High-resolution Mass Spectrometry Research Articles

Broad Microbial Community Functions in a Conventional Activated Sludge System Exhibit Temporal Stability.

Wastewater microbial communities within conventional activated sludge (CAS) systems can perform hundreds of biotransformations whose relative importance, frequency, and temporal stability remain largely unexplored. To improve our understanding of biotransformations in CAS systems, we collected 24 h composite samples from the influent and effluent of a CAS system over 14 days, analyzed samples using high-resolution mass spectrometry (HRMS), and conducted a nontarget analysis of our HRMS acquisitions. We found that over 50% of the chemical features in the influent were completely removed, and the daily number of detected features exhibited low variability with a coefficient of variation of 0.07. Additionally, we found 352 Core chemical features present in every sample at both locations. We used chemical features to search for evidence of 19 potential biotransformations and detected 9 of these biotransformations at a frequency of over 80 times per day, where evidence for dehydrogenations, hydroxylations, and acetylations was most frequently detected. The daily number of detections for the 9 biotransformations exhibited coefficients of variation ranging from 0.13-0.20, revealing the broad temporal stability for these wastewater microbial community functions. This stability contrasts with the previously observed temporal variability for micropollutant biotransformations, suggesting that micropollutant biotransformations are linked to specialized microbial community functions.

Identifying Organic Chemicals with Acetylcholinesterase Inhibition in Nationwide Estuarine Waters by Machine Learning-Assisted Mass Spectrometric Screening.

Neurotoxicity is frequently observed in the global aquatic environment, threatening aquatic ecosystems and human health. However, a very limited proportion of neurotoxic effects (∼1%) has been explained by known chemicals of concern. Here, we integrated machine learning, nontargeted analysis, and in vitro biotesting to identify neurotoxic drivers of acetylcholinesterase (AChE) inhibition in estuarine waters along the coast of China. Machine learning was used to predict AChE inhibitors in a large chemical space. The prediction output was profiled into a suspect screening list to guide high-resolution mass spectrometry (HRMS) screening of AChE inhibitors in estuarine water samples. Ultimately, 60 chemicals with diverse known and presently unknown structures were identified, explaining 82.1% of the observed AChE inhibition. Polyunsaturated fatty acids were unexpectedly found to be neurotoxic drivers, accounting for 80.5% of the overall effect. This proof-of-concept study demonstrates that machine learning-based toxicological prediction can achieve a virtual fractionation role to pinpoint HRMS features with the bioactivity potential. Our approach is expected to enable rapid and comprehensive screening of organic pollutants associated with various in vitro end points for large-scale monitoring of water quality.

Sn-Position-Resolved Quantification of Aminophospholipids by Isotopic N,N-Dimethyl Leucine Labeling and High-Resolution Ion Mobility Mass Spectrometry.

Aminophospholipids (APLs), composed of phosphatidylethanolamines (PEs) and phosphatidylserines (PSs), are vital components of mammalian cell membranes and lipoproteins, participating in both homeostasis and cellular signaling. Their structural changes, including the permutation of fatty acid connectivity (sn-positions), due to dysfunctional metabolic processes have been linked to many diseases. However, the accurate quantification of APLs with unambiguous fatty acyl assignment through routine label-free LC-MS/MS lipidomic analysis remains a major challenge. In this study, we explore the functionalization of the free primary amine groups of APLs using amine-reactive isotopic N,N-dimethyl leucine (iDiLeu) and employ high-resolution ion mobility MS (IM-MS) to develop a novel method for sensitive discernment and accurate quantification of APL sn-isomers. With high-resolution demultiplexing (HRdm) providing IM resolving power >200, labeled sn-isomeric pairs of APLs (ΔCCS ≈ 1%) demonstrate excellent, near baseline separation. In addition to greatly enhanced sensitivity, 5-plex iDiLeu labeling enables the construction of an internal 4-point calibration curve and therefore absolute quantification of APL sn-isomers in a single run. This strategy enabled precise annotation and quantification of 239 APLs including 60 pairs of sn-isomers in the mouse cortex. Additionally, we were able to find ratio changes in multiple APL sn-isomer pairs between wild type and APP/PS1 Alzheimer's disease (AD) model mice at different ages, indicating their strong correlation to AD progression. This strategy could provide universal utility in unraveling the alteration of APL sn-isomers, which have long been considered as the "dark matter" of traditional lipidomic analyses, leading to more precise elucidation of molecular mechanisms of various diseases.

