Electrospray Ionization Mass Spectra Research Articles

4-Diphenylaminobenzaldehyde-formulated isonicotinohydrazide for the rapid recognition of Cu2+ ions; Application of RGB tool, pharmaceutical samples, and DFT studies

High copper concentrations have been linked to several harmful illnesses in humans and negatively affect the kidneys and liver. The design and synthesis of simple and effective chemosensors for recognizing copper (Cu2+) ions are extremely significant. However, most of the colorimetric chemosensors have been developed using an intramolecular charge transfer binding mechanism based on donor-acceptor conjugation systems. This study aimed to fabricate a novel Schiff base colorimetric chemosensor, N'-(4-(diphenylamine) benzylidene) isonicotinohydrazide (DPBA-INH), with high sensitivity and selectivity towards copper ions in the semi-aqueous medium (DMSO: H2O, 7:3, v/v). The synthesized receptor DPBA-INH was distinguished using various spectroscopic methods, including NMR analysis, Fourier transform infrared spectroscopy, HRMS, and ultraviolet-visible (UV–vis) spectroscopy. When exposed to sunlight, the receptor DPBA-INH with Cu2+ ion complexation exhibited a color change from orange to pale yellow. A Job's plot and electrospray ionization mass spectra confirmed the presence of complexation at a stoichiometric binding proportion of the receptor to Cu2+ ions of 1:1. The receptor DPBA-INH interacts with Cu2+ ions in a 1:1 stoichiometric manner with a detection limit of 1.40 × 10−7 M. The experimental results were supported by a theoretical DFT study. Moreover, the receptor effectively measured Cu2+ ions in pharmaceutical samples and test strip analyses. Furthermore, the rapid colorimetric recognition of Cu2+ ions in a semi-aqueous medium was achieved using DPBA-INH, which was demonstrated to be an excellent receptor. Notably, DPBA-INH was employed to detect copper ions in real water samples.

Design of High-Performance Molecular Imprinted Magnetic Nanoparticles-Loaded Hydrogels for Adsorption and Photodegradation of Antibiotics from Wastewater.

A hydrogel formulation of 2-hydroxy ethyl methacrylate (HEMA) containing covalently linked magnetite nanoparticles was developed to actively facilitate the selective removal and photocatalytic degradation of antibiotics. To this purpose, the hybrid materials were molecularly imprinted with Lomefloxacin (Lome) or Ciprofloxacin (Cipro), achieving a selectivity of 60% and 45%, respectively, starting from a solution of XX concentration. After the adsorption, the embedded magnetite was used with the double function of (i) magnetically removing the material from water and (ii) triggering photo-Fenton (PF) reactions assisted by UVA light and H2O2 to oxidize the captured antibiotic. The success of the material design was confirmed by a comprehensive characterization of the system from chemical-physical and morphological perspectives. Adsorption and degradation tests demonstrated the material's ability to efficiently degrade Lome until its complete disappearance from the electrospray ionization (ESI) mass spectra. Regeneration tests showed the possibility of reusing the material for up to three cycles. Ecotoxicological tests using algae Rapidocelis subcapitata, crustaceans Daphnia magna, and bacteria Vibrio fischeri were performed to evaluate the ecosafety of our synthesized materials.

Zwitterionic Thiolate-Protected Ag22(0/I) and Ag20(I) Clusters: Assembly, Structural Characterization, and Antibacterial Activity.

Zwitterionic thiolate ligands have the potential to introduce novel assembly modes and functions for noble metal clusters. However, their utilization in the synthesis of silver clusters remains understudied, particularly for the clusters containing reductive Ag(0) species. In this article, we report the first synthesis of a mixed-valence silver(0/I) cluster protected by zwitterionic Tab as thiolate ligands (Tab = 4-(trimethylammonio)benzenethiolate), denoted as [Ag22(Tab)24](PF6)20·16CH3OH·6Et2O (Ag22·16CH3OH·6Et2O), alongside an Ag(I) cluster [Ag20(Tab)12(PhCOO)10(MeCN)2(H2O)](PF6)10·11MeCN (Ag20·11MeCN). Ag22 has a distinct hierarchical supratetrahedral structure with a central {Ag6} kernel surrounded by four [Ag4(Tab)6]4+ units. High-resolution electrospray ionization mass spectra demonstrate that Ag22 has two free electrons, indicating a superatomic core. Ag20 has a drum-like [Ag12(Tab)6(PhCOO)6(H2O)]6+ inner core capped by two tetrahedral-like [Ag4(Tab)3(PhCOO)2(MeCN)]2+ units. Ag20 can be transformed into Ag22 after its reaction with NaBH4 in solution. Antibacterial measurements reveal that Ag22 has a significantly lower minimum inhibitory concentration than that of the Ag20 cluster. This work not only extends the stabilization of silver(0/I) clusters to neutral thiol ligands but also offers new materials for the development of novel antibacterial materials.

