Abstract We report a multielemental and quantitative speciation analysis study with chromatographic inductively coupled plasma–mass spectrometry (ICP–MS/MS) detection involving four elements (sulfur, selenium, arsenic, and phosphorus) in Asparagus officinalis. The samples were locally purchased and labeled to originate from different regions in two continents. Major compounds were identified and quantified with confirmation based on chemical synthesis in pure form. Nontargeted analysis revealed significant quantitative and qualitative variation for the elemental metabolomes among samples, particularly sulfur and arsenic. Sharp contrast was observed in the diversity of the profiles between sulfur and selenium, providing insight into metabolism selectivity in Asparagus. Inorganic and methylated arsenic were both detected, but their ratios showed wide variation between samples. The present work shows the potential of multielemental speciation analysis with ICP–MS/MS as a novel dimension for food characterization based on studying heteroatom-tagged metabolome.

We report a large-scale study investigating the arsenometabolome in 93 various wild mushroom species collected from natural environments. Arsenocarnitine was discovered as a novel arsenic compound previously unreported in nature and an analogue of carnitine which is a key amino acid that plays a central role in all domains of life. Identification was based on a combination of element-selective and molecular mass spectrometry and unambiguously validated by chemical synthesis. Arsenocarnitine was found to be ubiquitous with concentrations up to 147 µg As kg⁻¹ and its abundance showed a significant positive correlation with carnitine. Two highly distinct types of the mushroom species in terms of arsenic biotransformation patterns were observed, type (-) characterized by dominance of methylated anionic arsenic, and type (+) characterized by an astonishingly complex arsenometabolome tagged with the quaternary arsonium functional group. Arsenocarnitine was clearly associated with type (+) mushrooms and largely undetectable in type (-) mushrooms. The discovery of arsenocarnitine expands the narrow chemical space of natural organoarsenic compounds beyond conventional structures and provides new insights into the close relationship between arsenic and nitrogen. The distinct types of arsenometabolomes suggest variable fate of arsenic in our environment which has been underrecognized.

Abstract Understanding acetylene coordination to group VI metals is crucial for elucidating the long-standing mechanistic ambiguities of tungstoenzyme acetylene hydratase (AH), for which several contrasting pathways have been proposed. Motivated by a recently hypothesized mechanism (Biochemistry2025, 64, 10, 2154–2172.) involving one-electron oxidation of the tungsten center, we explore the reactivity of the acetylene ligand in Mo– and W–AH models bearing 4,6-dimethylpyrimidine-2-thiolate (PymS) ligands, chosen to mimic the sulfur-rich environment of the AH active site. To trigger the redox chemistry and provide protons, half an equivalent of trimethylamine-N-oxide dihydrate (TMAO·2H2O) was added to the [MoO(C2H2)(PymS)2], yielding two distinct vinylated products: 4,6-dimethyl-1-vinylpyrimidine-2(1H)-thione and 4,6-dimethyl-2-(vinylthio)pyrimidine, which could be interpreted as acetaldehyde surrogates. In this transformation, TMAO serves as an oxygen atom donor, accepting electrons from Mo(IV), and triggers the formation of the μ-oxido Mo(V) dimer, which destabilizes the coordinated C2H2 and promotes the reaction with the neighboring ligand. The presence of a Mo(V) species was detected by EPR spectroscopy, supporting a radical nature of the reaction. In contrast, the C2H2 ligand in the tungsten analogue does not undergo vinylation, likely due to its ligand environment not stabilizing the +V oxidation state. These observations may be extended to the biochemistry of the AH active site, where the W(V) oxidation state would be more readily accessible. Finally, our data provide experimental evidence for potential redox events during biological acetylene hydration and additionally suggest that acetylene coordination is essential to the process.

Allyl methyl sulfide (AMS) is an odorous and bioactive major metabolite produced following Allium food consumption and is regarded as the culprit behind the "garlic breath". Indoleethylamine N-methyltransferase (INMT) can methylate a variety of thioethers to their respective sulfonium ions in humans, aiding in their urinary excretion. We hypothesize that AMS may serve as a novel target for INMT and be metabolized to the allyl dimethyl sulfonium (ADMS) ion, which would constitute a previously undescribed pathway for metabolism of Allium food. ADMS was synthesized, and analytical methods were developed to explore its existence and characterize its levels in humans. ADMS was indeed consistently detected in all volunteers over 6 weeks without dietary intervention and found to strongly respond to controlled garlic supplementation. Striking interindividual variability in urinary ADMS was observed and found to mirror other products of INMT, which is attributable to genetic variation. ADMS is a novel metabolite in humans, and its remarkably variable production suggests variable response in body odors and health effects of Allium food and can be used to assess Allium consumption in the general human population in future epidemiological studies. More products of INMT that can serve as biomarkers of sulfur-rich food intake await discovery.

