Liquid Chromatography-mass Spectrometer Research Articles

Screening for chemicals with thyroid hormone-disrupting effects using zebrafish embryo

Thyroid disruption is an increasingly recognized issue in the use and development of chemicals and new drugs, especially to help toxicologist to complement the reproductive and developmental toxicology information of chemicals. Still, adequate assessment methods are scarce and often suffer a trade-off between physiological relevance and labor- and cost-intensive assays. Here, we present a tiered approach for a medium-throughput screening of chemicals to identify their thyroid disrupting potential in zebrafish embryos as a New Approach Methodology (NAM). After identifying the maximum tolerated concentrations, we exposed zebrafish larvae to sub-adverse effect levels of the reference compounds benzophenone-2, bisphenol A, phenylthiourea, potassium perchlorate, propylthiouracil, and phloroglucinol to exclude any systemic toxicity. Applying the transgenic zebrafish line that carries a gene for the red fluorescence protein (Tg(tg:mCherry)) under the thyroglobulin promoter, we could identify the thyroid disrupting effects of the chemicals by a time and cost-effective image analysis measuring the fluorescence levels in the thyroid glands. Our observations could be confirmed by altered expression patterns of genes involved in the hypothalamus-pituitary-thyroid (HPT) axis. Finally, to anchor the observed thyroid disruption, we determined some changes in the Thyroid hormone levels of triiodothyronine (T3) and Thyroxine (T4) using a newly developed liquid chromatography mass spectrometric (LCMS) method. The presented approach carries the potential to extend the toolbox for legislative authorities and chemical producers for the assessment of thyroid-specific endocrine disruption and to overcome current challenges in the evaluation of endocrine disruptors.

Multiple interface coupling on natural tourmaline enables high-efficiency removal of antibiotic: Superior property and mechanism

Reasonably designing highly active, environmentally friendly, and cost-effective catalysts for efficient elimination of pollutants from water is desirable but challenging. Herein, an efficient heterogeneous photo-Fenton catalyst tourmaline (TM)/tungsten oxide (WO3-x) (named TW10) containing tungsten/boron/iron (W/B/Fe) synergistic active centers and 90% of cheap natural tourmaline (TM) mineral rich in Fe and B elements. The TW10 catalyst can quickly activate peroxymonosulfate (PMS) to generate massive active free radicals, which may induce the rapid and efficient degradation of tetracycline (TC). The TW10/PMS/Visible light system can effectively degrade up to 98.7% of tetracycline (TC) in actual waters (i.e. seawater, Yellow River, and Yangtze River water), and the catalytic degradation rates reach 1.65, 5.569, and 2.38 times higher than those of TM, WO3-x, and commercial P25 (Degussa, Germany), respectively. In addition, the catalyst can be recycled and reused multiple times. Electron spin resonance spectroscopy (EPR), X-ray photoelectron spectroscopy (XPS), and liquid chromatograph-mass spectrometer (LC-MS) analyses confirm that the synergistic catalytic effect of W/B/Fe sites on the TW10 catalyst accelerates the electron transfer between Fe(II) and Fe(III), as well as between W(V) and W(VI), and thus promotes the rapid degradation of TC. The catalytic reaction mechanism and degradation pathway of TC were explored. This work provides a feasible route for the design and development of new eco-friendly and efficient catalyst.

Phytochemical profiling and evaluation of the antidiabetic potential of Ichnocarpus frutescens (Krishna Sariva): kinetic study, molecular modelling, and free energy approach