Synergistic exploration of antimicrobial potency, cytotoxicity, and molecular mechanisms: A tripartite investigation integrating in vitro, in vivo, and in silico approaches for pyrimidine‐based metal (II) complexes

We synthesized and characterized bioactive metal (II) complexes from a pyrimidine‐based Schiff base ligand, 4‐[2‐(4‐chlorobenzylidene) hydrazinyl]‐7H‐pyrrolo[2,3‐d]pyrimidine. Through thorough elemental analysis and various physicochemical techniques, we characterized both the ligand and its Zn(II), Cd(II), and Hg(II) complexes. Coordination of the metallic ion was established via nitrogen atoms from the ligand's pyrrolo and pyrimidine rings, yielding tetrahedral complexes of the type [M(PPHpCB)2]. These complexes are identified as non‐electrolytes due to their low molar conductance. Furthermore, we investigated the coordination behavior of the pyrimidine‐based Schiff base ligand (HPPHpCB) with metal ions through comprehensive spectroscopic analysis. 1H NMR spectral data showed bonding between HPPHpCB and metal ions, while UV spectra confirmed intra‐ligand and ligand‐to‐metal charge transfer transitions, indicating coordination through nitrogen atoms. The determination of tetrahedral geometry for metal complexes confirmed their diamagnetic properties. Analysis using 13C NMR and electrospray ionization mass spectra (ESI‐MS) revealed variations in chemical shifts, confirming successful complex formation and elucidating structural modifications, electronic interactions, and metal–ligand coordination modes. Moreover, evaluation of in vitro antimicrobial activities using the minimum inhibitory concentration (MIC) approach revealed significant antibacterial and antifungal activities for Hg(II) and Cd(II) complexes, respectively. The Hg(II) complex displayed superior antioxidant activity, while Zn(II) and Cd(II) complexes also demonstrated considerable potential. In vivo, cytotoxicity assessments against Artemia salina provided insights into the cytotoxic properties of ligands and metal complexes. Computational techniques suggested their potential in combating infectious ailments. Overall, our study establishes the synthesis, characterization, and multifaceted biological activities of metal (II) complexes derived from the pyrimidine‐based Schiff base ligand, highlighting their promising role in combating various infectious diseases.

Dispersity determination of poly(ethylene glycol)s using supercritical fluid chromatography-mass spectrometry and different mass analysers.

Dispersity values are considered critical quality attributes for the quality control of poly(ethylene glycol) formulations due to the direct impact on drug performance. However, when these polymers are analysed using mass spectrometry, the design of the mass analyser can impact the oligomer response and affect the obtained dispersity values, so further understanding is needed. The deconvoluted electrospray ionisation mass spectra of poly(ethylene glycol)s obtained using supercritical fluid chromatography (SFC) hyphenated to different mass analysers were compared, and visualisation diagrams were used to understand the differences in the dispersity value calculations. Five calibration approaches based on a surrogate single oligomer that represents the whole distribution, or the whole distribution itself, for response selection, were used to evaluate ionisation efficiency prior to quantitation. The impact of using an internal standard (ISTD) on the expanded uncertainty was also assessed. Although there were challenges related to the resolution of multiply charged species when low-resolution instruments were used, similar quantitation capabilities were obtained to those when high-resolution mass analysers were used. Evaluation of approaches using a surrogate oligomer or the whole distribution suggested the independence of both approaches and a constant ionisation efficiency across the oligomer chain length. The higher degree of chromatographic resolution of SFC allowed incorporating a monodispersed ISTD to improve the accuracy and precision of the method. The use of low resolution mass analysers was sufficient to provide accurate and precise dispersity values; however, higher resolution instruments were recommended for characterisation due to the improved mass resolution of ions. The introduction of a monodispersed ISTD improved precision without compromising the calculated dispersity value due to the lack of analyte suppression.

