2021 SGMS/SMS Meeting

For the 38th meeting of the SGMS we will join forces with the Swiss Metabolomics Society (SMS). The meeting will take place at the Dorint Resort Blüemlisalp Beatenberg, 18-19 November 2021 high above Lake Thun in the Bernese Oberland, with a scenic view of the Swiss Alps! The meeting will be preceeded by the 3rd SGMS School on 16-17 November 2021.

In case that Covid-related circumstances do not allow to have an in-person meeting, we will have a full and interactive online meeting planned for you so that the meeting will take place for sure!

Registration Abstract Submission Program Abstract Booklet Plenary Lectures Short communications Poster flash talks Sponsors

Confirmed Plenary Speakers for 2021

• Pablo Sinues, University of Basel (abstract)
• Thorsten Benter, University of Wuppertal (abstract)
• Ralf Weber, University of Birmingham (abstract)
• Silke Grabherr, University of Lausanne (abstract)
• Michael Witting, Helmholtz Zentrum München (abstract)

2021 SGMS Meeting and SGMS School Registration, Deadlines & Fees

A valid COVID certificate is a prerequisite to participate at our annual on-site meeting. Due to the complex pandemic situation, there will be a registration process in two steps.

1. Pre-Registration: you must decide first whether you would like to attend an on-site or an online SGMS school and conference. The lectures will be streamed in any case. 
2. By mid-October, a decision will be made on the final format and capacity. At this point, you will receive an invoice according to the format of the conference!

Do NOT pay your meeting fees in advance. 

Number of participants limited to 100 for the meeting and 50 for the school. So far BAG and hotel rules apply.

• Deadline for registration and abstract submission has been closed. 

• Meeting fees

Abstract submission

Oral presentations: Abstract submission for a 15 minute oral presentation is no longer possible. Among the proposed contributions, we have chosen submissions of fundamental and applied research focusing on novel mass spectrometry research of any kind. 

Poster flash talks: Abstract submission for a virtual poster session with 3-minute (pre-recorded) flash talks is no longer possible. Poster presenters must follow the instructions given here (pdf). 

Meeting format

Both Meeting and School will be held in a hybrid form, meaning you can join us in Beatenberg or online. On-site participation will require a valid COVID certificate. 

All lectures and workshops for on-site participation will take place at the main lecture hall of the Dorint Hotel in Beatenberg, Switzerland (Google Maps for travel directions)

All coffee breaks, lunch(es) and dinner(s) will take place in the Dorint hotel lobby/restaurants.

School Only
Registration includes one night with breakfast at the Dorint hotel, all lectures/workshops as well as coffee breaks, lunch and dinner on Tuesday, lunch on Wednesday. Monday night accommodation and dinner on request. For students, the Monday night stay at the hotel is included.

SGMS Annual Meeting
Registration includes one night with breakfast at the Dorint hotel, Thursday lunch, Apéro and SGMS dinner, Friday lunch, and coffee breaks.

School & SGMS Annual Meeting
Registration includes three nights with breakfast at the Dorint hotel, and all of the additional items included for School and SGSM meeting registration. Monday night accommodation and dinner on request. 

Program

The whole meeting program in pdf format can be downloaded [ HERE ]

Abstract Booklet

All abstracts from the Plenary, Short Communications and Poster talks can be downloaded [ HERE ]. This is a dynamic document as we are still receiving the contributions of the Poster Talks.

Plenary lectures

Pablo Sinues: Mass Spectrometry-driven Translational Breath Research

Translational Medicine Breath Research
University of Basel

Switzerland

Exhaled breath contains valuable biochemical information at the metabolic level. Hence, it holds great potential as a non-invasive method to assist in clinical diagnosis and therapeutic. While there has been progress in making use of breath tests to guide clinical decision making, the full potential of exhaled breath analysis still remains to be exploited.  

