Ultrahigh-performance Liquid Chromatography-tandem Mass Spectrometry Research Articles

Development of a high-throughput UHPLC-MS/MS method for the analysis of Fusarium and Alternaria toxins in cereals and cereal-based food.

A QuEChERS (quick, easy, cheap, effective, rugged, and safe)-based multi-mycotoxin method was developed, analyzing 24 (17 free and 7 modified) Alternaria and Fusarium toxins in cereals via ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). A modified QuEChERS approach was optimized for sample preparation. Quantification was conducted using a combination of stable isotope dilution analysis (SIDA) for nine toxins and matrix-matched calibration for ten toxins. Quantification via a structurally similar internal standard was conducted for four analytes. Alternariol-9-sulfate (AOH-9-S) was measured qualitatively. Limits of detection (LODs) were between 0.004µg/kg for enniatin A1 (ENN A1) and 3.16µg/kg for nivalenol (NIV), while the limits of quantification were between 0.013 and 11.8µg/kg, respectively. The method was successfully applied to analyze 136 cereals and cereal-based foods, including 28 cereal-based infant food products. The analyzed samples were frequently contaminated with Alternaria toxins, proving their ubiquitous occurrence. Interestingly, in many of those samples, some modified Alternaria toxins occurred, mainly alternariol-3-sulfate (AOH-3-S) and alternariol monomethyl ether-3-sulfate (AME-3-S), thus highlighting the importance of including modified mycotoxins in the routine analysis as they may significantly add to the total exposure of their parent toxins. Over 95% of the analyzed samples were contaminated with at least one toxin. Despite the general contamination, no maximum or indicative levels were exceeded.

Eco-friendly one-step egg white gel preparation for sensitive detection of 13 trichothecenes in oats using UHPLC-MS/MS.

Oat products have gained widespread recognition as a health food due to their rich and balanced nutritional profile and convenience. However, the unique matrix composition of oats, which differs significantly from other cereals, presents specific challenges for mycotoxin analysis. This study presents an ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method enhanced with an innovative egg white gel pretreatment for the simultaneous analysis of 13 regulated and unregulated trichothecenes in oats. The method demonstrated excellent performance with high accuracy (> 87.5%), repeatability (< 5.7%), and reproducibility (< 8.1%). Analysis of 100 commercial oat products revealed a concerning detection rate (78%) for at least one of the 11 trichothecenes investigated. Notably, deoxynivalenol, exceeding the standard limit in 2% of samples, exhibited the highest detection rate (62%). Additionally, concerning co-occurrence patterns and positive correlations were observed, highlighting potential synergistic effects. The first-time detection of unregulated mycotoxins (T-2 triol, 4,15-diacetoxyscirpenol, 15-acetoxyscirpenol, and neosolaniol) underscores the need for comprehensive monitoring. This method, while developed for oats, shows potential for broader application to other cereals, though further investigation and confirmation are necessary. These findings suggest a potentially underestimated risk of trichothecenes in oats, necessitating continuous monitoring to ensure consumer safety.

A dual-recognition strategy based on pH-responsive molecularly imprinted membrane for highly selective capture of catecholamines: From construction to practical application

BackgroundCatecholamines (CAs) are involved in a wide range of physiological and pathological processes in the body and are progressively being used as important biomarkers for a variety of diseases. It is of great significance for accurate quantification of CAs to the diagnosis and treatment of diseases. However, the separation of CAs from complex biological matrices is still a great challenge due to the trace levels of CAs and the limited selectivity of existing pretreatment methods. ResultsIn this work, a dual-recognition imprinted membrane (BA-MIM) was developed to utilize the synergistic action of pH-responsive boron affinity and molecular imprinted cavities for highly selective capture and release of CAs. The prepared BA-MIM possessed remarkable adsorption capacity (maximum capacity, 43.3 mg g−1), desirable surface hydrophilicity (46.2°), superior selectivity (IF = 6.2, α = 14.3), as well as favorable reusability (number of cycles, 6 times). On this basis, an integrated analytical method based on BA-MIM extraction combined with ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was innovatively developed to highly selective separation, enrichment, and detection of CAs in rat brain tissue. Under the optimum conditions, a low quantitation limits (0.05–0.10 ng mL−1), wide linear range (10–1000 ng mL−1), good linearity (r2 > 0.99), and satisfactory recoveries (88.5%–98.5 %) were obtained for CAs. The proven method was further applied to kidney-yang-deficiency-syndrome (KYDS) group rat model, revealed the intrinsic connection between kidney disease and catecholamine metabolism. SignificanceThis work provides an excellent reference paradigm for the effective construction of dual-recognition functional membrane material to the high-selective analysis of trace targets in complex matrices. Additionally, this integrated analytical strategy demonstrates its efficiency, sustainability, versatility, and convenience, showing remarkable prospect in a variety of applications for biological sample analysis.

