Identification Of Metabolites Research Articles

Metabolomics in Pakistan: A Comprehensive Analysis of Availability, Practices, and Challenges in Clinical Laboratories.

To comprehensively analyse the current state of metabolomics in clinical laboratories across Pakistan. Cross-sectional survey. Place and Duration of the Study: Section of Chemical Pathology, Department of Pathology and Laboratory Medicine, The Aga Khan University, Karachi, Pakistan, from June to November 2022. This survey assessed metabolomics availability, computational methods, and resources in Pakistani clinical laboratories. The survey questionnaire was distributed within the chemical pathology community via Google Forms, and responses were garnered from 44 chemical pathologists across 17 laboratories in 10 cities. Among respondents, 11 had formal metabolomics training, with three having less than 1 year, five more than 1 year, and 33 lacking any experience. Primary clinical applications included inherited metabolic disorders, bio-informatics, microbiology, therapeutic drug monitoring, toxicology, and nutritional and environmental science. Thirty-three labs reported no omics-related technology; LC-MS and GC-MS were present in eight labs and capillary spectroscopy, direct infusion mass spectroscopy, and Fourier transform infrared-spectroscopy were predominantly used for metabolite identification. Challenges identified in implementing metabolomics included lack of awareness, limited expertise, low volume, restricted applicability, high instrument costs, and insufficient funding. Metabolomics in Pakistan faces limitations, but the chemical pathology community expresses strong interest, emphasising the need for intensified efforts in education and training in this emerging field. Metabolomics, Chemical pathology, Pakistan, Clinical laboratories, Genetics, Survey.

Application of a molecular networking approach using LC-HRMS combined with the MetWork webserver for clinical and forensic toxicology

Backgrounds and aimsIn toxicology, LC-HRMS for untargeted screening yields a great deal of high quality spectral data. However, there we lack tools to visualize/organize the MS data. We applied molecular networking (MN) to untargeted screening interpretation. Our aims were to compare theoretical MS libraries obtained in silico with our experimental dataset in patients to broaden its application, and to use the MetWork web application for metabolite identification. MethodsSamples were analyzed using an LC-HRMS system. For MN, data was generated using MZmine, and analyzed and visualized using MetGem. MetWork annotations were filtered and this file was used for annotation of the previously obtained MN. Results155 compounds including drugs found in patients were recorded. Using this dataset, we confirmed in 60 patients intake of tramadol, amitriptyline bromazepam, and cocaine. The results obtained by the reference methods were confirmed by MN approaches. Eighty percent of the compounds were common to both conventional and MN approaches. Using MetWork, metabolites and parent drugs such as amitriptyline, its metabolite nortriptyline and amitriptyline glucuronide phase 2 metabolites were anticipated and proposed as putative annotations. ConclusionThe workflow increases confidence in toxicological screening by highlighting putative structures in biological matrices in combination with CFM-ID (Competitive Fragmentation Modeling for Metabolite Identification) and MetWork to extend the annotation of potential drugs even without a reference standard.

Potential of high-resolution mass spectrometry for identification and structural elucidation of scopolamine metabolomic biomarkers in a confirmed case of Brugmansia intoxication. Specially application in drug-facilitated crimes

In forensic toxicology, scopolamine remains as one of the most challenging alkaloid in terms of analytical detection. Given its rapid elimination, the detection window in common matrices is short. Taking advantage of a real case of Brugmansia intoxication, a metabolic study was carried out. We report the real case of a 16-year-old boy admitted to an Emergency Unit after consumption at high school of a beverage made of Brugmansia dried flowers. The medical staff noticed agitation, mydriasis and tachycardia. Scopolamine and atropine were positively detected in biological fluids using liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS/MS). To better characterize the intake and identify metabolic biomarkers, we developed a data mining workflow specific to tropane alkaloids and applied it to the urine sample. This metabolic profile may be useful in providing analytical methods with a wider detection window particularly in drug-facilitated crimes (DFC). Scopolamine and atropine metabolites were predicted in silico with GLORYx freeware to assist in metabolite identification. The previously published metabolic pathways for scopolamine and atropine in mammals were studied as well. A total of fifteen phase I and II metabolites were tentatively identified for scopolamine, while one metabolite was detected for atropine. In addition, we identified some tropane alkaloids from the plant that were also metabolized. These metabolites can be used as biomarkers of exposure to Solanaceae plants and may also be useful to distinguish between natural product use and clinical therapy.