I will present a summary of the technical developments that allowed secondary electrospray ionization-high resolution mass spectrometry to become a reference analytical platform for real-time trace gas analysis. Subsequently, I will illustrate how are we exploiting this technology in a clinical setting to address unmet clinical needs. For example, I will showcase how we use breath analysis to predict drug blood concentrations in epileptic patients, as well as risk estimates for drug therapy effects as well as side effects. Further examples of the potential of this technique include the diagnosis of infectious respiratory diseases, enabling the identification of the responsible pathogen within minutes. Ultimately, this work aims to improve diagnosis, to better phenotype complex pathophysiological processes, as well as to personalize therapy.

Thorsten Benter: Charge Retention/Charge Depletion in ESI-MS

Physical Chemistry & Theoretical Chemistry
Faculty for Mathematics and Natural Sciences
University of Wuppertal

Germany

Even today, a comprehensive and congruent model for the electrospray ionization (ESI) process explaining all experimental observations is not established. This is due to the fact that the “ESI process” does not only include the (liquid phase) ionization of a molecule but also the liquid-gas phase transfer - including fluid dynamics and interface- and electrochemistry. The formation and evolution of charged droplets, the release of ions from charged droplets, the transport of ions/droplets into the vacuum system of a mass spectrometer, ion activation, transformation (i.e., chemistry), and means of preparing a defined ion beam in the ion transfer stage all potentially impact on the observed mass spectrum.
A phenomenon coined in the literature as supercharging may yield new insights in the formation processes of multiply charged ions from ESI. Supercharging is “used” to generate highly charged ion species, which may then be subjected to selected fragmentation methods (e.g., ETD, ECD). There are two different approaches to achieve supercharging: The conventional way is adding supercharging agents (SCAs) to the sprayed analyte solution. In contrast, supercharging is also achieved by adding gas phase components (e.g. acetonitrile) into the ion source.
This presentation focuses on the systematic investigation of the impact of liquid and gas phase modifiers on the observed ion population and changes of the average charge state of the peptide Substance P (SP, sequence: RPKPQQFFGLM). SP is used as a model analyte since it is well characterized with regard to its structure and ionization behavior. In addition, proxies of individual motives of SP, e.g., 1,5-diaminopentane, ethylenediamine, n-butylamine, are also investigated with regard to chemically induced charge state changes.
Results from experimental as well as theoretical work [1,2] are presented and discussed.

[1] Thinius, M. et al.; “Charge Retention/Charge Depletion in ESI-MS – Experimental Evidence”; J. Am. Chem. Soc. Mass Spectrom. DOI: 10.1021/jasms.9b00044.
[2] Haack, A. et al.; “Charge Retention/Charge Depletion in ESI-MS – Theoretical Rationale”; J. Am. Chem. Soc. Mass Spectrom. DOI: 10.1021/jasms.9b00045.

Ralf Weber: Towards More Complete Annotation of Model Organism Metabolomes: Analytical and Computational Approaches

School of Biosciences & Phenome Centre Birmingham
University of Birmingham

United Kingdom

Our knowledge of the metabolic composition of model organisms, or even human biofluids, remains remarkably limited. Identifying the collection of metabolites that make up these matrices remains one of the greatest roadblocks to deriving biological knowledge from non-targeted metabolomics datasets. Calls for community-driven characterisation of model organism metabolomes have recently been issued to address this fundamental knowledge gap. Here we present a novel analytical and computational workflow – the Deep Metabolome Annotation (DMA) workflow – for characterising (model organism) metabolomes using extensive separation and analytical techniques, as well as an extensive set of existing and novel computational tools to achieve large-scale metabolome annotation in an untargeted manner. 