P-glycoprotein-mediated herb-drug interaction evaluation between Tenacissoside G and paclitaxel.

P-glycoprotein (P-gp)-mediated herb-drug interactions (HDIs) may impact drug efficacy and safety. Tenacissoside G (Tsd-G), a major active component of Marsdenia tenacissima, exhibits anticancer activity. To analyze the effect of Tsd-G on the pharmacokinetics of paclitaxel (PTX), researchers selected 30 Sprague-Dawley (SD) rats, randomized into a solvent control group, a verapamil positive control group, and 20, 40, and 60 mg/kg Tsd-G groups. After seven consecutive days of intraperitoneal injection of verapamil or Tsd-G, a single dose of 6 mg/kg PTX was injected intravenously. Plasma samples were collected at different time points, and proteins were precipitated using a methanol-acetonitrile solution. An ultrahigh-performance liquid chromatography-tandem mass spectrometry method was developed, with docetaxel as an internal standard, and quantified using positive ion multiple reaction monitoring (MRM) mode. This analytical method's specificity, accuracy, precision, recovery, matrix effect, and sample stability meet the requirements for biological sample determination. After Tsd-G administration in rats, the mean residence time of PTX was significantly prolonged. And Tsd-G can stably bind to P-gp by forming hydrogen bonds and inhibiting the expression of P-gp in rat liver. Although the metabolites of PTX were not detected in this study, the above results still indicate the existence of HDIs between Tsd-G and PTX, and P-gp may be the main target to mediate HDIs.

Molecular Changes during Germination of Cocoa Beans, Part 2.

A recently published untargeted metabolomics approach toward marker compounds of cocoa germination revealed and identified 12-hydroxyjasmonic acid sulfate, (+)-catechin, and (-)-epicatechin as the most downregulated compounds and two hydroxymethylglutaryl glucosides (HMG gluc) A and B, among others, as the decisive upregulated compounds in the germinated material. These findings were quantitatively evaluated using ultrahigh-performance liquid chromatography-tandem mass spectrometry not only in previously examined sample material but also in a vastly expanded array of cocoa samples of different provenience and process and in cocoa products such as cocoa liquor and chocolate. Hereby, yields of newly identified HMG gluc derivatives could be determined in raw, fermented, germinated, and alternatively processed cocoa, and isomers of HMG gluc A and B could be established as key process indicators. Based on unsupervised clustering and supervised classification, models could identify germinated samples in testing sets consisting of raw, fermented, and germinated samples.

Integrated proteomic and metabolomic profiling reveals novel insights on the inflammation and immune response in HFpEF

BackgroundThe precise mechanisms leading to the development of heart failure with preserved ejection fraction (HFpEF) remain incompletely defined. In this study, an integrative approach utilizing untargeted proteomics and metabolomics was employed to delineate the altered proteomic and metabolomic profiles in patients with HFpEF compared to healthy controls.Materials and methodsData were collected from a prospective cohort consisting of 30 HFpEF participants and 30 healthy controls, matched by gender and age. plasma samples were analyzed by multi-omics platforms. The quantification of plasma proteins and metabolites was performed using data-independent acquisition-based liquid chromatography-tandem mass spectrometry (LC-MS/MS) and ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), respectively. Additionally, Proteomic and metabolomic results were analyzed separately and integrated using correlation and pathway analysis. This was followed by the execution of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment studies to elucidate the biological relevance of the observed results.ResultsA total of 46 significantly differentially expressed proteins (DEPs) and 102 differentially expressed metabolites (DEMs) were identified. Then, GO and KEGG pathway enrichment analyses were performed by DEPs and DEMs. Integrated analysis of proteomics and metabolomics has revealed Tuberculosis and African trypanosomiasis pathways that are significantly enriched and the DEPs and DEMs enriched within them, are associated with inflammation and immune response.ConclusionsIntegrated proteomic and metabolomic analyses revealed distinct inflammatory and immune response pathways in HFpEF, highlighting novel therapeutic avenues.