Design, synthesis, X-ray crystal structure, and antifungal evaluation of new acetohydrazide derivatives containing a 4-thioquinazoline moiety.

To find efficient agricultural fungicides, 29 new 4-thioquinazoline-containing acetohydrazide derivatives were prepared and tested for their fungicidal properties. All of the target compounds were characterized by 1H and 13C nuclear magnetic resonance and high-resolution mass spectrometry techniques, and the molecular structure of compound A2 was verified by single-crystal X-ray diffraction measurement. The experimental results revealed that many compounds from this series had impressive inhibition efficacies in vitro against the tested fungi. For example, compound A25 was identified as the best fungicidal agent against Rhizoctonia solani with an EC50 (half-maximal effective concentration) value of 0.66 μg mL-1, superior to those of the commercial fungicides chlorothalonil, carbendazim and boscalid. Additionally, this compound displayed favorable protection and curative activities in vivo against rice sheath blight caused by R. solani. Antifungal mechanistic studies on compound A25 indicated that this compound exerted its strong anti-R. solani effects probably through an effective inhibition of fungal succinate dehydrogenase activity [half-maximal inhibitory concentration (IC50) = 4.88 μm] and the impairment of cell membrane integrity, based on the results from enzymatic bioassays, molecular docking studies, and scanning and transmission electron microscopy observations. Acetohydrazide derivatives containing the 4-thioquinazoline moiety had the potential to be employed as lead compounds for developing more efficient agricultural fungicides in the near future. © 2024 Society of Chemical Industry.

Bioaccessibility of Cafestol from Coffee Brew: A Metabolic Study Employing an In Vitro Digestion Model and LC-HRMS.

Cafestol is an ent-kaurene skeleton diterpene that is present in coffee beans and brews. Although several biological activities have been described in the literature for cafestol, such as hypercholesterolemic, anti-inflammatory, anticerous, and antidiabetic effects, its metabolism within the human body remains poorly understood. Therefore, this study aimed to quantify cafestol in boiled coffee brew, assess its bioaccessibility using a static in vitro digestion model, and investigate the metabolites formed during the digestion process using liquid chromatography coupled to high-resolution mass spectrometry. Cafestol content in the boiled coffee brew ranged from 127.47 to 132.65 mg L-1. The bioaccessibility of cafestol from boiled coffee brew using the in vitro digestion model was 93.65%; additionally, in the intestinal phase, cafestol was mainly found in its alcohol form. Additionally, a novel carboxylic acid derivative metabolite from cafestol with m/z 331.1909 [M + H]+ formed in the oral digestion phase is proposed. This metabolite was also detected in other digestion phases. Thus, this is the first article to investigate the metabolism of cafestol during digestion using an in vitro digestion model. The results indicate that cafestol is bioaccessible, is available to absorption, in its alcohol form, and suffers an oxidation reaction during the oral phase of digestion.

Structure Elucidation of the Daptomycin Products Generated upon Heterologous Expression of the Daptomycin Resistance Gene Cluster drcAB.