Identification of serum metabolites associated with polybrominated diphenyl ethers (PBDEs) exposure in papillary thyroid carcinoma: a case–control study

As the most common endocrine cancer, thyroid cancer (TC) has sharply increased globally over the past three decades. The growing incidence of TC might be counted by genetics, radiation, iodine, autoimmune disease, and exposure to environmental endocrine–disrupting chemicals (EDCs). Polybrominated diphenyl ethers (PBDEs), being typical EDCs, have been widely utilized in plastics, electronics, furniture, and textiles as flame retardants since the 1980s, and research has indicated a significant correlation between their exposure and the risk of TC. Even so, PBDEs exposure impact on the metabolic signature for TC remains unexplored. In this study, eight congeners of PBDEs were determined in serum from 111 patents with papillary thyroid cancer (PTC) and 111 healthy participants based on case–control epidemiology using gas chromatography–atmospheric pressure chemical ionization–tandem mass spectrometry (GC-APCI–MS/MS). Based on the tertile distribution of total PBDEs concentrations in 59 participants, metabolomics analysis was further performed by ultra-high performance liquid chromatography coupled to hybrid quadrupole–Orbitrap MS. In the partial correlation analysis, the 29 identified metabolites were correlated with PBDEs exposure (P < 0.05). In addition, PBDEs disrupted the metabolism of glycerophospholipids, sphingolipids, taurine, and hypotaurine, indicating that neurotransmitters, oxidative stress, and inflammation are the vulnerable pathways affected in PTC. Furthermore, (±)-octopamine and 5-hydroxyindole, both of which modulate the actions of neurotransmitters, emerged as potential disturbed metabolite markers for TC following exposure to PBDEs. This study analyzed the impact of PBDEs on PTC in terms of the metabolic changes and further explored possible biomarkers, which helped us have a deep understanding of the possible mechanism of the effects of PBDEs on TC.

Advancing structural elucidation of conjugation drug metabolites in metabolite profiling with novel electron-activated dissociation.

This study focuses on the advantage of using the novel electron-activated dissociation (EAD) technology on the QTOF system for structural elucidation of conjugation metabolites. In drug metabolite identification, conceptual "boxes" are generally used to represent potential sites of modifications, which are proposed based on MS/MS data. Electron-activated dissociation (EAD) provides unique fragmentation patterns, potentially allowing for more precise localization of the metabolic modification sites compared to CID, particularly for conjugations. Known compounds were incubated with rat liver microsomes in the presence of nicotinamide adenine dinucleotide phosphate (NADPH), uridine dihosphate-glucuronic acid (UDPGA), and glutathione. Conjugation metabolites were analyzed using the QTOF system. High-resolution MS/MS spectra were collected using EAD and CID fragmentations along with TOF MS full scan for tested drugs and metabolites. Fragmentation patterns were compared to evaluate their efficiency in structural elucidation. Metabolite profiling identified conjugation metabolites (glucuronides and GSH adducts), using characteristic mass shifts. A comparison of EAD and CID fragmentation revealed EAD-specific fragments for most conjugates. EAD was able to break the relatively stable bonds on parent drug motifs while keeping relatively weak conjugation bonds intact, despite the generally low intensity of EAD. EAD effectively narrowed the conceptual "box" representing modification sites, providing more definitive information on conjugation sites and facilitating the structural elucidation of conjugated metabolites. EAD is a powerful tool for metabolite profiling in drug development, particularly for identifying conjugation sites. EAD-enabled MS/MS spectra offer a greater variety of signature fragments compared to CID, resulting in more comprehensive and unique structural information for metabolic modification analysis. Overall, EAD, complementary to CID, has the potential to narrow down potential modification sites, significantly enhancing the precision of conjugation metabolite structure elucidation.