This research explored novel antidiabetic drugs from natural sources using the Ayurvedic Rasayana herb Ichnocarpus frutescens through invitro enzyme assay, kinetics study, and computational approaches. Invitro enzyme inhibition assay demonstrated the promising inhibitory activity of root extract against alpha-amylase (α-A) and alpha-glucosidase (α-G) enzyme with IC50 value 7.34 ± 0.22 mg/ml and 4.40 ± 0.25 mg/ml respectively. Enzyme kinetic study revealed the competitive inhibition of both proteins by Ichnocarpus frutescens extract. High-Resolution Liquid Chromatography Mass Spectrometer and Docking study revealed the better binding energy of phytoconstituents 23-Acetoxysoladulcidine, Atrovirinone, Bismurrayaquinone A, Lamprolobine, Zygadenine, and Gambiriin A3 than standard drug acarbose. Molecular modelling showed stable protein-ligands binding interaction during the 100 ns simulation. It revealed comparable Root Mean Square Deviation, Radius of Gyration, and Solvent Accessible Surface Area of these compounds with acarbose. The active site residues of both proteins remained stable and showed significantly less Root Mean Square Fluctuation. Molecular Mechanics with Generalised Bonn Surface Area analysis has illustrated the similar inhibitory activity of Zygadenine for α-A, 23-Acetoxysoladulcidine, and Gambiriin A3 for α-G protein, compared to the FDA-approved drug acarbose. Thus, the study suggested that the root of Ichnocarpus frutescens can be used as α-A and α-G inhibitors and be considered a compelling lead for the medication of type 2 diabetes. Communicated by Ramaswamy H. Sarma

The distinctive hepatoprotective activity of turmeric kombucha (Curcuma longa) induced by diethylnitrosamine in Balb/C mice

This study aims to investigate the potential hepatoprotective activity of turmeric kombucha before and after fermentation and to compare such distinctive activity in turmeric kombucha versus turmeric essence beverage (turmeric beverage without fermentation). Liquid chromatography-mass spectrometer (LC-MC) analyses revealed the presence of bioactive compounds in turmeric kombucha and turmeric essence beverages. In vivo tests appraised the levels of alanine transaminase (ALT), aspartate transaminase (AST), malondialdehyde (MDA) in Balb/C mice and the histology of their livers was determined. Upon successful fermentation process new compounds such as: tetrahydrocurcumin, ferulic acid, glucuronidated curcumin, cyclofenil, acetic acid, glucuronic acid, and d-saccharic acid-1,4-lactone were produced in turmeric kombucha, which were not found in non-turmeric kombucha. The positive effect of fermentation has boosted the hepatoprotective activity of turmeric kombucha through the release of compounds and the production of new bioactive compounds. Therefore, fermented turmeric kombucha had a greater effect on the hepatoprotective activity compared to turmeric essence beverage in Balb/C mice.

Novel MIL-88B(Fe)/ZnTi-LDH high-low junctions for adsorption and photodegradation of tetracycline: Characteristics, performance, and mechanisms

In this paper, a high-efficient MIL-88B(Fe)/ZnTi-LDH high-low junction photocatalyst was successfully prepared by a simple method for the photodegradation of tetracycline (TC). The combination of MIL-88B(Fe) and ZnTi-LDH created an internal electric field and high-low junction, facilitated the separation of carriers, and thus enhanced photocatalytic activity. The optimized MZ-30% sample showed the highest photocatalytic degradation of TC about 93.51%. The photocatalytic kinetic removal rate of MZ-30% reached 0.0941 min−1, 31.36 times of MIL-88B(Fe) (0.003 min−1) and 1.7 times of ZnTi-LDH (0.0550 min−1). Furthermore, MZ-30% possessed the highest adsorption capacity for TC (543.89 mg/L). The effects of co-existing ions, initial pH, water source, and humic acid (HA) on TC degradation were examined. The main active substances of MIL-88B(Fe)/ZnTi-LDH in photocatalytic reaction were 1O2, h+, and ·O2- confirming by reactive species elimination experiment and electron spin resonance (ESR) tests. The molecular structure and toxicity of intermediates were investigated by a high-performance liquid chromatography-mass spectrometer (HPLC-MS) and Toxicity Estimation Software Tool (T.E.S.T), and the possible degradation pathway of TC was revealed. The results highlight that MIL-88B(Fe)/ZnTi-LDH high-low junction composite is a desirable photocatalyst for removing antibiotics and other emerging contaminants in water.