Occurrence and mechanism of sulfamethoxazole in alginate-like extracellular polymers from excess sludge

The recovery of biopolymers, particularly alginate-like extracellular polymers, from municipal sludge represents a promising step toward sustainable sludge treatment practices. Originating from wastewater plants in complexly polluted environments, alginate-like extracellular polymers carry potential environmental risks concerning their reuse. This study employs ultrahigh-performance liquid chromatography–tandem mass spectrometry to investigate the distribution coefficients and occurrence of alginate-like extracellular polymers and sulfamethoxazole. Results demonstrate a negative distribution coefficient, suggesting an inhibitory effect on sulfamethoxazole dissolution. The ethanol-extracted alginate-like extracellular polymers exhibits higher sulfamethoxazole levels (approximately 52%) than those obtained via dialysis extraction. Three-dimensional excitation-emission matrix analysis and adsorption studies indicate the absence of tyrosine-like substances in the alginate-like extracellular polymers, unlike in other extracellular polymeric substances. This absence diminishes hydrophobic interactions, highlighting that electrostatic interactions play a more important role. These insights are crucial for understanding the adsorption behavior of alginate-like extracellular polymers and optimizing their large-scale extraction processes.

Phytochemical Investigation of Polyphenols from the Aerial Parts of Tanacetum balsamita Used in Transylvanian Ethnobotany and Parallel Artificial Membrane Permeability Assay.

In this study, based on ethnobotanical data recorded in Transylvania, the polyphenolic compounds and the permeability of the aerial part's extract of Tanacetum balsamita were investigated. Ultrahigh-performance liquid chromatography-tandem mass spectrometry was applied for the analysis of the extracts. Parallel artificial membrane permeability assay (PAMPA) for the gastrointestinal tract and the blood-brain barrier was conducted. In the ethanolic and aqueous extracts of the species traditionally used for wound, furuncle, and liver disorders, 92 polyphenols were characterized (e.g., flavonoid, hydroxycinnamic acid, catechin, dihydroxybenzoyl, lignan derivatives, and a monoterpene) including 54 compounds identified for the first time in the plant. In the PAMPA tests, eight components were shown to be capable of passive diffusion across the studied membranes. These include apigenin and seven methoxylated flavonoid derivatives. Based on these results, methoxylated flavonoids might promote the pharmacological potential of T. balsamita to be applied in the enhancement of novel remedies.

Metabolomics signatures of air pollution mixtures and lung cancer risk: A large-scale metabolome-wide association study in the Cancer Prevention Study cohorts.

10571 Background: Despite the well-established link between air pollution exposure and lung carcinogenesis, the underlying mechanism remains underexplored. While metabolomics has provided valuable molecular insights, existing air pollution metabolomics studies only assess biological changes to single air pollutants, without examining the join effects of air pollutant mixtures. We sought to identify metabolic signatures mediating the association between ambient air pollution mixtures and lung cancer risk. Methods: A total of 603 matched lung cancer case-control pairs were selected from the Cancer Prevention Study cohorts. Controls were matched to cases on age at blood draw, sex, race/ethnicity, and blood draw date. Plasma metabolomics was conducted using ultrahigh-performance liquid chromatography-tandem mass spectrometry. Air pollution mixtures include carbon monoxide, nitrogen dioxide, particulate matter, sulfur dioxide, and ozone, matched to subjects’ residential address at blood draw. We conducted an untargeted metabolome-wide association study with multivariable-adjusted linear and conditional logistic regression models to assess associations between metabolites and individual air pollutants and lung cancer risk, respectively, adjusting for individual and lifestyle-related covariates. We used a meet-in-the-middle (MITM) approach to identify potential mediators. Quantile g-computation was used to examine the effects of air pollution mixtures on metabolome perturbations to analyze the collective effects of multiple air pollutants concurrently. Results: Among 1,138 extracted metabolic features, 162 were significantly associated with the combined mixture (false discovery rate &lt; 0.2). Using MITM, no metabolites were associated with both air pollution mixture and lung cancer risk at FDR &lt; 0.2. At raw p &lt; 0.05, 16 metabolites were identified as potential mediators of the air pollution mixture and lung cancer risk. These metabolites, including 4-hydroxyphenylacetylglutamine, glutamate, and 3-aminoisobutyrate, were also significantly associated with the mixture at FDR &lt; 0.2. Conclusions: Findings from this analysis demonstrate the feasibility of considering multiple air pollutants as mixtures when conducting air pollution-related metabolomics investigations. Future exploration of the underlying biological mechanisms will be critical for validating pathways that participate in air pollution carcinogenicity. As lung cancer cases in never smokers continue to increase, it is pertinent to study air pollution and other environmental risk factors on cancer incidence.