The Potential of Deleterious rhizobacteria to Control Primary Weed &lt;i&gt;Echinochloa &lt;/i&gt;sp. on Rice

Deleterious rhizobacteria (DRB) is one of the rhizobacteria that can be used as a bioherbicide and can stimulate plant growth. The objectives that can be obtained from this study are to determine the potential of DRB on the growth of weeds Echinochloa crusgalli and Echinochloa colona on rice. Variables observed in this study were identification of secondary metabolites, measurement of weed sprouts, percentage effectiveness of bacterial isolates against weed seeds, normal sprouts, abnormal sprouts, fresh seeds that did not grow and dead seeds. The aim of this study is to explore biological agents that can be used to control the main weeds of rice crops. This candidate could be a recommendation for environmentally friendly controls. Exploration of the DRB group was obtained by collecting soil samples around the roots of rice crops. Then isolate it, identify as morphologically and physiologically, and test it in vitro studies. The results showed that DRB had the potential to control weed growth and could stimulate the growth of rice. The application of PFA and PFB isolates had a significant effect on inhibiting the length of weed roots and buds, the average percentage of control effectiveness &gt; 80-90%. Novelty in this study could be found as candidate groups of DRB bacteria with specific locations to control the weed Echinochloa sp. on rice crops. For society, this research could be an alternative to reduce dependence on synthetic herbicides . DRB has the potential to be formulated into a bioherbicide to control weeds.

Genome Mining and Genetic Manipulation Reveal New Isofuranonaphthoquinones in Nocardia Species.

The identification of specialized metabolites isolated from microorganisms is urgently needed to determine their roles in treating cancer and controlling multidrug-resistant pathogens. Naphthoquinones act as anticancer agents in various types of cancers, but some toxicity indicators have been limited in their appropriate application. In this context, new isofuranonaphthoquinones (ifnq) that are less toxic to humans could be promising lead compounds for developing anticancer drugs. The aim of this study is to identify and characterize novel furanonaphthoquinones (fnqs) from Nocardia sp. CS682 and to evaluate their potential therapeutic applications. Analysis of the genome of Nocardia sp. CS682 revealed the presence of a furanonaphthoquinone (fnq) gene cluster, which displays a similar genetic organization and high nucleotide sequence identity to the ifnq gene cluster from Streptomyces sp. RI-77, a producer of the naphthoquinones JBIR-76 and JBIR-77. In this study, the overexpression of the Streptomyces antibiotic regulatory protein (SARP) in Nocardia sp. CS682DR (nargenicin gene-deleted mutant) explicitly produced new fnqs, namely, NOC-IBR1 and NOC-IBR2. Subsequently, the role of the SARP regulator was confirmed by gene inactivation using CRISPR-Cas9 and complementation studies. Furthermore, antioxidant, antimicrobial, and cytotoxicity assays were performed for the isolated compounds, and it was found that NOC-IBR2 exhibited superior activities to NOC-IBR1. In addition, a flexible methyltransferase substrate, ThnM3, was found to be involved in terminal methylation of NOC-IBR1, which was confirmed by in vitro enzyme assays. Thus, this study supports the importance of genome mining and genome editing approaches for exploring new specialized metabolites in a rare actinomycete called Nocardia.

An isotopically-labelled temporal mass spectrometry imaging data analysis workflow to reveal glucose spatial metabolism patterns in bovine lens tissue

Application of stable isotopically labelled (SIL) molecules in Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging (MALDI-MSI) over a series of time points allows the temporal and spatial dynamics of biochemical reactions to be tracked in a biological system. However, these large kinetic MSI datasets and the inherent variability of biological replicates presents significant challenges to the rapid analysis of the data. In addition, manual annotation of downstream SIL metabolites involves human input to carefully analyse the data based on prior knowledge and personal expertise. To overcome these challenges to the analysis of spatiotemporal MALDI-MSI data and improve the efficiency of SIL metabolite identification, a bioinformatics pipeline has been developed and demonstrated by analysing normal bovine lens glucose metabolism as a model system. The pipeline consists of spatial alignment to mitigate the impact of sample variability and ensure spatial comparability of the temporal data, dimensionality reduction to rapidly map regional metabolic distinctions within the tissue, and metabolite annotation coupled with pathway enrichment modules to summarise and display the metabolic pathways induced by the treatment. This pipeline will be valuable for the spatial metabolomics community to analyse kinetic MALDI-MSI datasets, enabling rapid characterisation of spatio-temporal metabolic patterns from tissues of interest.

Fourier Transform Ion Cyclotron Resonance Mass Spectrometry Applications for Metabolomics.