The DMA workflow takes as input a single, complex biological sample matrix, from which polar and apolar metabolites are independently extracted. Resulting extracts are each fractionated over two distinct solid-phase extraction cartridges. SPE fraction aliquots are, in turn, further fractionated using multiple, complementary liquid chromatography methods, with concurrent fraction collection and high-resolution tandem mass spectrometry (MS) analysis. Finally, resulting liquid chromatography fractions are infused into Orbitrap^TM platforms for extensive high-resolution tandem and multiple-stage MS (MSⁿ) analyses (i.e. CID and HCD-based fragmentation) of purified spectral species. The complexity of both the experimental and computational steps involved in achieving DMA necessitates careful consideration of how to manage the large volumes of data generated, as well as novel computational tools to facilitate analysis. Here we introduce a set of novel tools and a workflow for the annotation of MSⁿ data as well as a suite of web-based applications, collectively named MOGI (Metabolomics Organisation with Galaxy and ISA), to support DMA efforts. The latter provides a database and web-based platform for both managing and organising large-scale DMA data analyses, and associated results, using Galaxy-based workflows, while integrating these analyses within the ISA (Investigation, Study and Assay) framework.

We demonstrate the successful application of the DMA workflow in advancing understanding of the metabolome of Daphnia magna - a keystone species of freshwater ecosystems and NIH model organism for human health. 

Silke Grabherr: Forensic Imaging and the Role of Magnetic Resonance Spectrometry in Forensic Medicine

University Center of Legal Medicine Lausanne-Geneva

Switzerland

Forensic Imaging has become an important field in forensic medicine. In many countries, especially in Europe and in Asia it is regularly used as adjunct to conventional forensic and medico-legal investigations in order to document and examine a human body after death or to perform a non-invasive documentation of lesions on living persons (victims or perpetrators).

Different technological methods are today used to perform forensic imaging. Most of them are issues from clinical radiology, but also other techniques, such as 3D-surface scanning are part of the applied panel. Among the radiological techniques, Multi-Detector Computed Tomography (MDCT) is the most often used. It is therefore well known as Post-mortem Computed Tomography (PMCT). In order to render it more informative, it can be combined with minimally invasive approaches such as post-mortem angiography (PMCTA) or post-mortem imaging-guided sample collection. 

Magnetic Resonance Imaging (MRI) also plays in interesting role in Forensic Imaging, although its application is mostly limited to research purposes. Currently, it is only rarely applied as routing investigation. Examples of its application are the investigation of the structures of the neck for living victims that suffered an attempted strangulation and post-mortem investigations of deceased new-borns and fetuses. In these cases, it represents an alternative to a conventional autopsy that is most of the time refused by the grieving family. Main research fields in Post-mortem MRI (PMRI) are the investigation of the brain in cases of asphyxia and of cardiac tissue in cases of sudden cardiac death. 

Beside this, investigations have also been made by using Magnetic Resonance Spectrometry (MRS). The existing literature points towards two main interests: investigating the post-mortem interval (in order to estimate the time of death) and investigating the presence of foreign components within the body (research for drugs or other substances with an interest in forensic toxicology). By using proton magnetic resonance spectroscopy ((1) H MRS), it is therefore possible to detect substances such as cocaine within the examined matrices. This allows performing drug research within the body and objects of forensic interest (e.g. smuggling of dissolved drugs).On the other hand, the observation of concentration changes of metabolites, usually observed in vivo in brain tissue, and the appearance of decay products was tested in order to eventually estimate the post-mortem interval.

This presentation shall give an overview of the current role of forensic imaging worldwide and in Switzerland. A special focus is put on forensic applications of MRI and MRS. 

Michael Witting: Data Independent Acquisition – The future in Metabolomics?

Helmholtz Zentrum München

Germany

Metabolomics, the systematic study of all metabolites in a given system, has entered the center stage in basic and (bio)medical research. Ever increasing capabilities of analytical chemistry approaches, mostly Nuclear Magnetic Resonance (NMR) and Mass Spectrometry (MS), allow increased throughput, better sensitivity and broader coverage of the metabolome. MS, hyphenated with chromatographic or electrophoretic separation, offers the possibility to detect hundreds to thousands of metabolites, both known and unknown ones, in a single run.