Determination of succinic acid and lactic acid in pigs' serum, intestinal contents, and meat by ultrahigh-performance liquid chromatography-tandem mass spectrometry.

Succinic acid and lactic acid have been associated with diarrhea in weaned piglets. The level of succinic acid and lactic acid in serum, meat, and intestinal contents is important to elucidate the mechanism of diarrhea in weaned piglets. A facile method was developed for the quantification of succinic acid and lactic acid in pigs' serum, intestinal contents, and meat using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC/MS/MS). The serum samples underwent protein precipitation with methanol. The meat and intestinal contents were freeze-dried and homogenized using a tissue grinding apparatus. Methanol-water mixture (80:20, v/v) was used for homogenizing the meat, while water was used for homogenizing the intestinal contents. An additional step of protein precipitation with acetonitrile was required for the intestinal contents. The resulting solution was diluted with water before being analyzed by UHPLC/MS/MS. Separation of succinic acid and lactic acid could be achieved within 3min using a Kinetic XB-C18 column. The coefficients of variation for peak areas of succinic acid and lactic acid were less than 5.0%. The established method demonstrated good linearity as indicated by correlation coefficients exceeding 0.996. Additionally, satisfactory recoveries ranging from 88.58% to 108.8% were obtained. The detection limits (RS/N = 3) for succinic acid and lactic acid were determined to be 0.75 ng/mL and 0.02 μg/mL, respectively. This method exhibited high sensitivity, simplicity in operation, and small sample weight, making it suitable for quantitative determination of succinic acid and lactic acid in pigs' serum, intestinal contents, and meat. The method developed will provide valuable technical support in studying the metabolic mechanisms of succinic acid and lactic acid in pigs.

Quantitative analysis of erythromycin, its major metabolite and clarithromycin in chicken tissues and eggs via QuEChERS extraction coupled with ultrahigh-performance liquid chromatography-tandem mass spectrometry

A simple, rapid and novel method involving ultrahigh-performance liquid chromatography-electrospray ionization tandem triple quadrupole mass spectrometry (UHPLC-ESI–MS/MS) was developed to simultaneously detect erythromycin, its major metabolite and clarithromycin in chicken tissues (muscle, liver and kidney) and eggs (whole egg, albumen and yolk). Samples were extracted using acetonitrile–water (80:20, v/v), and a Cleanert MAS-Q cartridge was used to perform quick, easy, cheap, effective, rugged, and safe (QuEChERS) purification. The average recoveries were 87.78–104.22 %, and the corresponding intraday and interday relative standard deviations were less than 7.10 %. The decision limits and detection capabilities of the chicken tissues and eggs were 2.15–105.21 μg/kg and 2.26–110.42 μg/kg, respectively. For chicken tissues and eggs, the limits of detection and limits of quantification were 0.5 μg/kg and 2.0 μg/kg, respectively. The proposed method was successfully employed to analyse real samples, demonstrating its applicability.