Effect of Counterions on the Soft Ionization Mass Spectra of Analytes with Multiple Permanent Charges.

Multiply permanently charged analytes (MPCAs) are of great interest for various applications. MPCA soft ionization mass spectra (MS) strongly depend on the counterions of MPCA. We have studied thoroughly this effect to expand the use of MS in MPCA characterization. To this end, β-cyclodextrin-based MPCAs with 7 (MIM7NBCD) and 14 (MIM14BCD) quaternary ammonium charges with a series of monovalent counterions were prepared and their MS were measured using two of the most popular soft ionization techniques, electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI). MALDI MS of both analytes were well resolved, with signals assignable to the analytes only with the two least basic tested counterions (ClO4- and TfO-). Similarly, analyte-assignable signals were observed in ESI MS of MIM14BCD only with ClO4- and TfO-. The situation was opposite with ESI MS of MIM7NBCD where assignable signals were observed with Cl- but not with TfO-. Thus, to get high-quality MS, binding between the MPCA permanent charges and the counterions must be of the optimal effective strength, given also by the number of analyte permanent charges as shown by the simple combinatorial model of binding. Of practical interest is the observation that unsuitable counterions can be replaced in situ by an excess of corresponding acid. The findings form a coherent framework for interpreting and improving MPCA mass spectra.

Molybdate-Templated Luminescent Silver Alkynyl Nanoclusters: Total Structure Determination and Optical Property Analysis.

Two novel MoO42--templated luminescent silver alkynyl nanoclusters with 20-nuclearity ([(MoO42-)@Ag20(C≡CtBu)8(Ph2PO2)7(tfa)2]·(tfa-) (1)) and 18-nuclearity ([(MoO42-)@Ag18(C≡CtBu)8(Ph2PO2)7]·(OH) (2)) (tfa = trifluoroacetate) were synthesized with the green light maximum emissions at 507 and 516 nm, respectively. The nanoclusters were investigated and characterized by single-crystal X-ray crystallography, electrospray ionization mass spectrum (ESI-MS), X-ray photoelectron spectroscopy, thermogravimetry (TG), photoluminescence (PL), ultraviolet-visible (UV-vis) spectroscopy, and density functional theory calculations (DFT). The two nanoclusters differ in their structure by a supplementary [Ag2(tfa)2] organometallic surface motif, which significantly participates in the frontier molecular orbitals of 1, resulting in similar bonding patterns but different optical properties between the two clusters. Indeed, both nanoclusters show strong temperature-dependent photoluminescence properties, which make them potential candidates in the fields of optical devices for further applications.

Synthesis of substituted terpyridine nickel nitrate complexes and their inhibitory selectivity against cancer cell lines

Six terpyridine‑nickel complexes 1–6 were formed by the coordination of 4′-(4-R-phenyl)-2,2′:6′,2″-terpyridine (R = hydroxyl (L1), methoxyl (L2), methylsulfonyl (L3), fluoro (L4), bromo (L5), iodo (L6)) derivatives to nickel nitrate. The compositions and structures of these complexes were analyzed by Fourier Transform infrared spectroscopy (FT-IR), elemental analyses, electrospray ionization mass spectra (ESI-MS), solid-state ultraviolet-visible (UV–Vis) spectroscopy, and single crystal X-ray diffraction (1, 2 and 4) studies. In vitro anticancer cell proliferation experiments against SiHa (human cervical squamous cancer cell line) cells, Bel-7402 (human hepatoma cancer cell line), Eca-109 (human esophageal cancer cell line) and HL-7702 (human normal hepatocyte cell line) indicate that they have more excellent anti-proliferation effects than the cis-platin against Siha cells, Bel-7402 cells and Eca-109 cells. Especially, complex 5 showed a rather outstanding inhibitory effect against the SiHa cell line and was less toxic than the other compounds to the HL-7702 cell line, implying an obvious specific inhibitory effect. Therefore, complex 5 has the potential value to be developed as an anticancer cell-specific drug against human cervical squamous carcinoma. Molecular docking simulation, UV–vis absorption spectroscopy and circular dichroism experiments show that they prefer to bind to DNA part in an embedded binding manner.