The identification of metabolites in MS relies on the use of tandem MS and either the comparison against reference database, manual or in silico analysis of obtained spectra. Likewise, it can increase selectivity and sensitivity for quantification of metabolites. Data Dependent Acquisition of tandem MS (DDA) is the current standard technique for obtaining tandem MS data in non-targeted metabolomics selecting the n highest precursor m/z, while targeted metabolomics relies on Multiple Reaction Monitoring (MRM).

In recent years, Data Independent Acquisition (DIA) as approach between the DDA and MRM has been established to overcome the shortcomings of both. While already widespread in proteomics, DIA applications in metabolomics are now being established. We highlight the usability of DIA in metabolomics for the identification of lipids in the model organism Caenorhabditis elegans in combination with ion mobility as well as the use for quantification together with new bioinformatics solutions.

Abstracts

Short communications

High-throughput molecular identification using high-resolution ion mobility and multiplexed IR spectroscopy

Vasyl Yatsyna^1,2, Ali H. Abikhodr¹, and Thomas R. Rizzo¹

1. Laboratoire de Chimie Physique Moleculaire, École Polytechnique Federale de Lausanne, EPFL SB ISIC LCPM, Station 6, CH-1015 Lausanne, Switzerland
2. University of Gothenburg, Department of Physics, 412 96 Gothenburg, Sweden

Separation and identification of isomers is a long-standing problem in analytical chemistry, and is especially crucial in the fields of glycomics, metabolomics and lipidomics. In the recent years, infrared (IR) ion spectroscopy has shown a great promise for highly-sensitive and reliable molecular identification [1,2], especially when combined with a rapid separation technique such as ion mobility spectrometry (IMS). Nevertheless, incorporation of IR spectroscopy into analytical workflows requires high-throughput approaches for the acquisition of IR spectra that would allow to identify multiple species in a single laser scan and in a relatively short timeframe. To address this issue, we have developed a novel approach based on Hadamard transform multiplexing that allows acquiring IR fingerprint spectra of all isomeric species separated by high-resolution IMS in a single laser scan.

In this approach, we use nano-electrospray ionization to produce analyte ions, separate them by high-resolution ion mobility, and then send multiple combinations of ion packets with different mobility (i.e., size and shape) to the cryogenic ion trap for messenger-tagging spectroscopy and TOF-MS analysis. Pseudorandom sequences of length n originating from Simplex matrices S(n x n) are used to select the ions that are sent for spectroscopy, and n sequences in total are sent at each laser wavelength step. In other words, we convolute the IMS-MS data using S (n x n) matrix at each laser wavelength, whereas deconvolution of this data using inverse operation yields IR spectra of all species separated by ion mobility. Thanks to multiplexing, the IR spectra obtained in this manner have a higher signal-to-noise ratio than those obtained without multiplexing.

We demonstrate the approach by recording highly-resolved vibrational spectra of 37 peptides found in bovine serum albumin tryptic digest. The spectroscopic analysis in the NH/OH stretch frequency region was completed in 22 minutes and with a 2-fold improvement in the signal-to-noise ratio thanks to multiplexing. Moreover, we applied multiplexed spectroscopy to study isomeric mixtures of disaccharides, as well as isomeric oligosaccharide mixtures found in human milk. In conclusion, the presented approach can be easily implemented in various IMS-MS setups combined with ion trapping and laser irradiation, and is particularly promising for the analysis of complex mixtures with a broad range of ion mobilities.

References:

1. Ahmed Ben Faleh, Stephan Warnke, and Thomas R. Rizzo, Anal. Chem. 2019, 91, 7, 4876-4882.
2. Jonathan Martens, Giel Berden et al., Scientific Reports, 2017, 7, 3363.