The edible and medicinal mushroom Sparassis crispa contains a diverse profile of arsenic species. We investigated the arsenic profile of extracts from four different fruiting bodies of S. crispa originating from Austria and Czechia. Besides the previously known arsenic species arsenocholine, trimethylarsine oxide, trimethyl(2-carboxyethyl)arsonium, arsenobetaine amide, and the tetramethylarsonium ion, we were able to identify the uncommon α-glycerophosphorylarsenocholine—previously only identified as a minor arsenic species in marine animals—as a major arsenic species. Furthermore, a novel arsenic compound, i.e., β-methyl arsenocholine, was identified as a naturally occurring compound in all investigated samples of S. crispa. We present methods for the preparation of synthetic α-glycerophosphorylarsenocholine and β-methyl arsenocholine, which were used to confirm their presence in S. crispa.

Bioinspired tungsten acetylene complexes containing pyridine-2-selenolato (PySe) or 6-methyl-pyridine-2-selenolato (6-MePySe) ligands were synthesized. Se-77 NMR spectroscopy allowed for an assessment of the resonance structures in the pyridine-2-selenolato ligands and the rationalization of chemoselectivity observed in regard to 1,2 migratory insertion of HC equivalent to CH. [W(CO)(C2H2)(CHCH-PySe)(PySe)] is formed exclusively via insertion of HC equivalent to CH into the W-N bond, while the use of bulkier 6-MePySe allows for the isolation of [W(CO)(C2H2)(6-MePySe)(2)], which only partially reacts with excess HC equivalent to CH to give [W(CO)(C2H2)(CHCH-6-MePySe)(6-MePySe)]. Oxidation of [W(CO)(C2H2)(6-MePySe)(2)] with pyridine-N-oxide gave the tungsten(IV) complex [WO(C2H2)(6-MePySe)(2)]. Complexes [W(CO)(C2H2)(6-MePySe)(2)] and [WO(C2H2)(6-MePySe)(2)] react with trimethyl phosphine to carbyne complex [W(CO)(CCH2PMe3)(PMe3)(2)(6-MePySe)]Cl and alkylidene complex [WO(CHCHPMe3)(PMe3)(2)(6-MePySe)]Cl, respectively. The addition of substituted alkynes to [W(CO)(3)(PySe)(2)] via thermal decarbonylation gave complexes [W(CO)(MeC equivalent to CMe)(PySe)(2)] and [W(CO)(HC equivalent to Ct-Bu)(PySe)(2)], respectively. The here presented complexes are relevant for the modeling of the active site of acetylene hydratase from Pelobacter acetylenicus, in which a tungsten atom is enclosed in a sulfur-rich coordination sphere. A recently published theoretical study concluded that the exchange of sulfur for selenium would increase the activity of the enzyme. Our findings contrast this claim as comparative analysis concludes negligible structural and electronic differences between the selenium-based and previously published sulfur-based complexes.

The total arsenic mass fraction as well as the arsenic speciation were studied in four different mushroom species with inductively coupled plasma mass spectrometry and high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry, respectively. Arsenic mass fractions detected in the mushrooms were covering a range from 0.3 to 22 mg As kg −1 dry mass. For the arsenic speciation, species like arsenobetaine, inorganic arsenic, or dimethylarsinic acid were found, which are commonly detected in mushrooms, but it was also proven that the recently discovered novel compound homoarsenocholine is present in Amanita muscaria and Ramaria sanguinea . Moreover, a previously unidentified arsenic species was isolated from Ramaria sanguinea and identified as trimethylarsonioacetamide, or in short: arsenobetaine amide. This new arsenical was synthesized and verified by spiking experiments to be present in all investigated mushroom samples. Arsenobetaine amide could be an important intermediate to further elucidate the biotransformation pathways of arsenic in the environment. Graphical Abstract

Hydrogen sulfide (H2S) is a toxic gas emitted through natural and anthropogenic activities. Chronic exposure to inhaled H2S at low sub-toxic levels is common among workers in oil refineries and may have important health implications. Inhaled H2S can be oxidized to thiosulfate or methylated to dimethylsulfide (DMS) which can be methylated to the novel human metabolite trimethylsulfonium (TMS) or oxidized to dimethylsulfoxide (DMSO) but the extent of methylation of inhaled H2S is currently unknown in humans. A total of 80 participants were recruited of which 40 were workers in an oil refinery in Kurdistan region, Iraq including those working in close contact with the facility area where H2S was measured at 1.5-5.0 mg m(-3), and 40 controls living in a nearby city with no detectable H2S or perceptible odor (<0.1 mg m(-3)). A total of 240 urine samples were measured for multiple H2S-related metabolites. DMSO was consistently found in all urine samples with concentrations generally within the range of 1.0-10 M. Although these concentrations were 10-100-fold higher than TMS urinary levels, clear correlation between DMSO and TMS was observed (r(s) 0.55, P < 0.0001), which supports DMS as common precursor. DMSO urinary levels were elevated in the oil refinery workers in close contact with the facilities (5.0 vs. 3.3 M, P 0.03), but TMS was unaltered (0.13 vs. 0.14 mu M, P 0.68). Overall, the results suggest that the investigated methylation metabolites are not sufficiently sensitive to low occupational exposure levels of inhaled H2S.

