Bio: Xiaozhe Zhang is an academic researcher from Dalian Institute of Chemical Physics. The author has contributed to research in topics: Mass spectrometry & Neuropeptide. The author has an hindex of 16, co-authored 54 publications receiving 764 citations. Previous affiliations of Xiaozhe Zhang include Max Planck Society & University of Fribourg.
Papers published on a yearly basis
TL;DR: It is concluded that HILIC/MS/MS combined with the push-pull sampling method represents a sensitive technique for simultaneous monitoring of neurotransmitters from EBF samples.
Abstract: A diverse array of neurotransmitters and neuromodulators control and affect brain function A profound understanding of the signaling pathways and the neural circuits underlying behavior is therefore likely to require the tracking of concentration changes of active neurochemicals In the present study, we demonstrate the feasibility of a method allowing the simultaneous determination of the concentrations of six neurotransmitters: acetylcholine, serotonin, dopamine, gamma-aminobutyric acid (GABA), glutamate and aspartate, in the extracellular brain fluid (EBF) We used hydrophilic interaction chromatography (HILIC) coupled to tandem mass spectrometry (MS/MS) to analyze the EBF from the monkey brain A push-pull sampling method was used to collect EBF from the prefrontal cortex (PFC) of conscious monkeys at flow rates in the range of low nL/min The detection limits of acetylcholine, serotonin, dopamine, GABA, glutamate and aspartate were 0015,015,03,12, 6 and 15 femtomoles, respectively, allowing us to quantitatively determine the concentrations of these six neurotransmitters simultaneously from 500 nL in vivo samples We conclude that HILIC/MS/MS combined with the push-pull sampling method represents a sensitive technique for simultaneous monitoring of neurotransmitters from EBF samples Copyright (C) 2007 John Wiley & Sons, Ltd
TL;DR: Blood plasma samples from PD patients were collected and an LC-MS based metabolomics approach was used to identify 17 metabolites with significantly altered levels, mainly related to lipid metabolism and mitochondrial function.
Abstract: The plasma of Parkinson's disease (PD) patients may contain various altered metabolites associated with the risk or progression of the disease. Characterization of the abnormal metabolic pattern in PD plasma is therefore critical for the search for potential PD biomarkers. We collected blood plasma samples from PD patients and used an LC-MS based metabolomics approach to identify 17 metabolites with significantly altered levels. Metabolic network analysis was performed to place the metabolites linked to different pathways. The metabolic pathways involved were associated with tyrosine biosynthesis, glycerol phospholipid metabolism, carnitine metabolism and bile acid biosynthesis, within which carnitine and bile acid metabolites as potential biomarkers are first time reported. These abnormal metabolic changes in the plasma of patients with PD were mainly related to lipid metabolism and mitochondrial function.
TL;DR: Using the HPLC-APCI/MS method, 35 ginsenosides were identified in Panax ginseng and can provide more explicit information than ESI/MS for identifying and distinguishing ginsene groups.
Abstract: A new HPLC-APCI/MS method for the identification of ginsenosides has been developed. The analyses were performed on a reversed-phase C18 column using a binary eluent (acetonitrile and water) under gradient conditions. Although APCI is a high-temperature evaporative process, HPLC-APCI/MS could effectively identify thermo-labile ginsenosides. The [M-H]- ions and the thermal degradation ions of ginsenosides could be clearly observed under negative and positive ion conditions, respectively, and these were used to identify the molecular masses, the aglycone structures and the sugar groups of ginsenosides. APCI/MS can provide more explicit information than ESI/MS for identifying and distinguishing ginsenosides. Using the HPLC-APCI/MS method, 35 ginsenosides were identified in Panax ginseng.
TL;DR: The applicability of on-line coupling of reversed-phase high-performance liquid chromatography to atmospheric pressure ionization tandem mass spectrometry for the separation and characterization of hop acids mixture from the crude extract of Humulus lupulus was investigated.
Abstract: The applicability of on-line coupling of reversed-phase high-performance liquid chromatography to atmospheric pressure ionization tandem mass spectrometry for the separation and characterization of hop acids mixture from the crude extract of Humulus lupulus was investigated. The solvent system consisting of acetonitrile-aqueous formic acid was used to give proper separation of the six main hop bitter acids within 30 min. Further structural information about the components was acquired by collision-induced dissociation (CID). On the basis of analyses of the fragmentation patterns of the major α- and β-bitter acids respectively, identification of the minor ones was performed using selected reaction monitoring (SRM) with a group of qualitatively relevant selected precursor-product ion transitions for each bitter acid in a single high performance liquid chromatography (HPLC) run. Using this technique, six minor hop acids, including “adprelupulone” observed for the first time in natural resources, were detected along with the six major acids. This hyphenated techniques provides potency for rapid qualitative determination of analogs and homologs in mixtures.