Seasonal changes of chemodiversity along with microbial succession in a municipal wastewater treatment plant

The relationship between chemodiversity and microbial succession in wastewater treatment plants (WWTPs) is highly intricate and bidirectional. The specific contribution of the microbial community to changes in the composition of dissolved organic matter (DOM) within different biological treatment units remains unclear, as does the reciprocal influence of DOM composition on microbial succession. In this study, spectroscopy ((Excitation-emission matrix) EEM-PARAFAC, Ultraviolet (UV)-spectrum, Fourier transform infrared spectrometer (FT-IR)), Liquid chromatograph mass spectrometer (LC‒MS) and Fourier transform ion cyclotron resonance (FT-ICR) MS along with high-throughput sequencing technology were used to explore the relationship between chemodiversity and microbial succession in WWTPs concerning seasonal changes. The results showed that WWTPs with anaerobic/anoxic/oxic (A2O) processes can metabolize and transform most of the wastewater DOM, and the anaerobic unit has the highest removal rate for fluorescence DOM (FDOM, 14.07%-64.43%); the anaerobic unit increased aliphatic/proteins and lignin-like molecules but decreased relative intensity, while the anoxic unit removed unsaturated hydrocarbons, aromatic structures, and lignin-like substances. The impact of seasonal changes on the composition and removal of FDOM and DOM in wastewater treatment is significant, and the variations that occur during different seasons affect microbial activity, as well as the production, degradation, and transformation of organic compounds throughout the wastewater treatment process. Network analysis shows that Parcubacteria_genera_incertae_sedis plays a crucial role in DOM chemodiversity, highlighting the crucial contribution of microbial communities to both the structure and operation of the entire DOM network. The results in this study could provide some theoretical and practical basis for guiding the process optimization of WWTPs.

A LC-MS/MS procedure for the analysis of 19 perfluoroalkyl substances in food fulfilling recent EU regulations requests

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are synthetic, stable, fluorinated molecules widely used in consumer products. They are non-biodegradable, persistent and bio-accumulating. In 2020 European Food Safety Authority (EFSA) lowered the Tolerable Weekly Intake (TWI) for the four PFASs (PFOA, PFOS, PFNA, PFHxS) and in 2022, the EU issued a Recommendation asking to monitor twenty-one PFASs in food. Since 1st January 2023 limits in food were set. Here we report a sensitive, straightforward and robust procedure enabling the determination of 19 PFAS in food matrices using a liquid chromatography mass spectrometer (LC–MS/MS). Few are the published methods applicable to the different food matrices and covering the molecules listed in Recommendation 2022/1431, fulfilling the LOQs requested. The method was satisfactory validated (UNI CEI EN ISO/IEC 17025:2018 and Regulation (EU) 2022/1428) and used to investigate hen egg samples, highlighting home-produced eggs as the more critical egg farming process for PFAS accumulation.

SERS study of classical and newly β-lactams-metal complexation based on in situ laser-induced coral reefs-like silver photomicroclusters: In vitro study of antibacterial activity

The influence of metal complexation of two polar β-lactam antibiotics was investigated using surface enhanced Raman spectroscopy (SERS) technique. SERS method was applied to track the structural changes and the degradation behaviour of the studied compounds upon Zinc (II) ions-complexation. In situ laser-induced coral reefs-like photomicroclusters have been utilized as a SERS platform. The produced coral reefs-like photomicroclusters were characterized using scanning electron microscopy (SEM) and transmission electron microscope (TEM). The antibacterial efficiency of the antibiotics was investigated and compared before and after metal complexation using two techniques; agar well diffusion and growth curve. To provide a detailed elucidation of the complexation reaction, mass fragmentation of metal- antibiotics complexes was investigated using liquid chromatography/mass spectrometric (LC/MS) technique. It was found that metal complexation of classical β-lactam antibiotic (Ticarcillin) promoted the rate of its degradation, leading to a decrease of the antibacterial efficiency. On the other side, the antibacterial activity of the newly developed β-lactam (Faropenem) has been greatly enhanced via metal-complexation reaction.

