High-resolution Mass Spectrometry Analysis Research Articles

High-throughput screening to identify endocrine disruptors: Contribution of low-resolution tandem MS and high-resolution MS.

Considering the large diversity of chemicals present in the environment and the need to study their effects (alone or as mixtures), the development of high-throughput in vitro assays in line with the Replacement, Reduction, Refinement (3R) strategy is essential for chemical risk assessments. We developed a robust analytical workflow based on both low resolution tandem mass spectrometry (MS/MS) and high-resolution mass spectrometry (HRMS) to quantify 13 steroids in NCI-H295R cell culture medium, human plasma and serum. The workflow was validated by screening media from the NCI-H295R cell line exposed in dose-response experiments to 5 endocrine disruptors (EDs) such as bisphenol A, prochloraz, ketoconazole, atrazine and forskolin. Absolute quantifications of the 13 steroids performed on a triple quadrupole (QqQ) MS/MS demonstrated that the performances obtained were in line with OECD recommendations. HRMS (MS1-HRMS) provided measurements nearly as sensitive and as reproducible as those obtained using multiple reaction monitoring (MRM) and ELISA. A bioinformatics workflow, using HRMS, was implemented to detect and annotate disrupted metabolites. HRMS allowed to detect disruptions in pathways associated to fatty acids, purines and amino acids metabolisms after exposure to the EDs tested, in addition to that linked to steroidogenesis. We developed a robust MS1-HRMS workflow, from sample preparation to compound quantification or annotation, compatible with absolute steroid quantification, to screen NCI-H295R cell media exposed to potential EDs. Using only 200μL of medium, the method integrates MS/MS and HRMS analyses, 96-well plate solid-phase extraction for high throughput, and automated pre-annotation for cost efficiency. This optimized workflow identifies EDs in cell assays by detecting disruptions in steroidogenesis and other biological pathways.

Identification and occurrence of microcystins in freshwaters and fish from a eutrophic dam through LC-HRMS.

Microcystins (MCs) are cyclic heptapeptides originating from various cyanobacteria in eutrophic aquatic environments. Their potential consequences on ecosystems and public health underscores the need to explore MCs' occurrence. In this study, liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) analysis and a suspect screening workflow supported by open-source tools were employed for the determination of MCs in freshwater and biota samples from a eutrophic dam in Uruguay. MS2 spectra were acquired using higher-energy collisional dissociation (HCD), data-dependent acquisition (DDA), and stepped NCE of [M+H]+ and [M+2H]2+ ions. In addition to the confirmation of 3 MCs in the samples, a comprehensive study of the acquired spectra led to the tentative identification of 30 MCs, including 2 partially described variants not previously reported. 33 MCs were determined in freshwaters, exhibiting a maximum MC concentration in a sample of 12731μg/L. Regarding fish, the 61% of the samples exhibited at least a positive determination. 8 MCs were detected and [D-Leu1]MC-LR, [seco-4/5]MC-LR, MC-LR, MC-RR, MC-WR, and [D-Asp3]MC-RR could be semi-quantified (3-127μg/kg, w.w). In 2 samples, the MC-LR content per 100g of fish was found to be close to 80% the tolerable daily intake for chronic exposure recommended by the WHO. The identification of [seco-4/5]MC-LR in biota highlights the labile byproducts of MCs and the need for wide-scope analytical approaches. This study emphasizes the extensive range of MCs present in eutrophic freshwater environments, their accumulation in exposed biota, and their potential entry into the food web.

Response and roles of algal organic matter under copper stress: Spectral and mass spectrometry analysis.

