Determination of mushroom toxins ibotenic acid, muscimol and muscarine by capillary electrophoresis coupled with electrospray tandem mass spectrometry

Application to several suspected poisoning cases of a validated analytical method for the determination of muscarine in human biological matrices using liquid chromatography with high-resolution mass spectrometry detection

Despite prevention efforts, many cases of mushroom poisoning are reported around the world every year. Among the different toxins implicated in these poisonings, muscarine may induce parasympathetic neurological damage. Muscarine poisonings are poorly reported in the current literature, implying a lack of available data on muscarine concentrations in human matrices. A validated liquid chromatography with high-resolution mass spectrometry detection (Orbitrap technology) method was developed to determine muscarine concentrations in human urine, plasma, and whole blood samples. Muscarine was determined using 100 μL of biological fluids, and precipitation was used for sample preparation. Liquid chromatography-mass spectrometry was performed using an Accucore Phenyl-X analytical column with the electrospray source in positive ion mode. Muscarine was quantitated in parallel reaction monitoring (PRM) mode with D9-muscarine as the internal standard. The method was validated successfully over the concentration range 0.1-100 μg/L for plasma and whole blood and 1-100 μg/L for urine, with acceptable precision and accuracy (<13.5%), including the lower limit of quantification. Ten real cases of suspected muscarine poisoning were successfully confirmed with this validated method. Muscarine concentrations in these cases ranged from 0.12 to 14 μg/L in whole blood, Collapse

Key Words

• blood
• high‐resolution mass spectrometry
• muscarine
• poisoning
• urine

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MESH Headings

• Humans
• Muscarine/analysis
• Tandem Mass Spectrometry/methods
• Chromatography, Liquid/methods
• Mushroom Poisoning/diagnosis
• Mushroom Poisoning/urine
• Body Fluids/chemistry
• Chromatography, High Pressure Liquid/methods

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Affiliation(s)

Estelle Flament Laboratory LAT LUMTOX, La Voulte sur Rhône, France
Jean-Michel Gaulier CHU Lille, Laboratory of toxicology, Lille, France
Nathalie Paret Poison Control Centre of Lyon, SHUPT, Hospices Civils de Lyon, Lyon, France
Nathalie Jarrier Poison Control Centre of Lyon, SHUPT, Hospices Civils de Lyon, Lyon, France
Chloé Bruneau Poison Control Centre of Angers, CHU, Angers, France
Gaelle Creusat Poison Control Centre of Nancy, University Hospital, Nancy, France
Jérôme Guitton CHU Lyon, Medical unity Pharmacology-Pharmacogenetic-Toxicology, Pierre Bénite, France Faculty of Pharmacy Lyon, Toxicology Laboratory, Lyon, France
Yvan Gaillard Laboratory LAT LUMTOX, La Voulte sur Rhône, France

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Intramolecular interactions and the neutral loss of ammonia from collisionally activated, protonated ω-aminoalkyl-3-hydroxyfurazans

Gas phase fragmentation reactions of monoprotonated 4-(3-aminopropyl)- and 4-(4-aminobutyl)-3-hydroxyfurazan were investigated to examine potential interactions between functional groups. The two heterocyclic alkyl amines were ionized by electrospray ionization (ESI, positive mode) and fragmented using tandem mass spectrometry (MS/MS). The fragmentation pathways were characterized using pseudo MS3 experiments, precursor-ion scans, and density functional computations. For both heterocyclic ions, loss of ammonia was the only fragmentation process observed at low collision energies. Computational analysis indicated that the most feasible mechanism was intramolecular nucleophilic displacement of ammonia from the protonated ω-aminoalkyl side chain by N5 of the furazan ring. The alkylated nitrogen in the resulting bicyclic product ion facilitated N-O bond cleavage; subsequent neutral losses of nitric oxide (NO) and carbon monoxide (CO) occurred by homolytic bond cleavages. Next in the multistep sequence, neutral loss of ethylene from a radical cation was observed. A less favorable, competing fragmentation pathway of protonated 4-(3-aminopropyl)-3-hydroxyfurazan was consistent with cleavage of the 3-hydroxyfurazan ring and losses of NO and CO. Overall, the similar fragmentation behavior found for protonated 4-(3-aminopropyl)- and 4-(4-aminobutyl)-3-hydroxyfurazan differed from that previously characterized for furazan analogs with shorter alkyl chains. These observations demonstrate that a small change in the structure of multifunctional, heterocyclic alkyl amines may significantly influence interactions between distinct functional groups and the nature of the fragmentation process.