Solvent-Mediated Hetero/Homo-Phase Crystallization of Copper Nanoclusters and Superatomic Kernel-Related NIR Phosphorescence.

Atomically precise superatomic copper nanoclusters (Cu NCs) have been the subject of immense interest for their intriguing structures and diverse properties; nonetheless, the variable oxidation state of copper ions and complex solvation effects in wet synthesis systems pose significant challenges for comprehending their synthesis and crystallization mechanism. Herein, we present a solvent-mediated approach for the synthesis of two Cu NCs, namely, superatomic Cu26 and pure-Cu(I) Cu16. They initially formed as a hetero-phase and then separated as a homo-phase via modulating binary solvent composition. In situ UV/vis absorption and electrospray ionization mass spectra revealed that the solvent-mediated assembly was determined to be the underlying mechanism of hetero/homo-phase crystallization. Cu26 is a 2-electron superatom with a kernel-shell structure that includes a [Cu20Se12]4- shell and [Cu6]4+ kernel, containing two 1S jellium electrons. Conversely, Cu16 is a pure-Cu(I) Cu/Se nanocluster that features a [Cu16Se6]4+ core protected by extra dimercaptomaleonitrile ligands. Remarkably, Cu26 exhibits unique near-infrared phosphorescence (NIR PH) at 933 nm due to the presence of a superatomic kernel-related charge transfer state (3MM(Cu)CT). Overall, this work not only showcases the hetero/homo-phase crystallization of Cu NCs driven by a solvent-mediated assembly mechanism but also enables the rare occurrence of NIR PH within the 2-electron copper superatom family.

Combating Alcohol Adduct Impurity in Immunosuppressant Drug Product Manufacturing: A Scientific Investigation for Enhanced Process Control.

This research aims to elucidate critical impurities in process validation batches of tacrolimus injection formulations, focusing on identification and characterization of previously unreported impurity at RRT 0.42, identified as the tacrolimus alcohol adduct. The potential root causes for the formation of new impurity was determined using structured risk assessment by cause and effect fishbone diagram. The primary objective was to propose mitigation plan and demonstrate the control of impurities with 6 month accelerated stability results in development batches. The investigation utilizes method validation and characterization studies to affirm the accuracy of quantifying the tacrolimus alcohol adduct. The research methodology employed different characterization techniques like rotational rheometer, ICP‒MS, MALDI-MS, 1H NMR, 13C NMR, and DEPT-135 NMR for structural elucidation. Additionally, the exact mass of the impurity is validated using electrospray ionization mass spectra. Results indicate successful identification and characterization of the tacrolimus alcohol adduct. The study further explores the transformation of Tacrolimus monohydrate under various conditions, unveiling the formation of Tacrolimus hydroxy acid and proposing the existence of a novel degradation product, the Tacrolimus alcohol adduct. Six-month data from development lots utilizing Manufacturing Process II demonstrate significantly lower levels of alcohol adducts. Manufacturing Process II, selectively locates Tacrolimus within the micellar core of HCO-60, this prevent direct contact of ethanol with Tacrolimus which minimizes impurity alcohol adduct formation. This research contributes to the understanding of tacrolimus formulations, offering ways to safeguard product integrity and stability during manufacturing and storage.

Identification and characterization of impurities in an insecticide, commercial chlorantraniliprole using liquid chromatography-tandem mass spectrometry.