Eutrophication leads to various environmental issues, including pollution caused by the production of algal organic matter (AOM). Algae typically respond to environmental changes (e.g., light, temperature, copper [Cu(II)] concentration and pH) by regulating the production and release of different substances, thereby causing unpredictable effects on water quality. We explored the characteristics of AOM and the response mechanisms of algae under Cu(II) stress in the study, using fluorescence spectrum and high-resolution mass spectrometry (HRMS) analysis. The growth of Microcystis aeruginosa was inhibited under Cu(II) stress which was irreversible at Cu(II) concentration≥2μmol/L. Tryptophan- and humic-like fluorophores were important constituents of extracellular organic matter (EOM), and their contents increased with the addition of Cu(II), indicating that Cu(II) stimulates the production of tryptophan- and humic-like compounds. In addition, fulvic acid-like compounds in EOM were the main components binding to Cu(II) and were overproduced by algae under Cu(II) stress. It was found by HRMS at the molecular level that the formula numbers of EOM generally increased over inhibition time. Under 1μmol/L Cu(II) stress, nitrogenous compounds (CHON formulae) were the primary AOM, accounting for 37.3-52.0%. In addition, algae release a large amount of condensed aromatic structures to balance Cu(II) stress. This study provides a molecular-level analysis to explain the variation trends and response mechanisms of algae under various Cu(II) concentrations. The research methods are helpful for utilizing multiple advanced analysis methods to study algae growth and AOM release.

On the occurrence, behaviour, and fate of naphthenic acid fraction compounds in aquatic environments.

Naphthenic acids and naphthenic acid fraction compounds (NAFCs) are associated with production of unconventional petroleum resources, especially the Athabasca Oil Sands of Alberta, Canada. This complex mixture of acidic organic compounds is toxic to a variety of taxa, and so represents an important environmental management challenge. Thus, there is clear motivation to better understand the occurrence and characteristics of NAFCs in aquatic environments, their chemical behaviour, and environmental fate. Empowered by modern high-resolution mass spectrometry analyses, improved descriptions of the environmental occurrence of NAFCs have emerged. These studies include spatiotemporal survey studies describing the characteristics and quantities of NAFCs, as well as forensic methods working towards reliable source differentiations. Work has also proceeded in earnest to advance mechanistic understandings of how NAFCs are affected by passive phenomena, such as soil and sediment sorption, and chemically reactive mechanisms such as photolysis and biodegradation. Further advances describe the environmental fate and behaviour of NAFCs as they are transported and transformed across environmental compartments. In the context of Canadian oil sands, the available data describe NAFCs as a dynamic compound class that both affects and is affected by their receiving environment. By working towards a comprehensive understanding of the behaviour and fate of NAs and NAFCs, we might better anticipate the extent to which residual toxic effects may persist in reclaimed landscapes.

Synthesis of Novel Benzothiazole-Profen Hybrid Amides as Potential NSAID Candidates.

Herein, we report the synthesis of a series of new compounds by combining 2-aminobenzothiazole with various profens. The compounds were characterized using techniques such as 1H- and 13C-NMR, FT-IR spectrometry, and high-resolution mass spectrometry (HRMS), with detailed HRMS analysis conducted for each molecule. Their biological activities were tested in vitro, revealing significant anti-inflammatory and antioxidant effects, comparable to those of standard reference compounds. Lipophilicity was experimentally determined through partition coefficient (RM) measurements. To understand their binding affinity, molecular docking studies were perfsormed to analyze interactions with human serum albumin (HSA). The stability of these predicted complexes was further evaluated through molecular dynamics simulations. The results highlight the compounds' promising biological activity and strong affinity for HSA. The new hybrid molecule between 2-ABT and ketoprofen 3b demonstrates significant promise based on the experimental data and is further supported by in silico calculations. Compound 3b exhibits the best hydrogen peroxide scavenging activity among the tested compounds, with an IC50 of 60.24 μg/mL. Furthermore, 3b also displays superior anti-inflammatory activity, with an IC50 of 54.64 μg/mL, making it more effective than the standard ibuprofen (76.05 μg/mL).