Five new species of Inosperma from China: Morphological characteristics, phylogenetic analyses, and toxin detection

Many species of Inosperma cause neurotoxic poisoning in humans after consumption around the world. However, the toxic species of Inosperma and its toxin content remain unclear. In the present study, we proposed five new Inosperma species from China, namely, I. longisporum, I. nivalellum, I. sphaerobulbosum, I. squamulosobrunneum, and I. squamulosohinnuleum. Morphological and molecular phylogenetic analyses based on three genes (ITS, nrLSU, rpb2) revealed that these taxa are independent species. A key to 17 species of Inosperma in China is provided. In addition, targeted screening for the most notorious mushroom neurotoxins, muscarine, psilocybin, ibotenic acid, and muscimol, in these five new species was performed by using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Our results show that the neurotoxin contents in these five species varied: I. sphaerobulbosum contains none of the tested neurotoxins; I. nivalellum is muscarine positive; I. longisporum and I. squamulosohinnuleum contain both ibotenic acid and muscimol, and I. squamulosobrunneum only contains muscimol; psilocybin was not detected in these five new species.

Further development of a liquid chromatography-high-resolution mass spectrometry/mass spectrometry-based strategy for analyzing eight biomarkers in human urine indicating toxic mushroom or Ricinus communis ingestions

Recently, we presented a strategy for analysis of eight biomarkers in human urine to verify toxic mushroom or Ricinus communis ingestions. However, screening for the full panel is not always necessary. Thus, we aimed to develop a strategy to reduce analysis time and by focusing on two sets of analytes. One set (A) for biomarkers of late-onset syndromes, such as phalloides syndrome or the syndrome after castor bean intake. Another set (B) for biomarkers of early-onset syndromes, such as pantherine-muscaria syndrome and muscarine syndrome. Both analyses should be based on hydrophilic-interaction liquid chromatography coupled with high-resolution mass spectrometry (MS)/MS (HILIC-HRMS/MS). For A, urine samples were prepared by liquid-liquid extraction using dichloromethane and subsequent solid-phase extraction of the aqueous supernatant. For B urine was precipitated using acetonitrile. Method A was validated for ricinine and α- and β-amanitin and method B for muscarine, muscimol, and ibotenic acid according to the specifications for qualitative analytical methods. In addition, robustness of recovery and normalized matrix factors to matrix variability measured by urinary creatinine was tested. Moreover, applicability was tested using 10 urine samples from patients after suspected mushroom intoxication. The analytes α- and β-amanitin, muscarine, muscimol, and ibotenic acid could be successfully identified. Finally, psilocin-O-glucuronide could be identified in two samples and unambiguously distinguished from bufotenine-O-glucuronide via their MS² patterns. In summary, the current workflow offers several advantages towards the previous method, particularly being more labor-, time-, and cost-efficient, more robust, and more sensitive.

Human Poisoning from Poisonous Higher Fungi: Focus on Analytical Toxicology and Case Reports in Forensic Toxicology

Several families of higher fungi contain mycotoxins that cause serious or even fatal poisoning when consumed by humans. The aim of this review is to inventory, from an analytical point of view, poisoning cases linked with certain significantly toxic mycotoxins: orellanine, α- and β-amanitin, muscarine, ibotenic acid and muscimol, and gyromitrin. Clinicians are calling for the cases to be documented by toxicological analysis. This document is therefore a review of poisoning cases involving these mycotoxins reported in the literature and carries out an inventory of the analytical techniques available for their identification and quantification. It seems indeed that these poisonings are only rarely documented by toxicological analysis, due mainly to a lack of analytical methods in biological matrices. There are many reasons for this issue: the numerous varieties of mushroom involved, mycotoxins with different chemical structures, a lack of knowledge about distribution and metabolism. To sum up, we are faced with (i) obstacles to the documentation and interpretation of fatal (or non-fatal) poisoning cases and (ii) a real need for analytical methods of identifying and quantifying these mycotoxins (and their metabolites) in biological matrices.