Ensuring the global safety and effectiveness of agrochemicals has become imperative. An in-depth understanding of impurity profiles of products is crucial, especially for high-demand agrochemicals, where impurities may be more toxic and persistent than original agrochemicals. This study focuses on the detection and identification of impurities in a commercial chlorantraniliprole (CAP), an anthranilic diamide class broad-spectrum insecticide. Commercial CAP was collected from an agrochemical supplier in India and was analyzed using a high-performance liquid chromatography-photodiode array (HPLC-PDA) (Agilent 1260; wavelength, 220 nm) with a Zorbax RP SB-C18 (250 × 4.6mm, 5μm) column and liquid chromatography-mass spectrometry (LC-MS) (Agilent 6545 quadrupole time of flight (Q-TOF)) techniques to identify the impurities. The impurities were isolated by preparative HPLC using a Zorbax-DB C18 (250 × 9.4mm, 5μm) column. liquid chromatography- tandem mass spectrometry (LC-MS/MS) experiments (Q-TOF) were performed on CAP and its impurities to obtain their structural data. HPLC-PDA analysis of CAP showed four major impurities (IM-1 to IM-4) ranging from 0.76% to 4.1%. The positive ion electrospray ionization (ESI) mass spectra of CAP and its impurities showed dominant [M + H]+ ions in addition to [M + Na]+ , [M + K]+ , and [2M + Na]+ ions. High-resolution mass spectrometry (HRMS) data provided the elemental composition of the compounds, and isotopic distribution patterns revealed the number of Cl and/or Br atoms present in them. The structures of impurities were proposed based on the LC-MS/MS) data and further confirmed by nuclear magnetic resonance (NMR) data on isolated impurities/synthesis. The quality and impurities of CAP, a popular insecticide, must be assessed and described for its efficacy and safety. In this study, four impurities of CAP were detected using HPLC and successfully characterized using LC-HRMS, LC-MS/MS, and NMR data. The method is useful for verifying the purity of CAP as well as helping in the identification of its possible impurities.

Nanoscale calcium uranyl carbonate clusters in water

Aqueous calcium uranyl carbonate complexes are the predominant form of U(VI) in neutral to alkaline water in the environment, including seawater. We report a robust and repeatable synthesis of a nanoscale [(UO2)24O4(OH)12(CO3)36]44− cage cluster that we co-crystallized with Ca and Na countercations and determine its structure using single-crystal X-ray diffraction. Crystals were harvested and dissolved in water, followed by collection of electrospray ionization-mass spectra (ESI-MS). Introduction of a pH 8.1 solution containing 1.19 ± 0.04 mmol·L−1 U into the spectrometer produced broad m/z peak envelopes with −7 and 6 charge states at 1375, 1430, 1530, 1600, and 1675 m/z corresponding to mass 9625, 10,010, 10,710, 9600 and 10,080 amu, respectively. The spectra are consistent with [(UO2)24O4(OH)12(CO3)36]44− in solution (8909.07 amu), together with charge-balancing cations and H2O. Intentional fragmentation of the clusters yielded uranyl hydroxide and uranyl carbonate species containing Na. The [(UO2)24O4(OH)12(CO3)36]44− cluster is similar to that found in the mineral ewingite, which has been found to form in mine waters of an abandoned uranium mine. Demonstration of persistence of a nanoscale Ca uranyl carbonate cage cluster in aqueous solution reveals the need to re-examine aspects of environmental metal speciation to evaluate the extent to which nanoscale clusters may be important. SynopsisThis study demonstrates the existence of a nanoscale aqueous uranyl carbonate macroion at environmentally relevant pH conditions using mass spectrometry.

Trichodermic acids from an endophytic Trichoderma sp. and their antifungal activity against the phytopathogen Botrytis cinerea

Phytopathogen Botrytis cinerea is a necrotrophic pathogen with a wide host range, which causes considerable economic losses in agriculture. Consequently, it is necessary to find safe and effective antifungal agents against B. cinerea from natural sources. In this study, eight octahydronaphthalene derivatives (1−8) including four new natural products named trichodermic acids E − H (1−4), were isolated from an endophytic fungus Trichoderma sp. Their structures were determined by analysis of their nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectra (HR-ESI-MS) and by electronic circular dichroism (ECD) data. All compounds showed some extent of antifungal activities against B. cinerea with minimum inhibitory concentration (MIC) values ranging from 4 to 64 μg/mL. Notably, compound 8 showed significant inhibition with an MIC of 4 μg/mL, which was visually confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These findings provide a potential application of trichodermic acids as natural “hit” fungicides in agriculture.