Profiling and Antibacterial Activity Assay of Secondary Metabolites from Streptomyces Isolated from Mangrove Sediment Sample

Bacterial infections pose significant threats to human health, particularly due to the rise of antibiotic-resistant strains. Identifying new sources of effective antibiotics is therefore crucial for combating these resistant pathogens. This study aims to isolate novel Streptomyces species and profile their secondary metabolites through extraction and high-resolution mass spectrometry (HRMS) analysis. Furthermore, the antibacterial activity of the extract containing the secondary metabolites was assessed through the in vitro agar well diffusion method and supported by the molecular docking, molecular dynamics simulations, and drug-likeness analysis. Sediment samples were collected from mangrove forests in Yogyakarta. The bacteria were then isolated, purified, and characterized using 16S rRNA sequencing. The isolates were then cultured to enrich the secondary metabolites, and their secondary metabolites were extracted using methanol and dichloromethane solvents in a 1:1 volume ratio. The results showed that the isolated bacteria of Streptomyces sp. were obtained with a 95.44% similarity rate, which produced several secondary metabolites. The in vitro antibacterial assay of the extract resulted in an inhibition zone of 14, 14, and 15 mm against Propionibacterium acnes, Staphylococcus aureus, and Escherichia coli, respectively. The molecular docking and molecular dynamic simulations for 100 ns revealed that compound SB236057A could inhibit the function of thymidylate kinase protein through a carbon-hydrogen bond with Glu37 residue. Furthermore, drug-likeness analysis showed that the secondary metabolites of Streptomyces sp. exhibited preferable drug-likeness and pharmacokinetic properties. This research focuses on the understanding of microbial biodiversity in mangrove sediments, particularly focusing on the genus Streptomyces and its potential to produce novel antibiotics.

Rounded Turn SLIM Design for High-Resolution Ion Mobility Mass Spectrometry Analysis of Small Molecules.

Various rounded turn designs in Structures for Lossless Ion Manipulation (SLIM) were explored via ion trajectory simulations. The optimized design was integrated into a SLIM ion mobility (IM) system coupled with a time-of-flight (TOF) mass spectrometer (MS) for further experimental investigation. The SLIM-TOF IM-MS system was assessed for IM resolution and ion transmission efficiency across a wide m/z range using various RF frequencies and buffer gas combinations. High ion transmission efficiency and high resolution ion mobility (HRIM) separation were achieved for Agilent tune mix ions through a ∼12.8 m serpentine separation path in both nitrogen and helium. In helium, ion transmission for low m/z ions was enhanced at higher RF trapping frequency, enabling the detection of ions with m/z below 50 and all 17 amino acids from a standard mixture. Lossless ion transmission was observed for glycine (m/z 76) in both passthrough and HRIM modes. HRIM resolution was benchmarked using L-isoleucine, L-leucine, and various other isobaric and isomeric metabolites with m/z values of 60-89. This work demonstrates a rounded turn SLIM design that enables HRIM measurements for small molecule analytes, with a particular focus on metabolomics, where IM offers a means to enhance the speed, robustness, and specificity of analytical workflows.

A comprehensive approach to characterizing bioactive compounds from Haplanthodes tentaculatus (L.) R. B. Majumdar using HR-LCMS and MTT assay

The bioactive compounds in Haplanthodes tentaculatus (L.) R. B. Majumdar has demonstrated significant potential in addressing conditions like cancer, diabetes, inflammation, and microbial infections. This study employs high-resolution liquid chromatography mass spectrometry and network analysis to investigate these chemicals. The methanolic extract revealed 92 identified compounds, many of which exhibited inhibitory effects on MDA-MB-231 breast cancer cell growth. Aclacinomycin N, Ganoderic acid Mb, Cucurbitacin E, and Hydroquinidine displayed notable inhibitory effects. The extract demonstrated an IC50 value of 61.41±0.692 μg, showcasing its effectiveness in impeding cancer cell development. While promising, further research is needed to unravel the specific molecular pathways involved. The identification and characterization of distinct chemicals in the extract offer potential leads for medication development. This work underscores H. tentaculatus as a vital source of bioactive substances with potent anticancer properties, emphasizing the need for continued exploration in advancing cancer therapies.