Covalent organic frameworks as dispersive solid-phase extraction adsorbents for β-lactam detection in aquatic environments

Currently, antibiotic residues in the environment pose a serious public health risk; therefore, new sensitive approaches for detecting the presence of antibiotics are urgently needed. Ionic-type covalent organic frameworks (TAPB-(TFIT)+Cl−-COFs) were designed and prepared in this work, and these imine-linked COFs were characterized by several techniques, proving of porous structure and rich of nitrogen. The materials were applied to the extraction of β-lactams from aqueous samples, and the important parameters of the adsorption–desorption conditions were optimized. A dispersive solid-phase extraction method coupled with ultrahigh-performance liquid chromatography-tandem mass spectrometry (TAPB-(TFIT)+Cl−-COFs-d-SPE-UPLC-MS/MS) was proposed and utilized to determine the levels of 11 antibiotics in the β-lactams in the extracted samples. Good linearity (1.0–200.0 μg·L−1, r > 0.9999) was achieved together with limits of detection and quantification of 0.01–0.92 μg·L−1 and 0.05–2.78 μg·L−1, respectively; recoveries ranged from 75.57 to 114.20 %, conferring relative standard deviations < 8.99 % and negligible matrix effects (84.88–109.40 %). The synthesized TAPB-(TFIT)+Cl−-COFs were demonstrated to have good reusability and high stability. Furthermore, the proposed method was clearly shown to be sensitive and separable for the reliable simultaneous detection of 11 β-lactam residues in aquatic environments.

High-sensitivity liquid chromatography-tandem mass spectrometry quantitative for alkyl imidazolium ionic liquids in human serum: Advancing biomonitoring of human exposure concerns

Alkyl imidazolium ionic liquids (Cn[MIM]), initially heralded as eco-friendly green solvents for diverse industrial applications, have increasingly been recognized fortheir biodegradability challenges and multiple biotoxicity. Despite potential health risks, research into the effects of Cn[MIM] on human health remains scarce, particularly regarding their detection in biological serum samples. This study validated a matrix-matched calibration quantitative method that utilizes solid-phase extraction (SPE) coupled with ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The method was used to analyze the presence of 10 ionic liquids (ILs) with varying alkyl carbon chain lengths (C2–C12) across 300 human serum samples. Efficient separation was achieved using optimized SPE conditions and a BEH C18 column with an appropriate mobile phase. Results demonstrated a strong linear relationship (0.05–100 ng/mL; R2 = 0.995–0.999), with detection and quantification limits with detection and quantification limits ranging from 0.001 to 0.107 ng/mL and 0.003–0.355 ng/mL, respectively. Intraday and inter-day precisions were 0.85–6.99 % and 1.50–7.46 %, with recoveries between 82 and 113 %. The validated method detected C6MIM in 19 % of samples and C8MIM in 8.3 % of samples, with concentrations ranging from 0.02 to 111.70 μg/L and 0.09–16.99 μg/L, respectively, suggesting a potential risk of human exposure. This underscores the importance of robust detection methods in monitoring environmental and human health impacts of alkyl imidazolium compounds.

A rapid solid-phase extraction purification combined with UPLC[sbnd]MS/MS used for simultaneous determination of eight tetracyclines and three metabolite in chicken and pork

A method for rapid detection and identification of 8 tetracyclines (TCs) and 3 metabolite residues in chicken and pork was established and verified by combining rapid solid-phase extraction (SPE) technology with ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLCMS/MS). After a sample was extracted, it was purified with a PRiME HLB cartridge, and the cartridge did not need to be activated, balanced, or eluted. The filtrate was dried under nitrogen, redissolved, and subsequently analyzed via UPLCMS/MS. The limits of detection for chicken and pork were 0.05–0.48 μg/kg and 0.05–0.52 μg/kg, respectively. The limits of quantification were 0.16–1.61 μg/kg and 0.16–1.75 μg/kg, respectively. The recoveries were 85.15%–107.50% and 84.21%–106.37%, respectively. The established method was suitable for qualitative and quantitative analyses of TCs and their metabolite residues in chicken and pork and has been used for the detection of TC in chicken and pork samples from local markets.

Metabolomic analysis reveals the changing trend and differential markers of volatile and nonvolatile components of Artemisiae argyi with different aging years.