Recently, a high-level daptomycin (DAP)-resistant Mammaliicoccus sciuri strain (TS92) was identified, which mediates a 33% decline of DAP when incubated in Mueller-Hinton (MH) medium. The genetic background of the DAP resistance in TS92 is a newly discovered two-gene operon, named drcAB, whose expression was reported to impair the structural integrity of DAP, eventually leading to its inactivation. Here, we set out to elucidate the chemical nature of drcAB-mediated DAP modification by applying a general unknown comparative screening (GUCS) approach in high-resolution mass spectrometry. DAP in MH medium was incubated with Staphylococcus aureus strain RN4220_Pxyl/tet-drcAB, which carries the drcAB operon under control of an inducible promoter on a plasmid, and GUCS test and reference samples were obtained upon and without drcAB expression. A two-step process catalyzed by DrcAB was discovered, comprising a structural alteration of DAP. The mass spectrometric data indicate an N-substitution at the aniline moiety of kynurenine with dehydroalanine and, subsequently, a cleavage of the ester bond of the DAP core between kynurenine and threonine by means of water. The structures postulated were confirmed by comparison of in silico versus measured fragmentation patterns.

Changes in the small-molecule fingerprints of rice planted near an industrial explosion site in Taiwan.

A fire and explosion accident at a petrochemical complex sparked concerns over the rice health and production in nearby paddy fields. To unveil the potential effects, this study investigated small molecule changes in rice harvested in nearby counties using non-target analysis. Rice grains were harvested three, eight, 15, and 20months after the accident from a total of ten townships. Small-molecule (m/z 70-1100) data in brown rice (n = 27) were acquired using high-resolution mass spectrometry (HRMS). Partial least squares discriminant analysis (PLS-DA) models were constructed to illustrate the temporal and spatial trends of rice's small-molecule fingerprints, and markers of production locations were identified. The small-molecule fingerprint in the rice directly exposed to the accident and harvested three months after the explosion differed significantly from those planted after the accident (PLS-DA model Q2 = 0.943, Q2/R2Y = 0.962), probably indicating the exclusion of long-term effects. Besides, in the rice directly exposed to the accident, the rice collected from near the explosion site (< 15km) exhibited reduced jasmonic acid and increased imidacloprid levels (log2 fold change: -1.53 and 5.46, respectively), compared to that from farther locations. The result would suggest compromised disease defence in rice grown under the stress of explosion. In addition, lipid and amino acid metabolism perturbations are deemed relevant to plant development.

Quantitative analysis of cannabinoids and metabolites in oral fluid by volumetric absorptive microsampling combined with UHPLC-HRMS.

With recent evolution of cannabis legalization around the world and multiplication of cannabis derived products, identifying and qualifying cannabis consumption has a proven interest. Although blood, plasma, and urine are common matrices widely used in toxicology laboratories, oral fluid presents specific advantages. In the context of doping tests, addiction consultation or roadside checks, where other matrices are impractical to collect or can be adulterated, oral fluid is a promising matrix that allows a non-invasive, rapid, and monitored self-sampling. However, available devices required a consequent volume of oral fluid,more than 250 µL, sometimes difficult to collect. We present here a fully optimized quantitative method for seven cannabinoids, including four metabolites, in oral fluid, Δ9-tetrahydrocannabinol, 11-hydroxy-Δ9-tetrahydrocannabinol and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol; cannabidiol, 7-hydroxy and 7-carboxycannabidiol; and cannabinol. After self-collection of 20 µL using an accurate and precise volumetric absorptive microsampling device (VAMS®), cannabinoids were derivatized with 2-fluoro-1-methylpyridinium p-toluenesulfonate to increase sensitivity. The successive steps of the proposed method, including biosampling, 1 h sample preparation with derivatization, and acquisition by ultrahigh-performance liquid chromatography coupled to high-resolution mass spectrometry, were fully optimized. A limit of quantification of 0.5 ng/mL (≈10 pg per sampling) was thus targeted, adapted to the legal threshold required by the authorities and to clinical monitoring. Applied to six cannabis consumers, the proposed method made it possible to quantify in 20 µL oral fluid samples, Δ9-tetrahydrocannabinol ranging from 0.5 to 6236 ng/mL, cannabidiol from 0.6 to 190 ng/mL and cannabinol from 0.5 to 118 ng/mL.