Personalised therapeutic management of epileptic patients guided by pathway-driven breath metabolomics

Kapil Dev Singh^1,2, Martin Osswald³, Victoria C. Ziesenitz¹, Mo Awchi^1,2, Jakob Usemann¹, Lukas L. Imbach³, Malcolm Kohler³, Diego García-Gómez⁴, Johannes van den Anker¹, Urs Frey^1,2, Alexandre N. Datta¹ & Pablo Sinues^1,2

1. University Children’s Hospital Basel, University of Basel, Basel, Switzerland.
2. Department of Biomedical Engineering, University of Basel, Basel, Switzerland.
3. University Hospital Zurich, University of Zurich, Zurich, Switzerland.
4. Department of Analytical Chemistry, University of Salamanca, Salamanca, Spain.

Background: Therapeutic management of epilepsy remains a challenge, since optimal systemic antiseizure medication (ASM) concentrations do not always correlate with improved clinical outcome and minimal side effects. We tested the feasibility of noninvasive real-time breath metabolomics as an extension of traditional therapeutic drug monitoring for patient stratification by simultaneously monitoring drug-related and drug-modulated metabolites.

Methods: This proof-of-principle observational study involved 93 breath measurements of 54 paediatric patients monitored over a period of 2.5 years, along with an adult’s cohort of 37 patients measured in two different hospitals. Exhaled breath metabolome of epileptic patients was measured in real time using secondary electrospray ionisation–high-resolution mass spectrometry (SESI–HRMS).

Results: We show that systemic ASM concentrations could be predicted by the breath test. Total and free valproic acid (VPA, an ASM) is predicted with concordance correlation coefficient (CCC) of 0.63 and 0.66, respectively. We also find (i) high between- and within-subject heterogeneity in VPA metabolism; (ii) several amino acid metabolic pathways are significantly enriched (p < 0.01) in patients suffering from side effects; (iii) tyrosine metabolism is significantly enriched (p < 0.001), with downregulated pathway compounds in non-responders.

Conclusions: These results show that real-time breath analysis of epileptic patients provides reliable estimations of systemic drug concentrations along with risk estimates for drug response and side effects.

EC-TOF: Simultaneous detection of EI and CI ions for Increased Identification Probabilities in Non-Target-Analysis

Steffen Bräkling¹, Sonja Klee², Hendrik Kersten¹, Carsten Stoermer², Urs Rohner², Thorsten Benter¹

1. University of Wuppertal, Department of Physical and Theoretical Chemistry,
2. TOFWERK AG

Many non-target analysis (NTA) approaches using GC-MS are only able to identify about 50 60 % of the found unknown compounds. Often, common library searches using 70 eV electron ionization (EI) do not generate satisfactory results, due to missing molecular ion information, non-specific fragments or simply lack of compounds in the data base. To generate this molecular information the use of a softer ionization process e.g., chemical ionization (CI) in a second GC run seems to be constructive. A second GC run is very time consuming and subsequent data alignment between EI and CI data can become highly complex. 

Here we present an instrument operating an EI and a CI source simultaneously using a single TOF analyzer for detection. Both ion sources are sampling the same GC-effluent during a single chromatographic separation step. A fast ion optical switching allows for scanning each chromatographic peak with the CI and EI source generating highly reproducible and non disturbed 70 eV fragmentation spectra for structural analysis and library comparisons, simultaneous to a quasi-molecular ion spectrum used for accurate mass sum formula estimation. Information given by each ion source are always linked via the retention time due to no significant time differences between the recorded EI and CI chromatogram. To overcome classical CI source drawbacks a new medium pressure CI-Source was developed and is presented. Principle of instrumental operation will be shown using several GC-MS-standards next to recent application development measurements depicting the performance and advantage of the EC-TOF for compound identification in non-targeted and suspected screening approaches.