Metabolomics is an interdisciplinary field that aims to study all metabolites < 1500 Da that are ubiquitously found within all organisms. Metabolomics is experiencing exponential growth and commonly relies on high-resolution mass spectrometry (HRMS). Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) is a form of HRMS that is particularly well suited for metabolomics research due to its exceptionally high resolution (105-106) and sensitivity with a mass accuracy in parts per billion (ppb). In this regard, FT-ICR-MS can provide valuable insights into the metabolomics analysis of complex biological systems due to unique capabilities such as the easy separation of isobaric and isomeric species, isotopic fine structure analysis, spatial resolution of metabolites in cells and tissues, and a high confidence (<1 ppm mass error) in metabolite identification. Alternatively, the large and complex data sets, long acquisition times, high cost, and limited access mainly through national mass spectrometry facilities may impede the routine adoption of FT-ICR-MS by metabolomics researchers. This review examines recent applications of FT-ICR-MS metabolomics in the search for clinical and non-human biomarkers; for the analysis of food, beverage, and environmental samples; and for the high-resolution imaging of tissues and other biological samples. We provide recent examples of metabolomics studies that highlight the advantages of FT-ICR-MS for the detailed and reliable characterization of the metabolome. Additionally, we offer some practical considerations for implementing FT-ICR-MS into a research program by providing a list of FT-ICR-MS facilities and by identifying different high-throughput interfaces, varieties of sample types, analysis methods (e.g., van Krevelen diagrams, Kendrick mass defect plot, etc.), and sample preparation and handling protocols used in FT-ICR-MS experiments. Overall, FT-ICR-MS holds great promise as a vital research tool for advancing metabolomics investigations.

Identification of Amino Acids and Polyphenolic Metabolites in Human Plasma by UHPLC-ESI-QTOF-MS/MS, after the Chronic Intake of a Functional Meal in an Elderly Population.

Novel foods especially formulated and targeted for the elderly population should provide sufficient nutrients and bioactive ingredients to counteract the natural age-related deterioration of various organs and tissues. Dietary protein and phenolic compounds achieve this goal; however, older adults have alterations in their gastrointestinal system that may impact their bioavailability and few studies have been aimed at this population. Since phenolic compounds are the subject of multiple biotransformations by host and microbiome enzymes during the digestion process, identification of their bioavailable forms in human plasma or tissues represents a considerable analytical challenge. In this study, UHPLC-ESI-QTOF/MS-MS, chemometrics, and multivariate statistical methods were used to identify the amino acids and phenolic compounds that were increased in the plasma of elderly adults after a 30-day intervention in which they had consumed an especially formulated muffin and beverage containing Brosimum alicastrum Sw. seed flour. A large interindividual variation was observed regarding the amino acids and phenolic metabolites identified in the plasma samples, before and after the intervention. Three phenolic metabolites were significantly increased in the population after the intervention: protocatechuic acid, 5-(methoxy-4'-hydroxyphenyl) valerolactone, and phloretic acid. These metabolites, as well as others that were not significantly increased (although they did increase in several individuals), are probably the product of the microbiota metabolism of the major phenolic compounds present in the B. alicastrum Sw. seed flour and other food ingredients. A significant decrease in 4-ethyl-phenol, a biomarker of stress, was observed in the samples. Results showed that the incorporation of foods rich in phenolic compounds into the regular diet of older adults contributes to the increase in bioactive compounds in plasma, that could substantially benefit their mental, cardiovascular, and digestive health.

Evaluation of Antioxidant Potential, Enzyme Inhibition, and Chemical Profiling Through Mass Spectrometry on Bark Extract of Berberis aristata