Dispersive solid phase extraction of 18 PFAS from environmental water samples using a novel MOF-polymeric monolith composite followed by High-Resolution mass spectrometry analysis

Metal-organic frameworks (MOFs) have been broadly coupled with many pretreatment techniques due to their remarkable attributes including high porosity, significantly increased specific surface area, and chemical stability, but their nanoscale dimensions make their handling challenging. To overcome this, a novel MOF-polymeric monolith composite was synthesized and studied as a novel sorbent material in an analytical technique. A rapid and efficient method for the extraction of a mixture of 18 per- and poly-fluoroalkyl (PFAS) compounds from environmental water samples was established based on MOF-polymeric monolith composite assisted dispersive solid phase extraction (d-SPE). The analytical methodology was carried out with the aid of liquid chromatography tandem high-resolution mass spectrometry. Several parameters influencing the extraction efficiency were comprehensively evaluated and optimized. The optimization was based on two processes: the one-variable-at-a-time approach (OVAT) and the central composite design (CCD). Preliminary studies were conducted and the extraction and elution time, as well as the sample volume were evaluated by adopting OVAT approach. The optimal parameters were found to be 15 min for extraction time, 5 min for the elution time and 10 mL as sample volume. Under the optimum conditions, the sample pH, sorbent amount and eluent volume were all evaluated under the design of experiments (DoE). ANOVA demonstrated the suitability of the suggested model with a p-value of less than 0.05 and various diagnostic tests validate the well-fitting results. The software extracted the optimal conditions which were pH = 7, sorbent amount = 10 mg and eluent volume = 750 μL. The method was subsequently validated with respect to accuracy, linearity detection limits and reproducibility. The proposed method presented recoveries over 70 %, method detection limits 1–46 ng/L and relative standard deviations <20 %. Before the implementation of the method in real samples, the “green” character was evaluated using the ComplexGAPI index, indicating the satisfactorily “green” character of the new MOF-based dSPE-LC-HRMS method. Finally, the efficacy of the method for determining PFASs in four environmental water matrices was tested using several matrices of varying complexity, including wastewater effluent, river water, marine water, and runoff.

Discovery of nostatin A, an azole-containing proteusin with prominent cytostatic and pro-apoptotic activity.

Ribosomally synthesized and post-translationally modified peptides (RiPPs) are intriguing compounds with potential pharmacological applications. While many RiPPs are known as antimicrobial agents, a limited number of RiPPs with anti-proliferative effects in cancer cells are available. Here we report the discovery of nostatin A (NosA), a highly modified RiPP belonging among nitrile hydratase-like leader peptide RiPPs (proteusins), isolated from a terrestrial cyanobacterium Nostoc sp. Its structure was established based on the core peptide sequence encoded in the biosynthetic gene cluster recovered from the producing strain and subsequent detailed nuclear magnetic resonance and high-resolution mass spectrometry analyses. NosA, composed of a 30 amino-acid peptide core, features a unique combination of moieties previously not reported in RiPPs: the simultaneous presence of oxazole/thiazole heterocycles, dehydrobutyrine/dehydroalanine residues, and a sactionine bond. NosA includes an isobutyl-modified proline residue, highly unusual in natural products. NosA inhibits proliferation of multiple cancer cell lines at low nanomolar concentration while showing no hemolysis. It induces cell cycle arrest in S-phase followed by mitochondrial apoptosis employing a mechanism different from known tubulin binding and DNA damaging compounds. NosA also inhibits Staphylococcus strains while it exhibits no effect in other tested bacteria or yeasts. Due to its novel structure and selective bioactivity, NosA represents an excellent candidate for combinatorial chemistry approaches leading to development of novel NosA-based lead compounds.

Highly Potent Fluorenone Azine-based ESIPT Active Fluorophores for Cellular Viscosity Detection and Bioimaging Applications.