Research on the reaction path of chlorobenzene oxidation by electrochemical-sodium persulfate system

Chlorobenzene (CB) is an important organic chemical material that is volatile and difficult to degrade, and has received much attention because of its strong ozone generation potential. An electrochemical-sodium peroxydisulfate (PDS) system was constructed and the oxidation reaction path of chlorobenzene in this system was analyzed. The effects of current density, PDS concentration, initial pH, CB blow-off gas ratio and temperature on the oxidation and mineralization rate of chlorobenzene in the system were investigated respectively. At a current density of 168 A/m2, a PDS concentration of 0.5 mol/L, an initial pH of 10, a CB blow-off gas ratio of 20% and a reaction temperature of 60 °C, the CB conversion and mineralization rates were able to reach more than 90%. The results of electron paramagnetic resonance (EPR) experiments using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and 2,2,6,6-tetramethyl-4-piperidone hydrochloride (TEMP) as spin trapping agents indicate the presence of ⦁OH, · SO4− and 1O2 in the system. The signal of ·O2− was also captured after the quenching of ⦁OH, which further indicates the presence of 1O2. And the results of active substance quenching experiments showed that the active species that mainly contributed to the oxidation of chlorobenzene included ⦁OH, · SO4− and 1O2, and their contributions to the oxidation of chlorobenzene were 25.0%, 31.7% and 22.2%, respectively. The Liquid Chromatograph Mass Spectrometer (LC-MS) characterization results showed that the formation of chlorophenol and hydroquinone and their ring-opening reactions were the most critical processes in the oxidative decomposition of chlorobenzene, and the reaction pathways for the oxidation of chlorobenzene by ⦁OH, · SO4− and 1O2 were proposed by these characterization results.

Metabolic features of orbital adipose tissue in patients with thyroid eye disease.

Thyroid eye disease (TED) is the most frequent orbital disease in adults and is characterized by the accumulation of orbital adipose tissue (OAT). It can lead to eyelid retraction or even vision loss. Orbital decompression surgery serves as the primary treatment for inactive TED by removing the excess OAT. However, there is a lack of alternative treatments to surgery due to the unclear understanding of the pathogenesis, particularly the metabolic features. Accordingly, our study was implemented to explore the content and features of metabolites of OATs from TED patients. The OATs used in the current study were obtained from the orbital decompression surgery of seven patients with inactive TED. We also collected control OATs from eye surgical samples of five individuals with no history of autoimmune thyroid diseases, TED, or under non-inflammatory conditions. The liquid chromatography mass spectrometer was used for the measurements of the targeted metabolites. Afterwards, we performed differential metabolite assay analysis and related pathway enrichment analysis. In our study, a total of 149 metabolite profiles were detected in all participants. There were significant differences in several metabolite profiles between the TED group and the control group, mainly including uric acid, oxidized glutathione, taurine, dGMP, oxidized glutathione 2, uracil, hexose-phosphate, 1-methylnicotinamide, D-sedoheptulose 1,7-bisphosphate, and uridine 5'-monophosphate (all p-value < 0.05). The TED-related pathways identified included purine metabolism, beta-alanine metabolism, glutathione metabolism (p-values < 0.05). Our study found overlaps and differences including uric acid and uracil, which are in accordance with metabolites found in blood of patients with TED from previous study and several newly discovered metabolite by our study such as hexose-phosphate, 1-methylnicotinamide, D-sedoheptulose 1,7-bisphosphate, compared to those tested from blood, OAT, or urine samples reported in previous studies. The findings of our study shed light on the metabolic features of OAT in individuals with TED. These results may help identify new treatment targets for TED, providing potential avenues for developing alternative treatments beyond ophthalmic surgery.