The Orbitrap-specific feature extraction software tool for metabolomics

S. Girel¹, K. Nagornov², A. Kozhinov², S. Rudaz¹, Y. Tsybin²

1. University of Geneva
2. Spectroswiss, 1015 Lausanne, Switzerland

Time-of-flight (ToF) mass spectrometers are often considered the gold standard for metabolomic applications due to moderate instrumentation costs, sufficient resolving power, sensitivity, isotopic abundance ratio fidelity and high throughput. Hence, the majority of open source and commercial software packages for metabolomic workflows are particularly adapted for processing of the ToF data. With the introduction of orbitraps, Fourier transform mass spectrometry (FTMS) gained a noticeable share in metabolomics thanks to its superior resolving power, sensitivity, and ease of use. FT mass spectra differ from those produced by ToF instruments in terms of method-specific artifacts, continuity, peak shape and peak width (resolution). As a result, initial attempts to investigate possible discrepancies from applying established data processing techniques in metabolomics to FTMS data were hampered by a relative absence of FTMS-specific data processing packages.

Herein, we report the implementation of a tool for targeted data extraction from untargeted FTMS datasets empowered by the advanced FTMS data processing software suite, Peak-by-Peak, which includes a recently reported FTMS Simulator (https://pubs.acs.org/doi/10.1021/jasms.0c00190). The newly developed tool first automatically extracts metadata, such as instrument model and acquisition parameters. Next, FTMS profiles for the species of interest are accurately computed, followed by extraction of selected ion chromatograms from the raw data (mass spectra or time-domain transients) by matching of thus produced in silico mass spectra with the measured profiles at the user-defined mass error.

In our hands, benchmarking of the new software against metabolomic packages capable of profile mass spectra processing with established algorithms (i.e., Progenesis QI and MS-DIAL) demonstrated comparable or superior feature extraction efficiency. On top of that, both established tools introduced minor mass measurement errors of general nature and demonstrated workflow-specific data losses. A brief discussion of those is provided, along with recommendations for the users. The described FTMS data processing tool is offered on a commercial basis, featuring a convenient graphic user interface and supports .RAW, .D (folder) and .HDF mass spectrometry data formats. The evaluation version is free and then reduced fees apply to non-profit research institutions.

MSNovelist: de novo structure elucidation from MS2 spectra

Michael A. Stravs¹, Kai Dührkop², Sebastian Böcker², Nicola Zamboni ¹

1. Institute of Molecular Systems Biology, ETH Zürich, CH-8092 Zürich, Switzerland
2. Institut für Informatik, Friedrich-Schiller-Universität Jena, D-07743 Jena, Germany

Structural elucidation of small molecules remains a key challenge in mass spectrometry and metabolomics. Current methods search spectral libraries or structure databases, but cannot predict structures for truly novel, unknown compounds. We present MSNovelist, a method for de novo structure generation from MS2 spectra. Molecular fingerprint prediction using CSI:FingerID is used as an input for structure generation with an encoder-decoder neural network. Importantly, the neural network is trained with more than million molecular fingerprints, bypassing the bottleneck of limited training data from MS2 spectra.

From 3863 spectra from the GNPS library, MSNovelist identified 24% of spectra correctly on rank 1 (compared to 39% by database search), and 61% of the spectra that were correctly identified by database search. We applied the method to a bryophyte dataset to identify potential novel metabolites. For seven features, the de novo prediction substantially outscored the best database candidate, providing evidence for likely novel structures and candidates for further validation. A feature with m/z 381.1020 was tentatively annotated as a novel polyphenol with a flavonoid core. In summary, we demonstrated de novo structure generation from MS2 spectra on a validation dataset and its application for the untargeted discovery of novel metabolites. The model is available open-source at https://github.com/meowcat/MSNovelist and as a Docker container.

Omic-scale quantitative HILIC-MS/MS approach for circulatory lipid phenotyping in clinical studies

Jessica Medina¹, Rebecca Borreggine¹, Tony Teav¹, Martin Jech², Alan Atkins², Claudia Martins², Hector Gallart-Ayala¹, Julijana Ivanisevic¹

1. Metabolomics Platform, faculty of biology and medicine, University of Lausanne
2. Thermo Fisher Scientific, San Jose, California, United States

The lipidome comprises a large set of lipid metabolites with diverse chemical properties and biological roles, including signaling molecules, cell membrane components and energy storage molecules. Due to these essential roles that lipids have in metabolism, the interest in a comprehensive characterization of the human lipidome has significantly increased. The possibility of measuring a broader lipid panel could significantly improve the accuracy of disease risk prediction and diagnosis. The acquisition of quantitative data has become a necessity in epidemiological studies to allow for cross-comparison and for the translation to clinics.