Berberis aristata, a plant from the Berberidaceae family, is renowned for its medicinal properties. The presence of bioactive metabolites in its bark underscores its importance in traditional medicine and pharmacology. This study primarily focuses on the biological activities of the plant bark extract, specifically its antioxidant properties and alpha-glucosidase inhibition. In addition to these activities, mass spectrometry-based compound annotation was conducted to explore the metabolites present in the plant bark extract. In this study, the bark samples were collected and extracted using the cold percolation method with methanol. Subsequently, an ethyl acetate fraction was obtained from the methanol extract using a separating funnel. The methanol extract of the bark showed a total phenolic content (TPC) of 70.056 ± 2.52 mg GAE/g and a total flavonoid content (TFC) of 11.89 ± 0.16 mg QE/g. To determine the antioxidant activity of the samples, a DPPH assay was used. The ethyl acetate fraction of the bark showed potent antioxidant activity with an IC50 value of 188.93 ± 8.35 μg/mL, while the methanol extract of the bark showed radical scavenging activity with an IC50 value of 242.89 ± 4.62 μg/mL. In terms of alpha-glucosidase inhibition, the methanol extract of the bark had low enzyme inhibition activity, but the ethyl acetate fraction exhibited potential inhibition with an IC50 value of 112.99 ± 10.28 µg/mL. These results indicate that the plant bark extract is rich in phenolic content compared to flavonoid content. Additionally, the ethyl acetate fraction of the plant bark exhibits potent radical scavenging activity and inhibition of the digestive enzyme alpha-glucosidase. Mass spectrometric-based identification of metabolites revealed that the methanol extract of the bark contains compounds such as Palmatin, columbamine, and berberal. The presence of these metabolites further supports the medicinal use of this plant bark. These findings enhance the plant's potential in the drug discovery process in the future.

Elucidating the Potential Role of Microorganisms in Postmortem Biotransformation: A Comparison of Clonazolam and its Metabolite in Postmortem and DUID Cases.

Clonazolam is a designer triazolobenzodiazepine first synthesized in 1971 and primarily used for its anxiolytic and sedative effects. It became a drug of misuse in 2012 and is known for its high potency and long duration of effects. Previous studies of nitrobenzodiazepines such as nitrazepam, clonazepam, flunitrazepam, and their metabolites have demonstrated that bacterial species native to the gastrointestinal tract and active during postmortem (PM) decomposition are capable of affecting positivity and compound-to-metabolite ratios. Further studies have not been performed with clonazolam; however, it possesses the nitro functional group necessary for this biotransformation. To understand whether clonazolam may be similarly affected, PM (n = 288) and driving under the influence of drugs (DUID, n = 54) cases positive for 8-aminoclonazolam reported by NMS Labs from 2020 to 2023 were selected for inclusion in this study. Concentrations of clonazolam and 8-aminoclonazolam were evaluated, and concurrent identification of parent drug and metabolite occurred less frequently in PM cases (n = 1, 0.30% of cases) than in DUID cases (n = 21, 38% of cases). The clonazolam concentration in one PM case was 13 ng/mL. In DUID cases the median clonazolam concentration was 4.0 ng/mL and ranged from 2.0-10 ng/mL. 8-Aminoclonazolam had median concentrations of 13 and 19 ng/mL and ranges of 2.0-580 and 2.8-59 ng/mL for PM and DUID cases, respectively. Due to the everchanging landscape of the DBZD market, in vitro studies of PM microbial biotransformation of clonazolam are unavailable. The data reported herein provide valuable information in the absence of such studies and represent an alternative method of investigating this phenomenon as a potential cause of parent nitrobenzodiazepine to metabolite conversion.

Identification of Secondary Metabolites by UHPLC-ESI-HRMS/MS in Antifungal Strain Trichoderma harzianum (LBAT-53).

Trichoderma spp. are filamentous fungi generally observed in nature, which are widely marketed as biocontrol agents. The secondary metabolites produced have obtained special attention since they possess attractive chemical structures with a broad spectrum of biological activities. In Cuba, the species of Trichoderma have been commercially applied for the control of several phytopathogens to protect agricultural crops, but few studies have been carried out to detect and characterize the production of metabolites with biological activity. The strain Trichoderma harzianum LBAT-53 was subjected to an antifungal in vitro assay against Fusarium oxysporum f.sp. cubense by dual culture and volatile metabolite assays and fermented in PDB under constant agitation conditions. The ethyl acetate crude extract was obtained by liquid-liquid extraction. The fungal extract was investigated for the composition of secondary metabolites through chemical screening and ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in negative ionization mode. As a result, LBAT-53 showed antagonistic activity in vitro (Class 2) against the pathogen evaluated in direct confrontation (76.9% of inhibition in 10 days) and by volatile metabolites (<40% in 7 days). Furthermore, seven low-molecular-weight phenolic compounds, including chrysophanol, phomarin, endocrocin, and trichophenol A, among others, were identified using UHPLC-ESI-MS/MS. This study is the first work on the characterization of secondary metabolites produced by the commercially applied strain LBAT-53, which is a promising source of bioactive compounds. These results provide a better understanding of the metabolism of this fungus, which is widely used in Cuba as biopesticides in agriculture pest control.