Global Identification of Anti-Melanoma Cellular Targets by Photochemically Induced Coupling of L-Shikonin Reactions on the Surface of Magnetic Particles

Background: L-Shikonin, an active component of Arnebia euchroma (Royle) Johnst., has remarkable pharmacological effects, particularly in its anti-tumour activity. Nonetheless, the specific targets and mechanisms of action remain to be further explored. Methods: A novel Fe3O4@L-Shikonin was designed and synthesized in this study by linking Fe3O4 and L-Shikonin through benzophenone. Fe3O4@L-Shikonin was characterized using several techniques, including scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and drug removal methods, to determine the content of L-Shikonin on the surface of the magnetic particles. Target hooking technology was utilized to identify the target proteins of the compound in melanoma. The synthesized Fe3O4@L-Shikonin was co-incubated with A375 cell lysate, followed by the target proteins, which were purified by magnetic enrichment using magnetic microspheres and identified by high-resolution mass spectrometry. Results: AutoDock Vina software was employed for molecular docking analysis, where it was found that L-Shikonin targets RPN1, CPEB4, and HNRNPUL1 proteins. Subsequently, A375 cells were treated with L-Shikonin at different concentrations (2.5, 5.0, 10.0 μM) for 48 h, and the expressions of the three proteins were observed. The results showed a significant reduction in the relative expression of CPEB4 in the high-dose group compared to the control group (p &lt; 0.01). Moreover, the relative expression of HNRNPUL1 was decreased in the medium- and high-dose groups (p &lt; 0.05). Conclusions: This study initially revealed from the source that L-Shikonin may regulate melanoma-specific markers, melanosomes, tyrosine kinases related to abnormal tyrosine metabolism, and melanoma through multiple targets such as CPEB4 and HNRNPUL1. Proliferation and metastasis work together to exert an anti-melanoma mechanism, which provides a new idea for the follow-up study of the molecular pharmacological mechanism of the complex system of total naphthoquinones in Arnebia euchroma (Royle) Johns.

Mass Spectrometry Imaging Reveals Spatial Metabolic Alterations and Salidroside’s Effects in Diabetic Encephalopathy

Background: Diabetic encephalopathy (DE) is a neurological complication of diabetes marked by cognitive decline and complex metabolic disturbances. Salidroside (SAL), a natural compound with antioxidant and neuroprotective properties, has shown promise in alleviating diabetic complications. Exploring the spatial metabolic reprogramming in DE and elucidating SAL’s metabolic effects are critical for deepening our understanding of its pathogenesis and developing effective therapeutic strategies. Methods: Air-flow-assisted desorption electrospray ionization–mass spectrometry imaging (AFADESI-MSI) was employed to investigate spatial metabolic alterations in the brains of db/db mice, a spontaneous DE model. The mice were treated with SAL (30 and 150 mg/kg, orally) for 12 weeks. Differential metabolites were identified and characterized using high-resolution mass spectrometry and validated against public databases. Results: Our AFADESI-MSI analysis revealed significant changes in 26 metabolites in the brains of DE mice compared to the controls. These metabolic changes indicated disruptions in glucose, glutamate-glutamine, nucleotide, lipid, choline, aspartate, and L-carnitine metabolism. Notably, glucose 6-phosphate (G6P), glutamine, adenosine, L-carnitine, and choline exhibited similar trends in both db/db mice and STZ-induced rat models of DE, suggesting their potential as reliable biomarkers. Twelve weeks of SAL treatment demonstrated a positive regulatory effect on glucose metabolism, the glutamate–glutamine cycle, and lipid metabolism. Conclusions: This study identifies key metabolic alterations in DE and demonstrates the therapeutic potential of SAL in modulating these disturbances, offering valuable insights for targeted interventions in diabetic complications.

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.

Desorption Electrospray Ionization-Mass Spectrometry Imaging-Based Spatial Metabolomics for Visualizing and Comparing Ginsenosides and Lipids among Multiple Parts and Positions of the Panax ginseng Root.