TL;DR: From seeds of Strychnos nux-vomica three iridoids were isolated together with two known iridoid glucosides, loganic acid and 7-O-acetylloganic acid, establishing the structures of the compounds.
Abstract: From seeds of Strychnos nux-vomica three iridoids, 6'-O-acetylloganic acid, 4'-O-acetylloganic acid and 3'-O-acetylloganic acid were isolated together with two known iridoid glucosides, loganic acid and 7-O-acetylloganic acid. The structures of the compounds were established by ESI-MS and by 1D and 2D NMR spectroscopic methods.
01 May 2005
TL;DR: This article aims at providing an integration of brain energy metabolism across resolution scales with decisive insights into the understanding of the cellular and molecular bases of the coupling between neuronal activity and energy metabolism.
Abstract: The energy demands of the brain are high: they account for at least 20% of the body's energy consumption. Evolutionary studies indicate that the emergence of higher cognitive functions in humans is associated with an increased glucose utilization and expression of energy metabolism genes. Functional brain imaging techniques such as fMRI and PET, which are widely used in human neuroscience studies, detect signals that monitor energy delivery and use in register with neuronal activity. Recent technological advances in metabolic studies with cellular resolution have afforded decisive insights into the understanding of the cellular and molecular bases of the coupling between neuronal activity and energy metabolism and point at a key role of neuron-astrocyte metabolic interactions. This article reviews some of the most salient features emerging from recent studies and aims at providing an integration of brain energy metabolism across resolution scales.
TL;DR: Analytical techniques for the analysis of ginsenosides that are described in this chapter are thin-layer chromatography, high-performance liquid chromatography combined with various detectors, gas chromatography), colorimetry, enzyme immunoassays (EIA), capillary electrophoresis (CE), nuclear magnetic resonance (NMR) spectroscopy, and spectrophotometric methods.
Abstract: Ginsenosides are a special group of triterpenoid saponins that can be classified into two groups by the skeleton of their aglycones, namely dammarane‐ and oleanane‐type. Ginsenosides are found nearly exclusively in Panax species (ginseng) and up to now more than 150 naturally occurring ginsenosides have been isolated from roots, leaves/stems, fruits, and/or flower heads of ginseng. Ginsenosides have been the target of a lot of research as they are believed to be the main active principles behind the claims of ginsengs efficacy. The potential health effects of ginsenosides that are discussed in this chapter include anticarcinogenic, immunomodulatory, anti‐inflammatory, antiallergic, antiatherosclerotic, antihypertensive, and antidiabetic effects as well as antistress activity and effects on the central nervous system. Ginsensoides can be metabolized in the stomach (acid hydrolysis) and in the gastrointestinal tract (bacterial hydrolysis) or transformed to other ginsenosides by drying and steaming of ginseng to more bioavailable and bioactive ginsenosides. The metabolization and transformation of intact ginsenosides, which seems to play an important role for their potential health effects, are discussed. Qualitative and quantitative analytical techniques for the analysis of ginsenosides are important in relation to quality control of ginseng products and plant material and for the determination of the effects of processing of plant material as well as for the determination of the metabolism and bioavailability of ginsenosides. Analytical techniques for the analysis of ginsenosides that are described in this chapter are thin‐layer chromatography (TLC), high‐performance liquid chromatography (HPLC) combined with various detectors, gas chromatography (GC), colorimetry, enzyme immunoassays (EIA), capillary electrophoresis (CE), nuclear magnetic resonance (NMR) spectroscopy, and spectrophotometric methods.
TL;DR: The review presents an overview of studies concerning the effect of eluent composition on the ionization efficiency of ESI, APCI and APPI in LC-MS, and solvent characteristics are discussed in the light of ionization theories.
Abstract: The most widely used ionization techniques in liquid chromatography-mass spectrometry (LC-MS) are electrospray ionization (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI). All three provide user friendly coupling of LC to MS. Achieving optimal LC-MS conditions is not always easy, however, owing to the complexity of ionization processes and the many parameters affecting mass spectrometric sensitivity and chromatographic performance. The selection of eluent composition requires particular attention since a solvent that is optimal for analyte ionization often does not provide acceptable retention and resolution in LC. Compromises must then be made between ionization and chromatographic separation efficiencies. The review presents an overview of studies concerning the effect of eluent composition on the ionization efficiency of ESI, APCI and APPI in LC-MS. Solvent characteristics are discussed in the light of ionization theories, and selected analytical applications are described. The aim is to provide practical background information for the development and optimization of LC-MS methods.
01 Jan 2008