Herein, synthesizes of fluorenone azine-based Schiff fluorescence probes: (E)-2-(((9H-fluoren-9-ylidene)hydrazineylidene)methyl)-5-(diethylamino)phenol (3a), (E)-9-(((9H-fluoren-9-ylidene)hydrazineylidene) methyl)-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-8-ol (3b), and (E)-1-(((9H-fluoren-9-ylidene)hydrazineylidene)methyl) naphthalen-2-ol (3c). The probes were structurally characterized using Fourier-transform infrared spectroscopy (FTIR), 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry(HRMS) analysis. The probes exhibit hydrogen bonding between phenolic -OH and imine nitrogen, enabling excited state intramolecular proton transfer (ESIPT) and free rotation in the azine (> C = N-N = C <) functional, facilitating twisted intramolecular charge transfer (TICT), and a positive solvatochromism in solvent-dependent emission studies. Further, density functional theory (DFT) based calculations accounted for the observed photophysical TICT and ESIPT processes, revealing a non-covalent interaction between phenolic -OH and imine nitrogen. Furthermore, the fluorescence intensity (log I) showed good linearity (R2 = 0.999) with the viscosity (log η) with Förster-Hoffmann coefficient (X) values of 2.238, 1.405 and 3.121 for 3a, 3b and 3c, respectively. The study established the probes toxicity and fluorescence imaging in the Caenorhabditis elegans model. Probe 3a, the first azine-based probe for micro viscosity detection, demonstrated exceptional efficacy in detecting intercellular viscosity and facilitating bioimaging applications.

Photochemistry of microplastics-derived dissolved organic matter: Reactive species generation and organic pollutant degradation

Dissolved organic matter (DOM) originating from microplastics (MPs-DOM) is increasingly recognized as a substantial component of aquatic DOM. The photochemistry of MPs-DOM, essential for understanding its environmental fate and impacts, remains largely unexplored. This study investigates the photochemical behaviors of MPs-DOM derived from two common plastics: polystyrene (PS) and polyvinyl chloride (PVC), which represent aromatic and aliphatic plastics, respectively. Spectral and high-resolution mass spectrometry analyses demonstrated that photoreactions preferentially targeted poly-aromatic compounds within the MPs-DOM, leading to degradation products that predominantly form N-aliphatic/lipid-like substances. This transformation is characterized by decreased aromaticity and unsaturation. Additionally, irradiation of MPs-DOM generated reactive species (RS), including triplet intermediates (3DOM*) and singlet oxygen (1O2), with apparent quantum yields of 0.06–0.16 % and 0.16–0.35 %, respectively—values considerably lower than those for conventional DOM (1.19–1.56 % for 3DOM* and 1.34–1.90 % for 1O2). Despite this, the RS generated from MPs-DOM significantly enhance the degradation of coexisting organic pollutants, such as antibiotic resistance genes (ARGs). The findings shed light on the photoinduced transformation of MPs-DOM and suggest that MPs-DOM functions as a natural photocatalyst, mediating redox reactions of pollutants in sunlit aquatic settings. This highlights its previously underestimated role in natural attenuation and aquatic photochemistry.

Synthesis and Antifungal Activity Evaluation of Novel L-Carvone-Based 1,3,4-Thiadiazole-amide Derivatives as a Potential Succinate Dehydrogenase Inhibitor.