Artemisia argyi Folium (AAF) is a traditional medicinal herb and edible plant. Analyzing the differential metabolites that affect the efficacy of AAF with different aging years is necessary. The aim of the study was to investigate the changing trend and differential markers of volatile and nonvolatile metabolites of AAF from different aging years, which are necessary for application in clinical medicine. Metabolites were analyzed using a widely targeted metabolomic approach based on ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography tandem mass spectrometry (GC-MS). A total of 153 volatile metabolites and 159 nonvolatile metabolites were identified. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) could clearly distinguish AAF aged for 1 year (AF-1), 3 years (AF-3), and 5 years (AF-5). Seven flavonoids and nine terpenoids were identified as biomarkers for tracking the aging years. The metabolomic method provided an effective strategy for tracking and identifying biomarkers of AAF from different aging years. This study laid the foundation for analysis of the biological activity of Artemisia argyi with different aging years.

Simultaneous Determination of Selected Steroids with Neuroactive Effects in Human Serum by Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Neuroactive steroids are a group of steroid molecules that are involved in the regulation of functions of the nervous system. The nervous system is not only the site of their action, but their biosynthesis can also occur there. Neuroactive steroid levels depend not only on the physiological state of an individual (person's sex, age, diurnal variation, etc.), but they are also affected by various pathological processes in the nervous system (some neurological and psychiatric diseases or injuries), and new knowledge can be gained by monitoring these processes. The aim of our research was to develop and validate a comprehensive method for the simultaneous determination of selected steroids with neuroactive effects in human serum. The developed method enables high throughput and a sensitive quantitative analysis of nine neuroactive steroid substances (pregnenolone, progesterone, 5α-dihydroprogesterone, allopregnanolone, testosterone, 5α-dihydrotestosterone, androstenedione, dehydroepiandrosterone, and epiandrosterone) in 150 μL of human serum by ultrahigh-performance liquid chromatography with tandem mass spectrometry. The correlation coefficients above 0.999 indicated that the developed analytical procedure was linear in the range of 0.90 nmol/L to 28.46 μmol/L in human serum. The accuracy and precision of the method for all analytes ranged from 83 to 118% and from 0.9 to 14.1%, respectively. This described method could contribute to a deeper understanding of the pathophysiology of various diseases. Similarly, it can also be helpful in the search for new biomarkers and diagnostic options or therapeutic approaches.

Chemoselectivity Strategy Based on B-Label Integrated with Tailored COF for Targeted Metabolomic Analysis of Short-Chain Fatty Acids by UHPLC-MS/MS.

Chemoselective extraction strategy is an emerging and powerful means for targeted metabolomics analysis, which allows for the selective identification of biomarkers. Short-chain fatty acids (SCFAs) as functional metabolites for many diseases pose challenges in qualitative and quantitative analyses due to their high polarity and uneven abundance. In our study, we proposed the B-labeled method for the derivatization of SCFAs using easily available 3-aminobenzeneboronic acid as the derivatization reagent, which enables the introduction of recognition unit (boric acid groups). To analyze the B-labeled targeted metabolites accurately, cis-diol-based covalent organic framework (COF) was designed to specifically capture and release target compounds by pH-response borate affinity principle. The COF synthesized by the one-step Schiff base reaction possessed a large surface area (215.77 m2/g), excellent adsorption capacity (774.9 μmol/g), good selectivity, and strong regeneration ability (20 times). Combined with ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis, our results indicated that the detection sensitivities of SCFAs increased by 1.2-2500 folds compared with unlabeled method, and the retention time and isomer separation were improved. Using this strategy, we determined twenty-six SCFAs in the serum and urine of rats in four groups about osteoporosis and identified important biomarkers related to the tricarboxylic acid cycle and fatty acid metabolism pathways. In summary, UHPLC-MS/MS based on B-labeled derivatization with tailored COF strategy shows its high selectivity, excellent sensitivity, and good chromatographic behavior and has remarkable application prospect in targeted metabolomics study of biospecimens.