Inspired by the enzyme acetylene hydratase, we investigated the reactivity of acetylene with tungsten(II) pyrazole complexes. Our research revealed that the complex [WBr2(pz-NHCCH3)(CO)3] (pz = 3,5-dimethyl-pyrazolate) facilitates the stochiometric reaction between pzH and acetylene to give N-vinyl-pz. This vinyl compound readily hydrolyzes to acetaldehyde, mirroring the product of acetylene hydration in the enzymatic process. The formation of the vinyl compound likely involves a reactive intermediate complex where acetylene acts as a two-electron donor, in contrast to isolable acetylene complexes that are inert to nucleophilic attack by water. Results suggest an alternative mechanism for the enzyme, including vinylation of a neighboring amino acid by acetylene in the active site prior to hydration.

The As concentrations, along with 34 other elements, and the As speciation were investigated in wild-grown samples of the parasitic mushroom Tolypocladium ophioglossoides with inductively coupled plasma mass spectrometry (ICPMS) and high performance liquid chromatography coupled to ICPMS. The As concentrations were 0.070-3.44 mg kg(-1) dry mass. More remarkable was the As speciation, where up to 56% of the extracted As were found to be an unknown As species, which was marginally retained under anion- and also cation-exchange conditions. After testing several different chromatographic settings, the compound was finally isolated and identified as 2-(sulfoxyethyl) trimethylarsonium ion (in short: arsenocholine-O-sulfate) with high resolution mass spectrometry. The compound was synthesized and further quantified in all investigated samples via ion-pair chromatography coupled to ICPMS. In addition to the high abundance of arsenocholine-O-sulfate in T. ophioglossoides, small amounts of this As species were also detected in one sample of the host mushroom, Elaphomyces asperulus. In a sample of another parasitic mushroom, Ophiocordyceps sinensis, arsenocholine-O-sulfate could not be detected, but the main species was another unknown compound that was oxidized to inorganic As(V) with hydrogen peroxide. This is the first discovery of arsenocholine-O-sulfate in nature. It is possible that it is present in many other organisms, at least in low concentrations, and just has not been detected there yet because of its unusual chromatographic behavior. The existence of arsenocholine-O-sulfate brings up questions again about the biotransformation pathways of As in the environment and the specific behavior of fungi. (C) 2020 The Authors. Published by Elsevier Ltd.

The determination of the two isomers of amavadin and other V species in Amanita muscaria with HPLC-ICPMS.

Podophyllotoxin is probably the most prominent representative of lignan natural products. Deoxy-, epi-, and podophyllotoxin, which are all precursors to frequently used chemotherapeutic agents, were prepared by a stereodivergent biotransformation and a biocatalytic kinetic resolution of the corresponding dibenzylbutyrolactones with the same 2-oxoglutarate-dependent dioxygenase. The reaction can be conducted on 2 g scale, and the enzyme allows tailoring of the initial, "natural" structure and thus transforms various non-natural derivatives. Depending on the substitution pattern, the enzyme performs an oxidative C-C bond formation by C-H activation or hydroxylation at the benzylic position prone to ring closure.

The asymmetric allylation under the assistance of catalytic amounts of 3,3'-bis(2,4,6-triisopropylphenyl)-1,1'-binaphthyl-2,2'-diyl hydrogen phosphate (TRIP) allows the concise construction of the lignan scaffold from simple aldehydes and allylic bromides with full control of the two formed stereocenters. This young methodology has been employed to synthesize four naturally and pharmaceutically active lignans. Members of the dibenzylbutyrolactone, the tetraline, and the dibenzocyclooctadiene classes have been synthesized in 40-47% overall yield along four-step synthetic routes.

AbstractPodophyllotoxin (1) ist einer der bekanntesten Vertreter von natürlich vorkommenden Lignanen. Deoxy‐, epi‐ und Podophyllotoxin, welche alle Vorstufen für häufig verwendete chemotherapeutische Verbindungen darstellen, wurden mithilfe einer stereodivergenten Biotransformation und biokatalytischen kinetischen Racematspaltung der jeweiligen Dibenzylbutyrolactone durch dieselbe 2‐Oxoglutarat‐abhängige Dioxygenase (2‐ODD) hergestellt. Zudem konnte gezeigt werden, dass ein “Upscaling” der Reaktion auf 2 g möglich ist, sowie dass das 2‐ODD‐Enzym Modifikationen des “natürlichen” Substrates toleriert und somit verschiedenste nichtnatürliche Derivate umsetzen kann. Das Enzym führt je nach Substituentenmuster entweder eine oxidative C‐C‐Bindungsbildung durch C‐H‐Aktivierung oder Hydroxylierung an der für die Ringschließung zugänglichen benzylischen Position durch.