Mass spectrometry (MS) based approaches have improved the sensitivity and selectivity of lipid analysis allowing the measurement of hundreds of lipid species from minimal sample amount in a high-throughput manner. Liquid chromatography coupled to MS offers the broadest breath of coverage comprising low abundant and isobaric species.

In the present work, we have developed a high-coverage method using Hydrophilic Interaction Liquid Chromatography coupled to tandem mass spectrometry (HILIC-MS/MS) to quantify circulatory lipids. Single step plasma extraction with isopropanol (1/5 v/v) and single point calibration using 72 internal standards (IS) covering different lipid classes with diverse alkyl chain lengths and unsaturation degree were used for lipid quantification. The analysis of 857 lipid species was carried out using an Acquity BEH Amide column and a triple quadrupole instrument operating in tMRM (TSQ Altis, Thermo Scientific). Initially, the linearity assessment (r2 =0.95-0.99) was carried out using NIST plasma 1950 to determine the applicability of the single point calibration. Then, the method accuracy, precision, sensitivity and selectivity were evaluated by the quantification of NIST Plasma reference material (NIST SRM 1950, Type 1 Diabetes, High TAG, Young African-American) and cross-comparison to reported consensus values. Using the developed HILIC-MS/MS method, 543 lipid species (CE (8), CER(26), DAG (13), DCER (5), HCER (22), LCER (13), LPC (9), MAG (14), SM (31), TAG (402)) were quantified in positive and 314 lipid species ( PS (7), PI (35), PG (17), PE (86), LPI (7), CL (15), FFA (17), LPC (19), LPE (15), LPG (5), PC (91)) in negative ionization mode, in a high-throughput manner that warrants the application in clinical research studies.

Cyclic Ion Mobility Spectrometry-Mass Spectrometry to study the acyl migration of glucuronide metabolites

David Higton¹, Ian D Wilson², Johannes P C Vissers¹

1. Waters Corporation, Stamford Rd, Wilmslow, SK9 4AX, UK
2. Division of Systems Medicine, Department of Metabolism, Digestion and Reproduction, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, UK

1-β-O-acyl-glucuronides (AGs) are often major metabolites of carboxylic acid-containing drugs and other xenobiotics. Their production in-vivo can be a concern are of concern with regulators as AGs have been linked with hepatotoxicity that has resulted in drug withdrawal. The rate of transacylation of the 1-β-O-acyl form to the 2-,3- and 4-O-acyl isomers is one method to assess the potential risk posed by AGs. Whilst this transacylation can be studied using in-vitro incubation of the 1-β- form in buffer followed by LC-MS, this is time consuming and difficult for rapid transacylating species. The use of the SELECT SERIES Cyclic Ion Mobility Spectrometry-Mass Spectrometer (cIM-MS) can provide real-time monitoring of this reaction.

A machine learning based approach was used for the prediction of CCS values was used to indicate that the 1-β-O-acyl isomer had the potential to be separated from the other acyl glucuronide isomers by means of IM-MS. Initial analysis of an incubated sample where the reaction had gone to completion demonstrated that the 1-β-O-acyl form confirmed this prediction and the 1-β-O-acyl isomer could be separated from the other forms. Following this, an automated experiment using flow injection analysis was set-up to provide in process monitoring of the trans acylation experiment with samples being taken every 2 minutes. The log peak response in the arrival time distribution (ATD) for the 1-β-O-acyl isomer was plotted against incubation time to obtain the half-life of the reaction. The ATDs were compared with those obtained using LC-cIMS-MS to confirm the assignment of the different isomers.

Poster presentations

a link to the virtual poster session was sent to all meeting participants (pdf with general information)

Sponsors