrations of the alkaloids were too low to explain their systemic therapeutic actions. Thus, the metabolic profile of Rhizoma coptidis in humans is yet to be fully investigated and the present study aimed to investigate the metabolic profile of Rhizoma coptidis in human urine after oral administration of Rhizoma coptidis extract. In this study, the metabolism of Rhizoma coptidis at a clinical dose (5g/60kg/day) was investigated using ultra-high-performance liquid chromatography coupled with high-resolution LTQ-Orbitrap mass spectrometry. Totally, 30 constituents including 7 prototypes, 5 sulfation metabolites and 18 glucuronide conjugates were elucidated and identified on the basis of the characteristics of their high-resolution precursor ions, product ions, and chromatographic retention times in human urine. Among the 7 prototypes, 3 prototypes (M20, M26 and M28) were identified definitely by comparing with standards. Based on the metabolites detected in human urine, a possible metabolic pathway of Rhizoma coptidis in vivo was proposed. The results demonstrated that the metabolic fate of Rhizoma coptidis mainly involved sulfation and glucuronidation in human urine and the glucuronide conjugate M14 (berberrubinen-9-O-glucuronide) might be a pharmacokinetic marker for Rhizoma coptidis alkaloids in humans. This study will be helpful to comprehensively understand the metabolic process of Rhizoma coptidis and how Rhizoma coptidis shows its pharmacological effects in humans.

Metabolic profile of Rhizoma coptidis in human plasma determined using ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry.

Rhizoma coptidis extract and its alkaloids show various pharmacological activities, but its metabolic profile in human plasma has not been thoroughly investigated. In the present research, the metabolism of Rhizoma coptidis at a clinical dose (5g/60kg/day) was systematically analyzed to determine its biotransformation processes in human plasma. In this research, the metabolites of Rhizoma coptidis in human plasma after oral administration of Rhizoma coptidis extract at a clinical dose were investigated using ultra-high-performance liquid chromatography (UHPLC) coupled with high-resolution LTQ-Orbitrap mass spectrometry. The structural elucidation of the constituents was confirmed by comparing their retention times (tR ) and MSn fragments with those of standards and literature reports. In total, two prototypes and twelve metabolites were detected in human plasma. The two prototypes were confidently identified using reference standards. Of the compounds detected, M7 (berberrubinen-9-O-glucuronide) was the most abundant based on its peak area, which indicates that this compound might be a pharmacokinetic marker for Rhizoma coptidis alkaloids in humans. Based on the metabolites detected in human plasma, a possible metabolic pathway for Rhizoma coptidis in vivo was proposed. The results indicated that the alkaloids in Rhizoma coptidis were extensively biotransformed in vivo mainly via conjugation with glucuronic acid (GluA) or sulfuric acid (SulA) to form phase II metabolites, and the GluA metabolites are likely the dominant form in human plasma. To the best of our knowledge, this is the first in vivo evaluation of the metabolic profile of the whole Rhizoma coptidis extract in human plasma, which is essential for determining the chemicals responsible for the pharmacological activities of Rhizoma coptidis in vivo. Moreover, it would be beneficial for us to further systematically study the pharmacokinetic behavior of Rhizoma coptidis in humans.

Application of ultra-high-performance liquid chromatography coupled with LTQ-Orbitrap mass spectrometry for identification, confirmation and quantitation of illegal adulterated weight-loss drugs in plant dietary supplements.

In this paper, an ultra-high-performance liquid chromatography coupled with linear ion trap quadrupole Orbitrap high resolution mass spectrometry (UHPLC-LTQ-Orbitrap HRMS) method was developed and validated for identification, confirmation and quantitation of illegal adulterated weight-loss drugs in plant dietary supplements. 13 wt-loss drugs were well separated by the gradient elution of 10mmol/L ammonium acetate - 0.05% formic acid H2O and acetonitrile at a flow rate of 0.2mL/min within 12min. The MS analysis was operated under the positive ion and in full MS/dd-MS2 (data-dependent MS2) mode. The full MS scan with resolution at 60 000 FWHM and narrow mass windows at 5ppm acquired data for identification and quantitation, and dd-MS2 scan with resolution at 15 000 FWHM obtained product ions for confirmation. The method validation showed good linearity with coefficients of determination (r2) higher than 0.9951 for all analytes. Meantime, all the LOD and LLOQ values were in the respective range of 0.3-2 and 1-9ng/g. The accuracy, intra- and inter-day precision were in the ranges of -1.7 to 3.4%, 1.7-5.0% and 1.9-4.4%, respectively. The mean recoveries ranged from 85.4 to 107.1%, while the absolute and relative matrix effect were in the corresponding range of 98.2-108.6% and 2.6-8.7%. Among 120 batches of weight loss plant dietary supplements, sibutramine and fluoxertine or both were positive in 29 samples. In general, LTQ-Orbitrap HRMS technology was a powerful tool for the analysis of illegal ingredients in dietary supplements.

Biotransformation of NSAIDs by pig liver microsomes in vitro: Kinetics, metabolites identification and toxicity prediction

Non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most frequently used pharmaceuticals in animals. In the current study, the biotransformation of five NSAIDs by pig liver microsomes (PLMs) was studied. The pseudo-first-order kinetics mode was obtained for the metabolization of the studied NSAIDs by PLMs in vitro. The metabolites were identified by high performance liquid chromatography with a high-resolution LTQ-Orbitrap mass spectrometry. The hydroxylation of benzene was confirmed to be the dominating metabolic pathway. Finally, the toxicity of the metabolites was predicted by the Estimation Programs Interface Suite software based on quantitative structure-activity relationships. Decreased toxicity was expected for the most metabolites of the studied NSAIDs except flurbiprofen, whose main metabolite exhibited slightly more toxicity. The present study provided a preliminary foundation to understand the metabolites of some NSAIDs and their toxicity, which was of great significance in animal food safety.

Studying Protein-Protein Interactions by Biotin AP-Tagged Pulldown and LTQ-Orbitrap Mass Spectrometry.

The study of protein-protein interactions represents a key aspect of biological research. Identifying unknown protein binding partners using mass spectrometry (MS)-based proteomics has evolved into an indispensable strategy in drug discovery. The classic approach of immunoprecipitation with specific antibodies against the proteins of interest has limitations, such as the need for immunoprecipitation-qualified antibody. The biotin AP-tag pull-down system has the advantage of high specificity, ease of use, and no requirement for antibody. It is based on the high specificity, high affinity interaction between biotin and streptavidin. After pulldown, in-gel tryptic digestion and tandem mass spectrometry (MS/MS) analysis of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) protein bands can be performed. In this work, we provide protocols that can be used for the identification of proteins that interact with FOXM1, a protein that has recently emerged as a potential biomarker and drug target in oncotherapy, as an example. We focus on the pull-down procedure and assess the efficacy of the pulldown with known FOXM1 interactors such as β-catenin. We use a high performance LTQ Orbitrap MSn system that combines rapid LTQ ion trap data acquisition with high mass accuracy Orbitrap analysis to identify the interacting proteins.