In an effort to explore new-type high-efficiency antifungal agents, 25 novel L-carvone-based 1,3,4-thiadiazole-amide derivatives were designed, synthesized, and structurally characterized by IR, 1H NMR, 13C NMR, and high-resolution mass spectrometry (HRMS) analyses. The antifungal activity of the target compounds was preliminarily assayed at a concentration of 50 μg/mL, and boscalid, a commercialized fungicide identified as a succinate dehydrogenase inhibitor (SDHI), was employed as the positive control. It was found that all of the target compounds showed moderate to potent antifungal activity against the tested fungi compared to boscalid. Surprisingly, compound 4b exhibited broad-spectrum and significant inhibition activity against the growth of eight phytopathogenic strains with inhibitory rates of 67-89%. Further, the results of the EC50 value test suggested that the EC50 values of compound 4b against Physalospora piricola and Colletotrichum orbiculare were 16.33 and 18.06 μg/mL, respectively, and both of them were better than those of boscalid (16.64 and >50). Therefore, compound 4b deserves further study as a lead compound for novel fungicides. In addition, the inhibitory activity of compound 4b against succinate dehydrogenase (SDH) was evaluated as well to prove that compound 4b (IC50 = 3.38 μM) displayed higher SDH-inhibition activity than boscalid (IC50 = 7.02 μM). The binding mode of compound 4b and SDH was simulated by molecular docking and found to be similar to that of boscalid. The structure-activity relationships (SARs) of the target compounds were analyzed by establishing a 3D-QSAR model. Besides, a 4b-loaded complex 4b/CSTA on a reported L-carvone-based nanochitosan carrier CSTA containing the 1,3,4-thiadiazole-amide group was constructed, and its sustained release performance was investigated in the EtOH-H2O system (1:9, v/v). The complex 4b/CSTA exhibited preferred sustained release performance, indicating its potential for developing environmentally friendly nanofungicides.

Naturally Occurring Flavonol, Quercetagetin 5,6,7,3',4'-Pentamethyl Ether (Marionol), as a Nontoxic Plant-Based Fluorescent Probe for Rapid, Sensitive, and Selective Detection of Cu2+ in Water.

Herein, we report a naturally occurring flavonol, quercetagetin 5,6,7,3',4'-pentamethyl ether (known as marionol), as a nontoxic fluorescent probe for rapid, sensitive, and selective detection of Cu2+ in water. The interaction between marionol and Cu2+ ions is studied by various state-of-the-art spectroscopic techniques such as 1H NMR, UV-vis, fluorescence, and high-resolution mass spectrometry (HRMS). Marionol shows strong fluorescence quenching in the presence of Cu2+, whereas other interfering cations such as Fe3+, Co2+, Al3+, Pb2+, Hg2+, Zn2+, Mg2+, Mn2+, Ca2+, Cu+, Ag+, Na+, and K+ produce negligible changes in fluorescence. The binding stoichiometry between marionol and Cu2+ is found to be 2:1, according to Job's plot and HRMS analyses. The binding constant (K a) of Cu2+ with marionol is calculated to be 2.89 × 109 M-2, and the limit of detection is found to be 0.15 μM. In addition, marionol is further used for the quantification of Cu2+ in natural spring water samples. The good recoveries (92-110% with RSD <5%) and its low toxicity to MCF-7 human breast cancer cells make marionol a unique plant-based fluorescent probe for the detection of Cu2+ ions.

Talaketides A−G, linear polyketides with prostate cancer cytotoxic activity from the mangrove sediment-derived fungus Talaromyces sp. SCSIO 41027

Seven novel linear polyketides, talaketides A−G (1−7), were isolated from the rice media cultures of the mangrove sediment-derived fungus Talaromyces sp. SCSIO 41027. Among these, talaketides A−E (1−5) represented unprecedented unsaturated linear polyketides with an epoxy ring structure. The structures, including absolute configurations of these compounds, were elucidated through detailed analyses of nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HR-MS) data, as well as electronic custom distributors (ECD) calculations. In the cytotoxicity screening against prostate cancer cell lines, talaketide E (5) demonstrated a dose-dependent inhibitory effect on prostate cancer PC-3 cell lines, with an IC50 value of 14.44 μmol·L−1 . Moreover, compound 5 significantly inhibited the cloning formation of PC-3 cell lines and arrested the cell cycle in S-phase, ultimately inducing apoptosis. These findings indicate that compound 5 may serve as a promising lead compound for the development of a potential treatment for prostate cancer.

Synthesis and biological evaluation of diclofenac acid derivatives as potential lipoxygenase and α-glucosidase inhibitors.