Diet, physical activity, and UV protection comprehensively influenced vitamin D status in college students: a cross-section study from China

BackgroundVitamin D deficiency is one of the most prevalent health problems worldwide in all age groups, whereas vitamin D status of Chinese college students was seldom studied in China. The purpose of this study was to explore the vitamin D status in Chinese college freshmen and its influencing factors, providing evidence for nutrition strategy application.MethodsInformation including demographic status, diet habit, physical activity, and ultraviolet ray (UV) protection was collected by online questionnaire. Serum 25(OH)D3 concentrations were measured using a liquid chromatograph mass spectrometer. Multivariate linear regression analyses were used to explore the comprehensive influence of diet, physical activity and UV protection on serum 25(OH)D3 levels.ResultsTotally 1667 freshmen from 26 provinces, autonomous districts or municipalities, were recruited, with a mean age of 18.6 ± 0.9 years. The mean serum 25(OH)D3 levels were 18.1 ± 6.3 ng/mL and the proportion of vitamin D deficiency and insufficiency was 67.5% and 27.8%, respectively. Multivariate linear regression indicated that higher intake of milk and yogurt, calcium or vitamin D supplementation, and longer time of outdoor activity were positively linked to higher serum 25(OH)D3, while higher intake of candy and higher UV protection index were negatively associated with serum 25(OH)D3, after adjusted for age, gender, region of original residence, latitudes, longitude and BMI.ConclusionsVitamin D deficiency is very common in Chinese college students. Milk and yogurt intake and outdoor activity should be encouraged while candy intake should be limited for preventing vitamin D deficiency. Public health policies should focus on these changeable lifestyles and consider well-balanced guidelines on UV protection and vitamin D supplementation.

Insights into the Molecular Motion of Benzotriazole in the Volatile Corrosion Inhibitor Packaging: A Detection and Mass Transfer Study

A new methodology using microwave extraction, gas-diffusion microextraction (GDME) and high-performance liquid chromatography-mass spectrometer (HPLC-MS) was developed for the analysis of the quantitative detection of gaseous and solid benzotriazole (BTA) and the mass transfer behavior of BTA in volatile corrosion inhibitor (VCI) packaging. The best extraction conditions of BTA in the VCI films were obtained, and the vapor pressure of BTA in the VCI packaging was detected and characterized by a mathematical model using the new methodology. The migration content of BTA in the VCI films and the BTA content on the surface of the films were detected, and the diffusion coefficients at three temperatures were calculated. The vapor pressure and diffusion coefficients of BTA increased with increasing temperature, and the volatilization of BTA promoted the migration of BTA from the VCI films. Moreover, a molecular dynamics (MD) simulation was performed to determine the migration of the BTA molecules within the VCI films at three temperatures; the overall trend of the experimental values was the same and the simulated values were generally within two orders of magnitude of the corresponding experimental values, with the difference likely due to the ignoring of the crystallinity of LDPE.

Activation of persulfate by heterogeneous nano zero-valent iron/halloysite nanotubes: reaction behavior, mechanism, and implication for tetracycline hydrochloride degradation.

A novel composite (nZVI/HNTs) was prepared via incorporating nano zero-valent iron (nZVI) on halloysite nanotubes (HNTs) for degrading tetracycline hydrochloride (TCH) with existence of persulfate (PS). The adsorption process of nZVI/HNTs to TCH conformed to the Freundlich isotherm model and pseudo-second-order kinetic model, and its maximum adsorption capacity was 76.62mg·g-1. Furthermore, the nZVI/HNTs + PS system exhibited satisfactory degradation efficiency (84.21%) for TCH, and stable nZVI/HNTs (Fe leaching < 0.001mg·L-1) could be reused. When nZVI/HNTs dosage, PS dosage and temperature increased, TCH degradation could be enhanced. After four cycling, nZVI/HNTs + PS system had still 65.8% degradation for TCH. The quenching tests and EPR analysis evidenced that SO4•- was predominant instead of •OH in such system. Three possible pathways of TCH degradation were provided through the liquid chromatograph-mass spectrometer (LC-MS) determination. Meanwhile, the biological toxicity prediction analysis indicated that the nZVI/HNTs + PS system would be an environment friendly treatment method toward TCH pollution.