Characterization of an Arginine Decarboxylase from Streptococcus pneumoniae by Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Polyamines are polycations derived from amino acids that play an important role in proliferation and growth in almost all living cells. In Streptococcus pneumoniae (the pneumococcus), modulation of polyamine metabolism not only plays an important regulatory role in central metabolism, but also impacts virulence factors such as the capsule and stress responses that affect survival in the host. However, functional annotation of enzymes from the polyamine biosynthesis pathways in the pneumococcus is based predominantly on computational prediction. In this study, we cloned SP_0166, predicted to be a pyridoxal-dependent decarboxylase, from the Orn/Lys/Arg family pathway in S. pneumoniae TIGR4 and expressed and purified the recombinant protein. We performed biochemical characterization of the recombinant SP_0166 and confirmed the substrate specificity. For polyamine analysis, we developed a simultaneous quantitative method using hydrophilic interaction liquid chromatography (HILIC)-based liquid chromatography-tandem mass spectrometry (LC-MS/MS) without derivatization. SP_0166 has apparent Km, kcat, and kcat/Km values of 11.3 mM, 715,053 min-1, and 63,218 min-1 mM-1, respectively, with arginine as a substrate at pH 7.5. We carried out inhibition studies of SP_0166 enzymatic activity with arginine as a substrate using chemical inhibitors DFMO and DFMA. DFMO is an irreversible inhibitor of ornithine decarboxylase activity, while DFMA inhibits arginine decarboxylase activity. Our findings confirm that SP_0166 is inhibited by DFMA and DFMO, impacting agmatine production. The use of arginine as a substrate revealed that the synthesis of putrescine by agmatinase and N-carbamoylputrescine by agmatine deiminase were both affected and inhibited by DFMA. This study provides experimental validation that SP_0166 is an arginine decarboxylase in pneumococci.

Perfluoropentane-based oxygen-loaded nanodroplets reduce microglial activation through metabolic reprogramming.

JOURNAL/nrgr/04.03/01300535-202504000-00032/figure1/v/2024-07-06T104127Z/r/image-tiff Microglia, the primary immune cells within the brain, have gained recognition as a promising therapeutic target for managing neurodegenerative diseases within the central nervous system, including Parkinson's disease. Nanoscale perfluorocarbon droplets have been reported to not only possess a high oxygen-carrying capacity, but also exhibit remarkable anti-inflammatory properties. However, the role of perfluoropentane in microglia-mediated central inflammatory reactions remains poorly understood. In this study, we developed perfluoropentane-based oxygen-loaded nanodroplets (PFP-OLNDs) and found that pretreatment with these droplets suppressed the lipopolysaccharide-induced activation of M1-type microglia in vitro and in vivo, and suppressed microglial activation in a mouse model of Parkinson's disease. Microglial suppression led to a reduction in the inflammatory response, oxidative stress, and cell migration capacity in vitro. Consequently, the neurotoxic effects were mitigated, which alleviated neuronal degeneration. Additionally, ultrahigh-performance liquid chromatography-tandem mass spectrometry showed that the anti-inflammatory effects of PFP-OLNDs mainly resulted from the modulation of microglial metabolic reprogramming. We further showed that PFP-OLNDs regulated microglial metabolic reprogramming through the AKT-mTOR-HIF-1α pathway. Collectively, our findings suggest that the novel PFP-OLNDs constructed in this study alleviate microglia-mediated central inflammatory reactions through metabolic reprogramming.

Profiling of urinary steroids aided by lithium ion adduction-based ultrahigh-performance liquid chromatography-tandem mass spectrometry.

As 3-OH-containing steroids are prone to dehydration by conventional electrospray ionization, reducing detection sensitivity, Li ion adduction-based ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC/MS/MS), developed to prevent dehydration and effectively detect 3-OH steroids, was applied for profiling total and free steroids in urine. Free urinary steroids were isolated directly from urine by solid-phase extraction (SPE) with 80% acetonitrile. The total steroids were prepared by enzymatic treatment of urine with a cocktail of sulfatase and glucronidase, protein precipitation, and separation with the above SPE. In order to detect as many steroid types as possible, UHPLC/MS/MS (Li method) with Li+ solution added after the column was used for analysis in addition to the conventional method of detecting protonated ions (H method). The 13 3-OH steroids and the remaining 16 steroids were quantified by standard curves prepared using product ion transitions derived from [M + Li]+ and MH+ , respectively. Two groups of human urine, male and female urine, were analyzed. 3-OH steroids could be detected with greater sensitivity using the Li method than the conventional method. The absolute amounts of each steroid were normalized based on creatinine levels. The difference between the male and female groups are clearly attributable to sex steroids. Twenty-nine total steroids and 19 free steroids were identified in a limited volume (240 mL) of urine. Of these, 13 3-OH steroids were better detected by Li+ adduction-based UHPLC/MS/MS.