Determination of 8 Endogenous Alkaloid Components inBoletusUsing Ultrahigh-Performance Liquid Chromatography Combined with Quadrupole-Time of Flight Mass Spectrometry

A ultrahigh performance liquid chromatography coupled with quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS) method was developed for simultaneous determination of 8 endogenous alkaloid compounds inBoletus.Boletussamples were extracted by 50% (V/V) methanol-water solution, then separated by CORTECS UPLC HILIC column using a binary solvent system by gradient elution. The analytes were determined by Q-TOF/MS in TOF MS and information dependent acquisition (IDA)-MS/MS mode. The results showed that mass accuracy error of the 8 endogenous alkaloids were lower than 5.0 × 10−6, good linear relationship was got in range of 0.2–500 μg/L, and correlation coefficient was higher than 0.9990. The limit of detection was in the range of 0.002–0.100 mg/kg and the limit of quantification was in the range of 0.004–0.200 mg/kg. Recovery of the method was in range of 80.1%–101.5% with spike levels of 0.004–2.00 mg/kg, relative standard deviations were lower than 10%. The method was simple, specific, and reliable. It could be used for the rapid screening and quantitative analysis of 8 endogenous alkaloids inBoletus.

Direct Analysis of Psilocin and Muscimol in Urine Samples Using Single Drop Microextraction Technique In-Line with Capillary Electrophoresis

The fully automated system of single drop microextraction coupled with capillary electrophoresis (SDME-CE) was developed for in-line preconcentration and determination of muscimol (MUS) and psilocin (PSC) from urine samples. Those two analytes are characteristic active metabolites of Amanita and Psilocybe mushrooms, evoking visual and auditory hallucinations. Study analytes were selectively extracted from the donor phase (urine samples, pH 4) into the organic phase (a drop of octanol layer), and re-extracted to the acidic acceptor (background electrolyte, BGE), consisting of 25 mM phosphate buffer (pH 3). The optimized conditions for the extraction procedure of a 200 µL urine sample allowed us to obtain more than a 170-fold enrichment effect. The calibration curves were linear in the range of 0.05–50 mg L⁻¹, with the correlation coefficients from 0.9911 to 0.9992. The limit of detections was determined by spiking blank urine samples with appropriate standards, i.e., 0.004 mg L⁻¹ for PSC and 0.016 mg L⁻¹ for MUS, respectively. The limits of quantification varied from 0.014 mg L⁻¹ for PSC and 0.045 mg L⁻¹ for MUS. The developed method practically eliminated the sample clean-up step, which was limited only to simple dilution (1:1, v/v) and pH adjustment.

Muscarine, imidazole, oxazole and thiazole alkaloids

Covering: July 2012 to June 2015. Previous review: Nat. Prod. Rep., 2013, 30, 869-915The structurally diverse imidazole-, oxazole-, and thiazole-containing secondary metabolites are widely distributed in terrestrial and marine environments, and exhibit extensive pharmacological activities. In this review the latest progress involving the isolation, biological activities, and chemical and biogenetic synthesis studies on these natural products has been summarized.

Multivariate optimization of the hollow fibre liquid phase microextraction of muscimol in human urine samples

A liquid phase microextraction based on hollow fibre followed by liquid chromatographic determination was developed for the extraction and quantitation of the hallucinogenic muscimol from urine samples. Method applicability on polar hallucinogens was also tested on two alkaloids, a psychedelic hallucinogen, tryptamine and a polar amino acid, tryptophan which exists in its charged state in the entire pH range. A multivariate design of experiments was used in which a half fractional factorial approach was applied to screen six factors (donor phase pH, acceptor phase HCl concentration, carrier composition, stirring rate, extraction time and salt content) for their extent of vitality in carrier mediated liquid microextractions. Four factors were deemed essential for the effective extraction of each analyte. The vital factors were further optimized for the extraction of single-spiked analyte solutions using a central composite design. When the simultaneous extraction of analytes was performed under universal factor conditions biased towards maximizing the enrichment of muscimol, a good composite desirability value of 0.687 was obtained. The method was finally applied on spiked urine samples with acceptable enrichments of 4.1, 19.7 and 24.1 obtained for muscimol, tryptophan and tryptamine respectively. Matrix-based calibration curves were used to address matrix effects. The r(2) values of the matrix-based linear regression prediction models ranged from 0.9933 to 0.9986. The linearity of the regression line of the matrix-based calibration curves for each analyte was directly linked to the analyte enrichment repeatability which ranged from an RSD value of 8.3-13.1%. Limits of detection for the developed method were 5.12, 3.10 and 0.21ngmL(-1) for muscimol, tryptophan and tryptamine respectively. The developed method has proven to offer a viable alternative for the quantitation of muscimol in human urine samples.