Enhanced organic contaminants degradation via coupling molybdenum powder with tripolyphosphate in Fe(Ⅱ)-based peroxymonosulfate activation

To overcome the challenges of pH application range, slow cycling of Fe(III)/Fe(II) and low oxidant activation efficiency, we propose a strategy of combining molybdenum powder (Mo) cocatalyst with sodium tripolyphosphate (STPP) to accelerate peroxymonosulfate (PMS) activation and achieve efficient degradation of acetaminophen (ACT). The ACT degradation efficiency and rate were 99.7% and 0.065 min−1, respectively, which were significantly improved compared to the system without Mo due to the abundance of active sites of Mo that accelerate the dissolved Fe species complexed with STPP. Additionally, the degradation efficiency remained above 95%, and there was only a slight change in morphology after 5 cycles, demonstrating the excellent co-catalytic performance and reusability of Mo. The several oxidizing active substances (OH, SO4−, 1O2, Fe(Ⅳ)) were synergistically worked for ACT removal, which were investigated the origin and activation mechanism via multiple measures. Satisfactorily, the system exhibited desirable anti-jamming capability and superiority in the removal of various contaminants. ACT degradation intermediate products were measured and proposed three degradation pathways according to the results of liquid chromatograph-mass spectrometer (LC-MS). The development of combining Mo and STPP for organic pollutant degradation is significant in broadening the application range of PMS-AOPs in environmental remediation.

Degradation of oxytetracycline in wastewater based on activated persulfate by biosynthesized iron oxide nanoparticles and carbon nanotube-modified biochar

In this study, a green and safe modified biochar (OBC) was successfully prepared by combining biosynthesized iron oxide nanoparticles with carbon nanotubes to activate peroxydisulfate for oxytetracycline (OTC) degradation. The OBC exhibited excellent catalytic performance and 91 % OTC was removed based on optimized preparation and operating conditions (initial concentration of 50 mg L−1). Multiple quenching experiments and free radical assays revealed that singlet oxygen (1O2) was the sole active species. Besides, the pathway of 1O2 production was inferred by comprehensive characterization analysis (SEM−EDS, XRD, FTIR, XPS). The OTC removal was mainly attributed to the non-radical pathway consisting of OBC adsorption, 1O2 oxidation, and direct electron transfer combined with the electrochemical measurement results. Meanwhile, the stability of the catalytic system was determined by adjusting the solution parameters. The Liquid Chromatography Mass Spectrometer (LC-MS) showed that OTC was converted to small molecules by dehydration, amino, methyl shedding, or dehydroxylation. This clean, reliable, and energy-efficient activation method will provide insight into the effective treatment of antibiotics from wastewater.

Saikosaponins regulate bile acid excretion in mice liver and ileum by activating farnesoid X receptor and bile acid transporter.

Radix Bupleuri exerts effective hepatoprotective and cholagogic effects through its Saikosaponins (SSs) component. Therefore, we attempted to determine the mechanism of saikosaponins used to promote bile excretion by studying their effects on intrahepatic bile flow, focusing on the synthesis, transport, excretion, and metabolism of bile acids. C57BL/6N mice were continuously gavaged with saikosaponin a (SSa), saikosaponin b2 (SSb2 ), or saikosaponin D (SSd) (200 mg/kg) for 14 days. Liver and serum biochemical indices were determined using Enzyme-linked immunosorbent assay (ELISA) kits. In addition, an ultra-performance liquid chromatography-mass spectrometer (UPLC-MS) was used to measure the levels of the 16 bile acids in the liver, gallbladder, and cecal contents. Furthermore, SSs pharmacokinetics and docking between SSs and farnesoid X receptor (FXR)-related proteins were analyzed to investigate the underlying molecular mechanisms. Administration of SSs and Radix Bupleuri alcohol extract (ESS) did not cause significant changes in alanine aminotransferase (ALT), aspartate aminotransferase (AST), or alkaline phosphatase (ALP) levels. Saikosaponin-regulated changes in bile acid (BA) levels in the liver, gallbladder, and cecum were closely related to genes involved in BA synthesis, transport, and excretion in the liver. Pharmacokinetic studies indicated that SSs were characterized by rapid elimination (t1/2 as 0.68-2.47 h), absorption (Tmax as 0.47-0.78 h), and double peaks in the drug-time curves of SSa and SSb2 . A molecular docking study revealed that SSa, SSb2 , and SSd docked well with the 16 protein FXR molecules and target genes (<-5.2 kcal/mol). Collectively, saikosaponins may maintain BA homeostasis in mice by regulating FXR-related genes and transporters in the liver and intestine.