Mass spectrometry study of ascorbyl palmitate as an agent for nanosomes formation

Background. Study of properties and intermolecular interactions of biologically active compounds which can be used for the purposes of transmembrane drugs delivery is a topical task of modern molecular biophysics. Ascorbyl Palmitate (AP) as a fat-soluble form of vitamin C has recently attracted attention as a promising agent for formation of nanosomes for the “fat insoluble” drug molecules transfer through membranes. However, AP is not sufficiently characterized by up-to-date soft ionization mass spectrometric techniques. Objectives. The aim of the present work is to characterize AP and its intermolecular interactions by a number of mass spectrometric techniques: Electrospray Ionization (ESI), Laser Desorption/Ionization (LDI) and Matrix-Assisted Laser Desorption/Ionization (MALDI). The comparison of these techniques applicability to the study of AP intermolecular interactions as a drug delivery assisting agent is scheduled. Methods. ESI mass spectra are obtained with triple quadrupole Micromass Quattro mass spectrometer. LDI and MALDI experiments are performed by Autoflex II mass spectrometer. Results. In the ESI experiments in the positive ion mode abundant peaks of protonated and cationized AP molecules as well as the peaks of AP clusters nAP•H+ and nAP•Na+ (n=2÷4) are revealed in the mass spectra. This result testifies to the formation of stable noncovalent complexes of the AP molecules in the polar media and confirms the AP ability of formation nanosomes for drug delivery. Analysis of LDI and MALDI mass spectra of AP in positive and negative ion modes shows that in the presence of molecular ions of AP, the peaks of AP dimers or larger AP clusters are not recorded. The ESI probing of the model system containing AP and dipalmitoylphosphatidylcholine (DPPC) reveals stable AP•DPPC•H+ complex which models the AP intermolecular interactions with the phospholipid components of biomembranes and/or liposomes under AP functioning as a drug delivery assisting agent. Conclusions. The current study demonstrates the applicability of all tested mass spectrometric techniques for AP identification in solutions and solid phase, while for the purpose of examining of the AP noncovalent complexes formation and study of AP interactions with biomolecules the ESI is defined as the most effective technique.

Meldrum-Based-1H-1,2,3-Triazoles as Antidiabetic Agents: Synthesis, In Vitro α-Glucosidase Inhibition Activity, Molecular Docking Studies, and In Silico Approach.

A series of novel alkyl derivatives (2-5a,b) and 1H-1,2,3-triazole analogues (7a-k) of Meldrum's acid were synthesized in a highly effective way by using "click" chemistry and screened for in vitro α-glucosidase inhibitory activity to examine their antidiabetic potential. 1H NMR, 13C-NMR, and high-resolution electrospray ionization mass spectra (HR-ESI-MS) were used to analyze each of the newly synthesized compounds. Interestingly, these compounds demonstrated high to moderate α-glucosidase inhibitory potency having an IC50 range of 4.63-80.21 μM. Among these derivatives, compound 7i showed extraordinary inhibitory activity and was discovered to be several times more potent than the parent compound Meldrum (1) and the standard drug acarbose. Later, molecular docking was performed to understand the binding mode and the binding strength of all the compounds with the target enzyme, which revealed that all compounds are well fitted in the active site of α-glucosidase. To further ascertain the structure of compounds, suitable X-ray single crystals of compounds 5a, 7a, and 7h were developed and studied. The current investigation has shown that combining 1H-1,2,3-triazole with the Meldrum moiety is beneficial. Furthermore, this is the first time that the aforementioned activity of these compounds has been reported.

Isolation and Quantification of 2-O-Caffeoyl-hydroxycitric Acid, an Active Component in Hot Water Extracts of Coriander (Coriandrum sativum L.), Which Inhibits Degranulation of RBL-2H3 Cells