Ginsenosides and lipids are both bioactive ingredients for ginseng. Targeting these two categories of components, this study was designed to develop desorption electrospray ionization-mass spectrometry imaging approaches and spatial metabolomics strategies, achieving the visualization and differentiation among different parts of Panax ginseng root (e.g., rhizome, main root, lateral root, fibrous root, and adventitious root). Potential chemical markers were identified by searching an in-house ginsenoside library and online Lipid Maps database, together with high-resolution MS2 data analysis. Six ginsenosides and 11 lipids were diagnostic to differentiate five different parts of the P. ginseng root. Additionally, three ginsenosides and 20 lipids were identified as differential markers among the six positions of the main root of P. ginseng. High-abundance malonyl- and oleanolic acid-ginsenosides were observed in the rhizome. These results assist in understanding the accumulation of bioactive molecules all through the root of P. ginseng, which can benefit its quality control and rational use.

Enhancing Solanine Production and Antifungal Activity by Streptomyces abikoensis XH-17 through Combined Ribosome Engineering and Post-Translational Modification

Solanine, a strong poison alkaloid typically produced by staple food crops, such as sprouted potatoes, poses a potential risk to food safety, therefore, controlling solanine levels is one of the important targets for human health. Streptomyces species are ubiquitous across diverse environments and are acclaimed for their extensive production of bioactive compounds, including antibiotics, anticancer agents, and immunosuppressants. Despite their potential, many biosynthetic gene clusters (BGCs) in Streptomyces remain silent under standard laboratory conditions. The present study introduces a combination strategy that integrates ribosome engineering and post-translational modification (PTM) to activate the silent BGCs in Streptomyces XH-17, which was identified as S. abikoensis by whole gene cluster sequencing and phylogenetic analysis. The antimicrobial activity of the engineered strain increased by 3.74-fold, 1.40-fold, and 4.08-fold against Alternaria alternata, Fusarium oxysporum, and F. proliferatum, respectively. The main compounds responsible for antifungal activity were identified as α-chaconine and α-solanine by high-resolution mass spectrometry (HRMS), and their BGCs were silent in the wild type (WT). Compared to WT, the two compounds’ production increased by 5.78-fold and 4.68-fold in engineered strain XH-17rpoB+Svp, respectively, and the biosynthetic pathways of α-chaconine and α-solanine were inferred by bioinformatics analysis. This is the first to identify solanine and presumed its biosynthetic pathway from Streptomyces. Our research provides new insights into the control of solanine to protect food safety from Streptomyces contamination. The results from the current investigation provide an effective pipeline to activate silent gene clusters in Streptomyces and offer new insight into discovering new bioactive compounds within this genus.

Associations between volatile organic compounds exposure and multiple oxidative damage biomarkers: Method development, human exposure, and application for e-waste pollution prediction

Atmospheric monitoring studies reveal substantial health risks from exposure to volatile organic compounds (VOCs) for workers and nearby children in e-waste recycling areas (ERA), yet internal exposure risks are seldom examined. To address this, we developed a method to simultaneously analyze 12 urinary VOC metabolites (mVOCs) and oxidative damage biomarkers (ODBs) in workers and children from ERA and general adults from control areas using ultrahigh performance liquid chromatography coupled with quadrupole/orbitrap high-resolution mass spectrometry (UPLC-Orbitrap-HRMS). The results showed that e-waste workers exhibited significantly higher levels of VOC exposure and ODBs than e-waste children and control adults. Exceeding 91.1 %, 69.1 %, 20.8 %, 19.7 %, and 3.26 % of e-waste workers faced non-carcinogenic risk from exposure to acrolein, acrylonitrile, acrylamide, 1,3-butadiene, and 1,2-dichloroethane, respectively. The weighted quantile sum, quantile g-computation, and Bayesian kernel machine regression models consistently indicated significant positive associations between these VOC mixtures and cholesterol ODB levels (i.e., glycocholic acid, cholic acid, and glycochenodeoxycholic acid), highlighting the necessity for improved protective measures for occupational workers. Interestingly, cholesterol ODBs significantly mediated the association between VOCs exposure and nucleic acid ODBs, accounting for 12.0–26.0 % of the association with 8-hydroxy-2′-deoxyguanosine (an oxidative DNA damage biomarker) and 25.4–53.4 % with 8-hydroxyguanosine (an oxidative RNA damage biomarker). This suggests that cholesterol ODBs potentially serve as better indicators of health risks from VOC exposure than nucleic acid ODBs. Additionally, the combination of mVOCs and ODBs (Mean AUC: 0.906, ACC: 0.821) as exposure fingerprints outperformed either mVOCs (Mean AUC: 0.878, ACC: 0.802) or ODBs (Mean AUC: 0.843, ACC: 0.768) alone in predicting the presence of e-waste pollution, underscoring the importance of integrating exposure and effect biomarker fingerprints to accurately capture e-waste pollution characteristic. Our findings offer a novel approach for screening e-waste pollution in unknow e-waste recycling sites and provide a foundation for developing high-precision prediction models for other polluting industries.