Identification of serum metabolites associated with aristolochic acid nephropathy severity and insights into the underlying mechanism

Aristolochic acid nephropathy (AAN) is a rapidly progressive kidney disease caused by medical or environmental exposure to aristolochic acids (AAs). This study aimed to identify serum metabolites associated with the severity of acute AAN and investigate the underlying mechanisms. Male C57BL/6 mice were treated with vehicle and 3 doses of aristolochic acid I (AAI) (1.25, 2.5, and 5 mg/kg/d) for 5 days by intraperitoneal injection. The results showed that AAI dose-dependently increased blood urea nitrogen (BUN) and serum creatinine (Scr) levels and renal pathological damage. Non-targeted metabolomics revealed that differences in serum metabolite profiles from controls increased with increasing AAI doses. Compared with the control group, 56 differentially expressed metabolites (DEMs) that could be affected by all 3 doses of AAI were obtained. We further identified 13 DEMs whose abundance significantly correlated with Scr and BUN levels and had good predictive values for diagnosing AAI exposure. Among the 13 DEMs, lipids and lipid-like molecules constituted the majority. Western blotting found that AAI suppressed renal fatty acid oxidation (FAO)-related enzymes expression. In conclusion, these findings provided evidence for developing biomarkers for monitoring AAs exposure and AAN diagnosis and indicated activation of FAO as a potential direction for the treatment of AAN.

Comparative Targeted Metabolomics of Ischemic Stroke: Thrombi and Serum Profiling for the Identification of Stroke-Related Metabolites.

Ischemic stroke is one of the leading causes of death and permanent disability in the world. Rapid diagnosis and intervention are crucial for reducing its consequences on individuals and societies. Therefore, identifying reliable biomarkers for early detection, prognostics, and therapy can facilitate the early prediction and prevention of stroke. Metabolomics has been shown as a promising tool for biomarker discovery since many post-ischemic metabolites can be found in the plasma or serum of the patient. In this research, we performed a comparative targeted metabolomic analysis of stroke thrombi, stroke patient serums, and healthy control serums in order to determine the alteration in the patients' metabolomes, which might serve as biomarkers for early prediction or stroke prevention. The most statistically altered metabolites characterized in the patient serums compared with the control serums were glutamate and serotonin, followed by phospholipids and triacylglycerols. In stroke thrombi compared with the patients' serums, the most significantly altered metabolites were classified as lipids, with choline-containing phospholipids and sphingomyelins having the highest discriminatory score. The results of this preliminary study could help in understanding the roles of different metabolic changes that occur during thrombosis and cerebral ischemia and possibly suggest new metabolic biomarkers for ischemic stroke.

Identification and characterization of transition metal-binding proteins and metabolites in the phloem sap of Brassica napus

Transition metal (TM) distribution through the phloem is an essential part of plant metabolism and is required for systemic signaling and balancing source-to-sink relationships. Due to their reactivity, TMs are expected to occur in complexes within the phloem sap; however, metal speciation in the phloem sap remains largely unexplored. Here, we isolated phloem sap from Brassica napus and analyzed it via size exclusion chromatography (SEC) coupled online to sector-field ICP-MS. Our data identified known TM binding proteins and molecules including metallothioneins (MT), glutathione, and nicotianamine. While the main peak of all metals was low MW (∼1.5 kD), additional peaks ∼10-15 kD containing Cu, Fe, S and Zn were also found. Further physicochemical analyses of MTs with and without affinity tags corroborated that MTs can form complexes of diverse molecular weights. We also identified and characterized potential artifacts in the TM-biding ability of B. napus MTs between tagged and non-tagged MTs. That is, the native BnMT2 binds Zn, Cu and Fe, while MT3a and MT3b only bind Cu and Zn. In contrast, his-tagged MTs bind less Cu and were found to bind Co and Mn and aggregated to oligomeric forms to a greater extent compared to the phloem sap. Our data indicates that TM chemistry in the phloem sap is more complex than previously anticipated and that more systematic analyses are needed to establish the precise speciation of TM and TM-ligand complexes within the phloem sap.