Objectives: Natural compounds that can effectively prevent and alleviate allergic symptoms, such as hay fever, are widely sought after from sources such as natural ingredients that can be ingested daily. Coriander extracts have been reported to show anti-allergic activity; however, hot water extracts have not been tested previously. Here, we found that a hot water extract of the aerial parts of coriander inhibited the degranulation of rat basophilic leukemia cell line RBL-2H3 cells and identified the active compounds. Methods: Chromatographic methods were used to isolate compounds from the hot water extract of coriander. The chemical structures were elucidated by analyses of high-resolution electrospray ionization mass spectrum and nuclear magnetic resonance spectral data. The degranulation activity of compounds was evaluated using the β-hexosaminidase release assay. Results: We analyzed the components to identify active compounds. 2 S,3 S-2- O-caffeoyl-hydroxycitric acid (1), and 2- O-caffeoyl-hydroxycitric acid 6′- O-methyl ester (2) were isolated from the hot water extract of coriander, and both compounds showed degranulation inhibitory activity in RBL-2H3 cells at a concentration below 2.5 mM. The content of compound 1 in the freeze-dried coriander powder was calculated to be 2.0% via HPLC quantification. Conclusions: Compound 1 was considered to be the primary active contributor in the hot water extract of coriander.

Characterization of Chemical Components and Optical Properties of Toluene Secondary Organic Aerosol in Presence of Ferric Chloride Fine Particles

Iron ion is the common transition metal ion in atmospheric aerosol, which can affect the components and optics of secondary organic aerosol (SOA). In the current study, the atmospheric photooxidation of toluene to produce SOA in the presence of ferric chloride fine particles is simulated in a smog chamber; on-line and off-line mass spectrometry and spectroscopic instruments are used to characterize constituents and optics of SOA. Compare with SOA formed in the absence of fine particles, the laser desorption/ionization mass spectra of toluene SOA generated in the presence of ferric chloride fine particles show ion peaks of m/z = 163 and 178, the UV-Vis spectra of the extracting solution for toluene SOA have peaks near 400 and 700 nm, and the electrospray ionization mass spectra contain peaks at m/z = 248 and 300. Based on this spectral information, it is shown that gaseous methylcatechol formed from photooxidation of toluene may react with iron ion on the surface of fine particles by complexing and oxidation–reduction, resulting in methylbenzoquinone products and metallo-organic complex ions such as [Fe(III)(CH3C6H3OO)]+, [Fe(III)(CH3C6H3 OO)2]− and [Fe(III)(CH3C6H3OO)Cl2]−. These products have strong light absorption ability, resulting in an increase in the averaged mass absorption coefficient (<MAC>) in the 200~1000 nm range and the MAC at 365 nm (MAC365) for toluene SOA, while <MAC> and MAC365 progressively increase with an increasing concentration of ferric chloride fine particles. These results serve as experimental references for the study of the formation mechanism and optical properties of metallo-organic complexes in atmospheric aerosol particles in regions experiencing high levels of fine particles of metal and automobile exhaust pollution.

Scutellarein alleviates chronic obstructive pulmonary disease through inhibition of ferroptosis by chelating iron and interacting with arachidonate 15-lipoxygenase.

Ferroptosis, an iron-dependent cell death characterized by lethal lipid peroxidation, is involved in chronic obstructive pulmonary disease (COPD) pathogenesis. Therefore, ferroptosis inhibition represents an attractive strategy for COPD therapy. Herein, we identified natural flavonoid scutellarein as a potent ferroptosis inhibitor for the first time, and characterized its underlying mechanisms for inhibition of ferroptosis and COPD. In vitro, the anti-ferroptotic activity of scutellarein was investigated through CCK8, real-time quantitative polymerase chain reaction (RT-qPCR), Western blotting, flow cytometry, and transmission electron microscope (TEM). In vivo, COPD was induced by lipopolysaccharide (LPS)/cigarette smoke (CS) and assessed by changes in histopathological, inflammatory, and ferroptotic markers. The mechanisms were investigated by RNA-sequencing (RNA-seq), electrospray ionization mass spectra (ESI-MS), local surface plasmon resonance (LSPR), drug affinity responsive target stability (DARTS), cellular thermal shift assay (CETSA), and molecular dynamics. Our results showed that scutellarein significantly inhibited Ras-selective lethal small molecule (RSL)-3-induced ferroptosis and mitochondria injury in BEAS-2B cells, and ameliorated LPS/CS-induced COPD in mice. Furthermore, scutellarein also repressed RSL-3- or LPS/CS-induced lipid peroxidation, GPX4 down-regulation, and overactivation of Nrf2/HO-1 and JNK/p38 pathways. Mechanistically, scutellarein inhibited RSL-3- or LPS/CS-induced Fe2+ elevation through directly chelating Fe2+ . Moreover, scutellarein bound to the lipid peroxidizing enzyme arachidonate 15-lipoxygenase (ALOX15), which resulted in an unstable state of the catalysis-related Fe2+ chelating cluster. Additionally, ALOX15 overexpression partially abolished scutellarein-mediated anti-ferroptotic activity. Our findings revealed that scutellarein alleviated COPD by inhibiting ferroptosis via directly chelating Fe2+ and interacting with ALOX15, and also highlighted scutellarein as a candidate for the treatment of COPD and other ferroptosis-related diseases.