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.

Associations of per- and polyfluoroalkyl substances with human milk metabolomic profiles in a rural North American cohort.

Per- and polyfluoroalkyl substances (PFAS) are a class of persistent synthetic chemicals that are found in human milk and are associated with negative health effects. Research suggests that PFAS affect both lactation and the human metabolome. We measured perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) in the milk of 425 participants from the New Hampshire Birth Cohort Study using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A nontargeted metabolomics assay was performed using LC with high-resolution MS, and metabolites were identified based on in-house database matching. We observed six metabolic profiles among our milk samples using self-organizing maps, and multinomial logistic regression was used to identify sociodemographic and perinatal predictors of these profiles, including infant sex, parity, participant body mass index, participant age, education, race, smoking status, gestational weight gain, and infant age at time of milk collection. Elevated PFOA was associated with profiles containing higher amounts of triglyceride fatty acids, glycerophospholipids and sphingolipids, and carnitine metabolites, as well as lower amounts of lactose and creatine phosphate. Lower concentrations of milk PFOS were associated with lower levels of fatty acids. Our findings suggest that elevated PFOA in human milk is related to metabolomic profiles consistent with enlarged milk fat globule membranes and altered fatty acid metabolism. Further, our study supports the theory that PFAS share mammary epithelial membrane transport mechanisms with fatty acids and associate with metabolic markers of reduced milk production.

When subcellular chemical imaging enlightens our understanding on intestinal absorption, intracellular fate and toxicity of PFOA in vitro

Perfluorooctanoic acid (PFOA) is a persistent organic pollutant that accumulates in the human body, leading to major health issues. Upon oral uptake, the gastrointestinal tract is the first biological barrier against PFOA. However, the localization of PFOA and its impact on the intestinal wall are largely unknown. Here we achieve a breakthrough in the knowledge of intestinal absorption, intracellular fate and toxicity of PFOA using in vitro assays combined with novel analytical imaging techniques. For the first time, we localized PFOA in the cytosol of Caco-2 cells after acute exposure using high spatial resolution mass spectrometry imaging, and we estimated the PFOA cytosolic concentration. Knowing that PFOA enters and accumulates in the intestinal cells, we also performed common toxicity assays assessing cell metabolic activity, membrane integrity, oxidative stress response, and cell respiration. This study integrating powerful analytical techniques with widely used toxicology assays provides insightful information to better understand potential negative impacts of PFOA and opens new opportunities in toxicology and life science in general.

Fluorotelomer Alcohol (FTOH) Emission Rates from New and Old Rain Jackets to Air Determined by Iodide High-Resolution Chemical Ionization Mass Spectrometry