Inflammation is a complex physiological response associated with the onset and progression of various disorders, including diabetes. In this study, we synthesized a series of diclofenac acid derivatives and evaluated their potential anti-diabetic and anti-inflammatory activities. The compounds were specifically assessed for their ability to inhibit 15-lipoxygenase (15-LOX) and α-glucosidase enzymes. The structures of synthesized derivatives were confirmed through 1H nuclear magnetic resonance (NMR), 13C-NMR and high-resolution mass spectrometry (electron ionization) analysis. All these synthesized derivatives exhibited varying degrees of inhibitory activity against LOX, when compared with standard drugs, compounds 5a (half-maximal inhibitory concentration (IC50) 14 ± 1 µM), 5b (IC50 61 ± 1 µM) and 7c (IC50 67 ± 1 µM) showed good activity against the LOX enzyme. While the α-glucosidase inhibitory results revealed that most of the compounds exhibited significant activity when compared with the standard drug acarbose (376 ± 1 µM). The most potent compounds as α-glucosidase inhibitors were 7b (3 ± 1 µM), 4b (5 ± 1 µM), 7a (7 ± 1 µM) and 8b (11 ± 1 µM). All these active compounds were found to be least toxic and maintained the mononuclear cells viability at 96-97% compared with that of controls as determined by multi-transaction translator assay. Molecular docking studies further reiterated the significance of these 'lead' compounds with great potential against the target enzymes in the process of drug discovery.

Deciphering the key drivers of oxidative potential during ammonium nitrate-mediated aqueous-phase photoreaction of methoxyphenols

Methoxyphenols are released in abundance from lignin pyrolysis during biomass burning. Apart from being atmospheric brown carbon components that absorb solar radiation and warm the climate, methoxyphenols also undergo photoreaction in the atmospheric aqueous phase and form secondary organic aerosols (aqSOA). While efforts have been devoted to understanding chemical evolutions and climate-related optical properties of aqSOA, their potential health impacts also require timely investigations. Herein, we used the dithiothreitol (DTT) assay to investigate oxidative potential of the aqSOA formed during the 8-h aqueous-phase photoreaction of two typical methoxyphenols, vanillin and vanillic acid, under pH 2 or 8, and with or without ammonia nitrate. The highest DTT consumption rates (RDTT) were observed for vanillin aqSOA formed in the presence of ammonia nitrate and at pH 8. At pH 2, although RDTT increased rapidly during early photoreaction, it reduced after prolonged illumination. High-resolution mass spectrometry and linear regression analyses were performed to correlate the photoreaction products with the observed RDTT. Results showed that three products that present quinone, lactone and dimer structures, respectively, should be the key drivers of elevated RDTT for aqSOA formed during photoreaction of vanillin and vanillic acid alone, whereas it shifted to the nitrogen-containing aromatic compounds during their photoreaction with ammonia nitrate. Our results have revealed the role of nitrogen-containing aromatic compounds in the oxidative potential and health effects of aqSOA from biomass burning, which was rarely recognized before and warrants immediate assessments.

Administration Route Differentiation of Altrenogest via the Metabolomic LC-HRMS Analysis of Equine Urine.

Altrenogest, also known as allyltrenbolone, is a synthetic form of progesterone used therapeutically to suppress unwanted symptoms of estrus in female horses. Altrenogest affects the system by decreasing levels of endogenous gonadotrophin and luteinizing and follicle-stimulating hormones, which in turn decreases estrogen and mimics the increase of progesterone production. This results in more manageable mares for training and competition alongside male horses while improving the workplace safety of riders and handlers. However, when altrenogest is administered, prohibited steroid impurities such as trendione, trenbolone, and epitrenbolone can be detected. It has been assumed that greater concentrations of these steroid impurities are present in injectable preparations and, therefore, pose a greater risk of causing anabolic effects when administered. For this reason, and due to the necessity of this therapeutic substance for the safety of thoroughbred racing participants, a metabolomic approach investigating the differentiation of two main administration routes was conducted. Liquid chromatography high-resolution mass spectrometry analysis of equine urine samples found five sulfated compounds, estrone sulfate, testosterone sulfate, 2-methoxyestradiol sulfate, pregnenolone sulfate, and cortisol sulfate, with the potential to differentiate between oral and intramuscularly administered altrenogest using a random forest classification model. The best model results, comparing two horses' administration normalized peak area datasets, gave an AUC score of 0.965 with a confidence level of 95% (between 0.931 and 0.995). Identifications of these compounds were confirmed with assistance from the Shimadzu Insight Explore Assign feature, together with MS/MS spectrum and retention time matching of purchased and synthesized reference standards. This study proposes a new potential application for metabolomic multi-tool workflows and machine learning models in a forensic toxicological context.