Fe3N sites anchored reduced graphene oxide activate peroxymonosulfate via singlet oxygen dominated process: Performance and mechanisms

Advanced oxidation processes (AOPs) have attracted much attention due to their adaptability to complex water environments. In this study, new catalysts (Fe/N-rGOs) with three dimensional (3D) interpenetrating structure were fabricated from the iron phthalocyanine (FePc) anchoring on reduced graphene oxide (rGO) for tetracycline (TC) degradation by activating peroxymonosulfate (PMS). Among them, the Fe/N-rGO-4 catalysts with high Fe-Nx center density exhibited the best degradation efficiency and the highest value of pseudo-first-order degradation reaction kinetic (k = 0.185 min−1), which was approximately 18.5, 4.2, and 2.9 times higher than the rates achieved by the pristine PMS, rGO/PMS, and calcining FePc nanoclusters without rGO (Fe/N NPs/PMS) systems, respectively. Besides, Fe/N-rGO-4 exhibited satisfactory catalytic activity over a wide pH range (3.0–9.5) and remarkable stability of degradation performance after four consecutive cycles. Quenching experiments and electrochemical analysis demonstrated that 1O2 was the primary reactive species, which was facilitated by the mediated electron transfer originating from the C-N group with graphitic N at the defective edges of rGO. The π-conjugated region resulting from π-π stacking interaction between rGO and FePc is the pathway of electron transfer. Furthermore, Fe3N sites were proved as the primary catalytic active sites, which dominated the catalytic performance. Three degradation pathways of TC including twelve intermediates were proposed based on the Liquid Chromatograph Mass Spectrometer (LC-MS) analysis. Generally, this work highlighted the great potential of Fe/N-rGOs catalysts and provided a new insight into the synthesis of high-performance carbon-based catalysts for environmental remediation.

Antimicrobial mechanisms and secondary metabolite profiles of Streptomyces hygroscopicus subsp. hygroscopicus 5-4 against banana fusarium wilt disease using metabolomics.

Fusarium wilt of bananas (FWB) is seriously affecting the sustainable development of the banana industry and is caused by the devastating soil-borne fungus Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4). Biological control is a promising strategy for controlling Fusarium wilt in bananas. We previously identified Streptomyces hygroscopicus subsp. hygroscopicus 5-4 with strong antifungal activity against the FWB. The most possible antimicrobial mechanism of strain 5-4 was explored using the metabolomics approach, light microscopy imaging, and transmission electron microscopy (TEM). The membrane integrity and ultrastructure of Foc TR4 was damaged after extract treatment, which was supported by the degradation of mycelium, soluble protein content, extracellular reducing sugar content, NADH oxidase activity, malondialdehyde content, mitochondrial membrane potential, and mitochondrial respiratory chain complex enzyme activity. The extracts of strain 5-4 cultivated at different times were characterized by a liquid chromatography-mass spectrometer (LC-MS). 647 known metabolites were detected in the extracts of strains 5-4. Hygromycin B, gluten exorphin B4, torvoside G, (z)-8-tetradecenal, piperitoside, sarmentosin, pubescenol, and other compounds were the main differential metabolites on fermentation culture for 7 days. Compared with strain 5-4 extracts, hygromycin B inhibited the mycelial growth of Foc TR4, and the EC50 concentration was 7.4 μg/mL. These results showed that strain 5-4 could destroy the cell membrane of Foc TR4 to inhibit the mycelial growth, and hygromycin B may be the key antimicrobial active metabolite. Streptomyces hygroscopicus subsp. hygroscopicus 5-4 might be a promising candidate strain to control the FWB and provide a scientific basis for the practical application of hygromycin B as a biological control agent.