English

Common bean (Phaseolus vulgaris L.) is a major food crop in Africa and its production is plagued by diseases that reduce the potential yield, thus threatening food security. This study evaluated compounds from Hagenia abyssinica for bioactivity against bean bacterial pathogens Xanthomonus axonopodis pv. phaseoli and Pseudomonus savastanoi pv. phaseolicola. One triterpenoid, 1,3,19-trihydroxy-2-oxo-12-ursen-28-oic acid (1) and two flavans namely, 3,3’,4’,5’-tetrahydroxyflavan (2) and 3,3’,4’,5,7-pentahydroxyflavan (3) were isolated from the bark of H. abyssinica. Structures of the compounds were elucidated based on nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectra (HRESIMS) data analysis. These compounds and the ethyl acetate extract were evaluated against the bean pathogens using agar disc diffusion method. The ethyl acetate crude extract showed activity against the two pathogens with minimum inhibitory concentrations of 1.25 mg/mL. Compound 1 showed good activity against X. axonopodis pv. phaseoli and P. savastanoi pv. phaseolicola with minimum inhibitory concentrations of 5 and 1.25 mg/mL, respectively, whereas compounds 2 and 3 showed modest activity. This study demonstrated that compound 1 and the ethyl acetate crude extract from H. abyssinica have good activity against the two bean pathogens and can be used in the development of biopesticides to control bean diseases.   Key words: Bean pathogens, bioactive compounds, Hagenia abyssinica, Xanthomonus axonopodis pv. phaseoli, Pseudomonus savastanoi pv. phaseolicola.

Synthesis, experimental and molecular dynamics simulation of the ESI-CID spectrum of the nerve agent Novichok analog O-2-methoxyethyl N- [bis(dimethylamino)methylidene]-P-methylphosphonamidate

The comprehensive and accurate analysis of mass spectral data is critical for the unequivocal identification of environmental samples containing compounds short-listed by the Chemical Weapons Convention (CWC). In particular, experiments with nerve agents are limited by the high risks involved in their handling. Therefore, the possibility of studying fragmentation pathways by a theoretical approach is especially welcome. In this work, for the first time, O-2-methoxyethyl N- [bis(dimethylamino)methylidene]-P-methylphosphonamidate, an analog of the Novichok nerve agent A-242, was synthesized employing a one-pot microscale synthesis. Electron ionization (EI) and electrospray ionization (ESI) mass spectra (MS) were measured to provide data for CWC verification purposes. Considering that ESI-MS/MS is a powerful method for analyzing non-volatile, highly polar, and very water-soluble compounds, such as degradation products of nerve agents, we extensively investigated for the first time the ESI-(collision-induced dissociation) CID fragmentation pathways of the selected molecule. For this purpose, molecular dynamics simulations using the Quantum Chemical Mass Spectrometry (QCxMS) method employing the semiempirical electronic structure method GFN2-xTB were compared with Triple Quadrupole electrospray ionization (ESI) experimental spectra in positive ion mode. The base peak of the EI spectrum for this molecule was found to be m/z 151, which strongly suggests a McLafferty +1 (ML+1) rearrangement involving the 2-methoxyethyl moiety. The formation of ion the m/z 106 in the ESI-CID spectrum, according to the simulations, results from the rearrangement involving a transfer of one dimethylamino group to the phosphorus atom, a mechanism that would be difficult to identify without employing theoretical methods.