Enzyme-luminescence method: Tool for real-time monitoring of natural neurotoxins in vitro and l-glutamate release from primary cortical neurons

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We describe the applicability of our previously developed novel enzyme-luminescence method for rapid and sensitive detection of natural neurotoxins (e.g., shellfish and mushroom toxins) using brain model cells (C6 glioma cells) in vitro.

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A racemic mixtures of the gonyautoxins (GTX), including GTX2,3 and GTX1,4 were used for evaluating the inhibition effects of these toxins on glutamate release from the C6 glioma cells. The potency was compared based on IC₅₀ values.

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The activation effect of ibotenic acid (a mushroom toxin) on glutamate release from C6 cells was also evaluated. The potency was compared based on EC₅₀ values.

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We also tested the applicability of our system for real-time detection of glutamate release from primary rat cortical neurons instead of model cells.

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This novel detection technique may be also applicable in determining neuronal differentiation ratio as well finding glutamatergic neurons without immunostaining in situ.

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This sensing tool may also has a great potential for the investigation of the effects of various growth factors and chemicals on neuronal differentiation, neurotransmitter dynamics, neurodegeneration, and synaptogenesis.

Novel enzyme-luminescence method is used for the rapid and sensitive in vitro detection of natural neurotoxins (e.g., shellfish and mushroom toxins) using model brain cells. Paralytic shellfish poisons gonyautoxins (e.g., GTX2,3 and GTX1,4) were detected at 1 nM level by their inhibition of glutamate release from C6 glioma cells upon drug stimulation (IC₅₀: GTX2,3 = 30 nM and GTX1,4 = 8 nM). Activation of glutamate release from C6 cells by ibotenic acid (a mushroom toxin) was also evaluated (EC₅₀ = 10 nM). The method was tested for real-time detection of glutamate release from primary rat cortical neurons. Dose-dependent effects of KCl (0–200 mM) and NMDA on glutamate release from primary cortical neurons were studied. The effects of different culture conditions on K⁺-depolarization-induced glutamate release were also investigated. The method may be applicable to screening of drugs and toxins, and finding glutamatergic neurons in brain slices without in situ staining.

Theoretical and experimental NMR studies on muscimol from fly agaric mushroom (Amanita muscaria)

In this article we report results of combined theoretical and experimental NMR studies on muscimol, the bioactive alkaloid from fly agaric mushroom (Amanita muscaria). The assignment of (1)H and (13)C NMR spectra of muscimol in DMSO-d6 was supported by additional two-dimensional heteronuclear correlated spectra (2D NMR) and gauge independent atomic orbital (GIAO) NMR calculations using density functional theory (DFT). The effect of solvent in theoretical calculations was included via polarized continuum model (PCM) and the hybrid three-parameter B3LYP density functional in combination with 6-311++G(3df,2pd) basis set enabled calculation of reliable structures of non-ionized (neutral) molecule and its NH and zwitterionic forms in the gas phase, chloroform, DMSO and water. GIAO NMR calculations, using equilibrium and rovibrationally averaged geometry, at B3LYP/6-31G* and B3LYP/aug-cc-pVTZ-J levels of theory provided muscimol nuclear magnetic shieldings. The theoretical proton and carbon chemical shifts were critically compared with experimental NMR spectra measured in DMSO. Our results provide useful information on its structure in solution. We believe that such data could improve the understanding of basic features of muscimol at atomistic level and provide another tool in studies related to GABA analogs.