Enhancement of catalytic activity for hydrogenation of nitroaromatic by anionic metal-organic framework

Nitroaromatic hydrogenation catalysis without precious metals remains a longstanding challenge. The rate of electron transfer is the crucial factor affecting hydrogenation catalysis. Herein, an ionic Cd-based metal-organic framework (I-Cd-MOF) exhibiting a unique structure with one-dimensional (1D) opening nanochannels and good electron transfer ability was synthesized for catalyzing hydrogenation of 4-nitrophenol (4-NP). The catalytic activity of the unique I-Cd-MOF without noble metals is detected, which is higher than most reported noble metal catalysts. Remarkably, the reaction rate of I-Cd-MOF (4.28 min−1) is about 47.6 times higher than that of the Cd-based neutral MOF (N-Cd-MOF) with the similar crystalline structure. Liquid chromatograph mass spectrometer (LC-MS) and theoretical results demonstrate that 4-NP and five intermediates are stabilized in the channels of I-Cd-MOF, which increases the possibility of contact with H* and H2 generated at the Cd sites. The I-Cd-MOF was extended to other nitroaromatic hydrogenation catalysis, which still displays excellent activity. More importantly, the I-MOF@Filter membrane was successfully constructed for continuous hydrogenation catalytic reactions, which maintains a high catalytic performance after 7 cycles of recycling without washing. This work fills in the application of the I-MOFs in hydrogenation catalytic reactions and provides an effective way for the rapid and green degradation of nitroaromatic compounds.

Serum lipidomics reveals phosphatidylethanolamine and phosphatidylcholine disorders in patients with myocardial infarction and post-myocardial infarction-heart failure

BackgroundMyocardial infarction (MI) and post-MI-heart failure (pMIHF) are a major cause of death worldwide, however, the underlying mechanisms of pMIHF from MI are not well understood. This study sought to characterize early lipid biomarkers for the development of pMIHF disease.MethodsSerum samples from 18 MI and 24 pMIHF patients were collected from the Affiliated Hospital of Zunyi Medical University and analyzed using lipidomics with Ultra High Performance Liquid Chromatography and Q-Exactive High Resolution Mass Spectrometer. The serum samples were tested by the official partial least squares discriminant analysis (OPLS-DA) to find the differential expression of metabolites between the two groups. Furthermore, the metabolic biomarkers of pMIHF were screened using the subject operating characteristic (ROC) curve and correlation analysis.ResultsThe average age of the 18 MI and 24 pMIHF participants was 57.83 ± 9.28 and 64.38 ± 10.89 years, respectively. The B-type natriuretic peptide (BNP) level was 328.5 ± 299.842 and 3535.96 ± 3025 pg/mL, total cholesterol(TC) was 5.59 ± 1.51 and 4.69 ± 1.13 mmol/L, and blood urea nitrogen (BUN) was 5.24 ± 2.15 and 7.20 ± 3.49 mmol/L, respectively. In addition, 88 lipids, including 76 (86.36%) down-regulated lipids, were identified between the patients with MI and pMIHF. ROC analysis showed that phosphatidylethanolamine (PE) (12:1e_22:0) (area under the curve [AUC] = 0.9306) and phosphatidylcholine (PC) (22:4_14:1) (AUC = 0.8380) could be potential biomarkers for the development of pMIHF. Correlation analysis showed that PE (12:1e_22:0) was inversely correlated with BNP and BUN, but positively correlated with TC. In contrast, PC (22:4_14:1) was positively associated with both BNP and BUN, and was negatively associated with TC.ConclusionsSeveral lipid biomarkers were identified that could potentially be used to predict and diagnose patients with pMIHF. PE (12:1e_22:0) and PC (22:4_14:1) could sufficiently differentiate between patients with MI and pMIHF.