LC-HRMS-based global metabolomics profiling unravels the distinct metabolic signature of lapatinib-resistant and trastuzumab-resistant HER2+ breast cancer cells

The effectiveness of lapatinib (LAP) and trastuzumab (TRZ), the first-line therapies for HER2+ breast cancer, has been limited owing to the development of acquired resistance in patients with HER2+. This study aimed to investigate the alterations in metabolic signatures in LAP-resistant HCC1954 and TRZ-resistant HCC1954 and pathways in human HER2+ breast cancer cells using liquid chromatography–high-resolution mass spectrometry (LC-HRMS) and enrichment analysis. The HCC1954 parental cells were sequentially treated 13 rounds with LAP or TRZ to develop resistant cells and then tested for their cytotoxicity using the MTT assay. Metabolites were prepared from HCC1954 parental (MBXWT), HCC1954-LAP (MBXLAP), and HCC1954-TRZ (MBXTRZ) cells prior to LC-HRMS, chemometric, enrichment, and joint pathway analyses. LAP- and TRZ-resistant cells were successfully developed from HCC1954, and 29 and 17 differentially expressed metabolites (DEMs) were identified between MBXWT-MBXLAP and MBXWT-MBXTRZ, respectively. The analysis of DEMs between MBXWT and MBXLAP revealed significant enrichment in D-amino acid metabolism, while MBXWT and MBXTRZ identified valine, leucine, isoleucine biosynthesis, ascorbate, and aldarate metabolism. Joint pathway enrichment analysis of LAP-resistant DEMs and differentially expressed genes (DEGs) showed enrichment in glutathione metabolism, while that of TRZ-resistance and DEGs showed enrichment in carbohydrate metabolism, namely pentose and glucuronate interconversions, starch and sucrose metabolism, and galactose metabolism. The findings from this study indicate considerable metabolic changes in LAP- and TRZ-resistant HCC1954 cells, which are crucial for understanding the resistance mechanisms and developing strategies to overcome these problems.

Molecular Insights into Gas-Particle Partitioning and Viscosity of Atmospheric Brown Carbon.

Biomass burning organic aerosol (BBOA), containing brown carbon chromophores, plays a critical role in atmospheric chemistry and climate forcing. However, the effects of evaporation on BBOA volatility and viscosity under different environmental conditions remain poorly understood. This study focuses on the molecular characterization of laboratory-generated BBOA proxies from wood pyrolysis emissions. The initial mixture, "pyrolysis oil (PO1)", was progressively evaporated to produce more concentrated mixtures (PO1.33, PO2, and PO3) with volume reduction factors of 1.33, 2, and 3, respectively. Chemical speciation and volatility were investigated using temperature-programmed desorption combined with direct analysis in real-time ionization and high-resolution mass spectrometry (TPD-DART-HRMS). This novel approach quantified saturation vapor pressures and enthalpies of individual species, enabling the construction of volatility basis set distributions and the quantification of gas-particle partitioning. Viscosity estimates, validated by poke-flow experiments, showed a significant increase with evaporation, slowing particle-phase diffusion and extending equilibration times. These findings suggest that highly viscous tar ball particles in aged biomass burning emissions form as semivolatile components evaporate. The study highlights the importance of evaporation processes in shaping BBOA properties, underscoring the need to incorporate these factors into atmospheric models for better predictions of BBOA aging and its environmental impact.