Per- and polyfluoroalkyl substances (PFAS), which include fluorotelomer alcohols (FTOHs), are synthetic chemicals used in consumer products because of their water-, stain-, and grease-repellent properties; thus, PFAS are commonly found in functional clothing such as rain jackets. To date, emissions of PFAS from products to indoor air have not been well characterized, although many PFAS-containing products are used and stored indoors. We used a test chamber connected to a high-resolution time-of-flight chemical ionization mass spectrometer equipped with iodide as a reagent ion (I-HR-ToF-CIMS) to measure emission rates for four FTOHs from 10 rain jackets and one backpack cover. The materials were categorized as old/used, new, or “PFAS-free”, and they were tested under two different scenarios, i.e., immediately out of package and after airing out. We observed real-time FTOH emissions from all materials. Under the out-of-package scenario, emissions of 6:2, 8:2 and 10:2 FTOH showed characteristics that indicate mass transfer is limited by internal diffusion, with a high initial peak followed by a lower steady-state emission rate. Peak emission rates correlated well with material-phase concentrations determined by an offline extractive gas chromatography-mass spectrometry (GC-MS) method. Our results further suggest that the old, used jackets had, on average, higher peak emission rates and higher material-phase concentrations than the new jackets, largely driven by 8:2 FTOH. “PFAS-free” materials had the overall lowest emission rates and material-phase concentrations. After airing out, emission rates were on average an order of magnitude lower than peak emission rates. Our findings emphasize the importance of considering consumer products like rain jackets as sources of indoor exposure to PFAS.

Effects of relative humidity on atmospheric organosulfur species derived from photooxidation and nocturnal chemistry in a forest environment

The molecular composition of organic aerosols in ambient PM2.5 was investigated at the northern foothills of Qinling Mountain region in central China during the summer of 2022. The molecular characteristics of organic matter were analyzed using ultrahigh performance liquid chromatography coupled with high-resolution Orbitrap mass spectrometry. The number of molecular formula assignments was dominated by organosulfur species (OrgS, on average 28–47% in total). Both the number and peak area of OrgS increased significantly with higher relative humidity (RH), while those of CHO and CHON species decreased, indicating the different impacts of RH on individual organic groups. The entire study period was divided into two distinct stages, including a low RH and a high RH period (LRH and HRH). The enhanced formation of CHOS with O>7 in HRH was primarily attributed to photochemical oxidation, whereas the increase in CHONS with O>7 was driven by enhanced NO3 radical-initiated oxidation under elevated RH conditions. Nearly 50% of OrgS presented only in HRH had aliphatic structures with C≥9. Although isoprene-derived organosulfates dominated the peak area across the entire period, the monoterpenes and long-chain alkanes-derived organosulfates largely increased in HRH. The strong correlations between aerosol liquid water content and OrgS containing high oxygen content (O>7) indicate that aqueous-phase reactions played a crucial role in multigenerational oxidation of OrgS. This study highlights the important effects of RH on the formation of OrgS, particularly for organosulfates derived from monoterpenes and long-chain alkanes.

Supramolecular biosolvent extraction of antioxidants from orange peel residues from the tea industry

The growing interest in natural antioxidants across various industries has spurred the development and use of alternative green methods for valorizing plant biomass. Supramolecular solvents (bioSUPRAS), composed of self-assembled amphiphilic aggregates, have shown significant potential for the recovery of high-value compounds from plant biomass for industrial applications while adhering to numerous green chemistry principles. In this study, we evaluated various bioSUPRAS (sponge bioSUPRAS of 1,2-octanediol and cubosomic bioSUPRAS of 1,2-hexanediol) and different extraction conditions for the recovery of antioxidants from orange peel waste generated by the tea industry. Sponge bioSUPRAS were selected as optimal and the best conditions for formation consisted of a medium of 15 % v/v of 1,3-propanediol as co-solvent and 85 % v/v of water (acidified with 1 % v/v acetic acid). The most suitable extraction conditions were 1:12 mL:g bioSUPRAS-to-solid ratio at room temperature for 30 min, resulting in a maximum yield of 12.9 ± 1.4 mg GAE/g. Using liquid chromatography coupled with high-resolution tandem mass spectrometry (LC-QTOF), we screened and quantified the natural compounds of interest, identifying the flavonoid hesperidin as the dominant antioxidant at 2.6 ± 0.06 mg/g. This research presents a promising method for valorizing underutilized orange peel waste and highlights the potential of these extracts as ingredients in new value-added formulations.