Identification of candidate exposure biomarkers for acetyl tributyl citrate and acetyl triethyl citrate using suspect screening in human liver microsomes

Acetyl tributyl citrate (ATBC) and acetyl triethyl citrate (ATEC) are increasingly used as alternatives to phthalates in various products, including food packaging, medical devices, and personal care items, raising concerns about their potential health impacts. This study aimed to investigate the in vitro human metabolism of ATBC and ATEC and identify potential exposure biomarkers applicable in human biomonitoring. Pooled human liver microsomes were utilized to conduct in vitro metabolism assays of deuterium labeled ATBC (ATBC-d3) and ATEC, and liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (LC-qToF/MS) was employed for analysis. Suspect screening workflow and confidence level assignment were applied for metabolite identification. Time-course analysis revealed rapid metabolism of both compounds, with estimated apparent half-lives of approximately 5 min for ATBC-d3 and less than 15 min for ATEC. Eleven metabolites were identified for ATBC-d3 and six for ATEC. The predominant chemical reactions observed were carboxylic ester hydrolysis, deacetylation, and hydroxylation. Based on their abundance and specificity, MB1 (hydroxylated) and MB11 (hydrolyzed and hydroxylated) were proposed as candidate exposure biomarkers for ATBC, and ME1 (hydrolyzed and deacetylated) for ATEC. The identified metabolites and proposed sequences of kinetic process enhance our understanding of the fate of these compounds in the human body, potentially informing future toxicological assessments and guiding the development of more comprehensive human biomonitoring strategies.

Metabolism study of 3-chloromethcathinone (3-CMC) by dried blood spot (DBS) sampling after controlled administration using a murine model.

The metabolism of 3-chloromethcathinone (3-CMC) was studied after controlled administration in a murine model using the dried blood spot (DBS) technique for the sampling, storage and purification of blood samples. Liquid chromatography-high-resolution mass spectrometry (LC-HRMS) was used for the identification of metabolites and investigation of their fragmentation pattern. Subsequently, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for their identification and 3-CMC quantification in routine workload. The main metabolites identified were two stereoisomers of dihydro-CMC, N-demethyl-CMC, and dihydro-N-demethyl-CMC. The stability of 3-CMC and of its metabolites deposited on DBS was evaluated by replicate analyses after 30, 50, and 90 days, demonstrating a decrease in concentration. It was more pronounced for 3-CMC, with -67% and -82% percentage deviation from the initial concentrations, and for N-demethyl 3-CMC (decrease comprised between -48% and -88%) than for the di-hydro metabolites, ranging from -5% to -37%. Regardless, all of them were detectable till 90 days after deposition as DBS. The possibility of identifying 3-CMC and its metabolites with high sensitivity is an invaluable tool for the diagnosis of exposure to the substance, also in low doses or after some hours, and for various applications in clinical and forensic toxicology, such as driving under the influence, drug-facilitated crimes, and addiction to intoxications. DBS demonstrated to be a reliable technique for the sampling, storage, and purification of the blood specimen for 3-CMC and metabolite detection.

Untargeted metabolomics study of mature human milk from women with and without gestational diabetes mellitus

Gestational diabetes mellitus (GDM) is a prevalent metabolic disorder during pregnancy that alters the metabolites in human milk. Integrated Gas Chromatography-Mass Spectrometry (GC–MS) and Liquid Chromatography-Mass Spectrometry (LC-MS) were employed for comprehensive identification and comparison of metabolites in mature human milk (MHM) from women with and without GDM. A total of 268 differentially expressed metabolites (DEMs) were identified. Among these, linoleic acid, arachidonic acid, 9R-HODE and L-glutamic acid were significantly elevated and 12,13-DHOME was significantly decreased in MHM of women with GDM. These metabolites are significantly enriched in linoleic acid metabolism, fatty acid biosynthesis, galactose metabolism and ABC transporters pathways. Disorders in these metabolic pathways are associated with insulin resistance and poor glucose metabolism indicating these conditions may persist postpartum.

Development of LC-MS/MS methods affording identification and measurement of active metabolites in rat and dog plasma after oral dosing of a penta-ethyl ester prodrug of diethylenetriamine pentaacetic acid

Development of LC-MS/MS methods affording identification and measurement of active metabolites in rat and dog plasma after oral dosing of a penta-ethyl ester prodrug of diethylenetriamine pentaacetic acid