Investigation of Euphrasia rostkoviana Hayne Using GC–MS and LC–MS

Gas and liquid chromatography coupled with mass spectrometry was applied to solve difficulties and reinvestigate the serious matrix problems affecting analysis of the active compounds in Euphrasia rostkoviana Hayne. The main groups of compounds were obtained by extracting the herb stepwise with n-hexane, chloroform, ethyl acetate and methanol. Polyamide column chromatography facilitated further separation. Phenolic/flavonoid- and terpenoid-type molecules were studied by GC–MS, HPLC and LC–MS–MS. The β-sitosterol content of the herb was determined by gas chromatography with flame ionisation detection (GC-FID). Caffeic acid, chlorogenic acid, coumaric acid and flavonoid glycosides of apigenin, luteolin, rhamnetine (hexoside), kaempferol (both hexoside and rutinoside) and quercetin (rutinoside) were identified in the fractions of the methanolic extract.     

New routes to the preparation of <Emphasis Type="Italic">gem</Emphasis>-cyclopentenedicarboxylic acid derivatives

A new route was developed to design esters of gem-dicarboxylic acids of cyclopentene series by CH alkylation of diethyl malonate with cis-1,4-dichlorobutene. Diethyl cyclopent-3-ene-1,1-dicarboxylate was reacted with dichlorocarbene. The structures of the isolated compounds were described in detail by ¹H, ¹³C NMR spectroscopy and GC–MS.     

From individual proteins to proteomic samples: characterization of <Emphasis Type="Italic">O</Emphasis>-glycosylation sites in human chorionic gonadotropin and human-plasma proteins

O-glycosylation-site characterization of individual glycoproteins is a major challenge because of the heterogeneity of O-glycan core structures. In proteomic studies, O-glycosylation-site analysis is even more difficult because of the complexity of the sample. In this work, we designed a rapid and convenient workflow for characterizing the O-glycosylation sites of individual proteins and the human-plasma proteome. A mixture of exoglycosidases was used to partially remove O-glycan chains and leave an N-acetylgalacosamine (GalNAc) residue attached to the Ser or Thr residues. The O-glycosylated peptides could then be identified by using liquid chromatography–tandem mass spectrometry (LC–MS–MS) to detect the 203 Da mass increase. Jacalin was used to selectively isolate O-GalNAc glycopeptides before LC–MS–MS analysis, which is optional for individual proteins and necessary for complex human-plasma proteins. Bovine fetuin and human chorionic gonadotropin (hCG) were used to test the analytical workflow. The workflow indicated superior sensitivity by not only covering most previously known O-glycosylation sites but also discovering several novel sites. Using only one drop of blood, a total of 49 O-GalNAc-linked glycopeptides from 36 distinctive glycoproteins in human plasma were identified unambiguously. The approach described herein is simple, sensitive, and global for site analysis of core 1 through core 4 O-glycosylated proteins.     

Green Synthesis of Silver Nanoparticles Using <Emphasis Type="Italic">Commiphora caudata</Emphasis> Leaves Extract and the Study of Bactericidal Efficiency

The present study reports the synthesis of silver nanoparticles (Ag NPs) from silver nitrate solution using leaf extracts of Commiphora caudata. The formation of Ag NPs in the colloidal solution is confirmed by UV–Vis spectroscopy analysis. The identification of biomolecules is analyzed through fourier transform infrared spectroscopy. X-ray diffraction pattern shows that an average particle size of the synthesized nanoparticles are in the range of 40–24 nm. Field emission scanning electron microscopy and transmission electron microscopy confirm the formation Ag NPs in spherical shape. The photoluminescence study of the synthesized Ag NPs interprets the influence of C caudata leaf concentrations on emission behavior. Zeta potential measurement is carried out to determine the stability of synthesized Ag NPs. GC–MS analysis revealed that the C. caudata contained 11 compounds, such as Stigmasterol (24.14 %), Hexacosanoic acid, methyl ester (15.13 %) and 2-bromophenyl morpholine-4-carboxylate (11.71 %). The antibacterial activity of Ag NPs shows that these bio capped Ag NPs have higher inhibitory action for Escherichia coli, Klebsiella pheumoniea, Micrococcus flavus, Pseudomonas aeruginosa, Bacillus subtilis, Bacillus pumilus, Staphylococcus aureus.     

Metabolomic Analysis of the Lichen <Emphasis Type="Italic">Everniopsis trulla</Emphasis> Using Ultra High Performance Liquid Chromatography-Quadrupole-Orbitrap Mass Spectrometry (UHPLC-Q-OT-MS)

A new depside was identified in the methanolic extract from the lichen Everniopsis trulla based on the metabolomics UHPLC–DAD–MS analysis and HESI–MS–MS fragmentation patterns along with thirty-two known compounds for the first time. The compounds were structurally characterized by UV and high resolution quadrupole orbitrap mass spectra and by comparison with literature. According to the characteristic fragmentation patterns, the presence of two simple aromatic compounds, six lipid derivatives, eight depsidones, thirteen depsides, a chromone, two diphenylethers, and a dibenzofuran were identified. To our knowledge, this is the first study of the lichen E. trulla by liquid chromatography hyphenated with tandem mass spectrometry.     

Effect of Plant Growth Promoting Bacteria Associated with Halophytic Weed (<Emphasis Type="Italic">Psoralea corylifolia</Emphasis> L) on Germination and Seedling Growth of Wheat Under Saline Conditions

Halotolerant bacteria associated with Psoralea corylifolia L., a luxuriantly growing annual weed in salinity-affected semi-arid regions of western Maharashtra, India were evaluated for their plant growth-promoting activity in wheat. A total of 79 bacteria associated with different parts viz., root, shoot and nodule endophytes, rhizosphere, rhizoplane, and leaf epiphytes, were isolated and grouped based on their habitat. Twelve bacteria isolated for their potential in plant growth promotion were further selected for in vitro studies. Molecular identification showed the presence of the genera Bacillus, Pantoea, Marinobacterium, Acinetobacter, Enterobacter, Pseudomonas, Rhizobium, and Sinorhizobium (LC027447-53; LC027455; LC027457, LC027459, and LC128410). The phylogenetic studies along with carbon source utilization profiles using the Biolog® indicated the presence of novel species and the in planta studies revealed promising results under salinity stress. Whereas the nodule endophytes had minute plant growth-promoting (PGP) activity, the cell free culture filtrates of these strains enhanced seed germination of wheat (Triticum aestivum L). The maximum vigor index was monitored in isolate Y7 (Enterobacter sp strain NIASMVII). Indole acetic acid (IAA) production by the isolates ranged between 0.22 and 25.58 μg mL^?1. This signifies the need of exploration of their individual metabolites for developing next-generation bio-inoculants through co-inoculation with other compatible microbes. This study has potential in utilization of the weed-associated microbiome in terms of alleviation of salinity stress in crop plants.     

Precursor Ion-Scan Mode-Based Screening Strategy for New Amorfrutin Derivatives from <Emphasis Type="Italic">Amorpha fruticosa</Emphasis> by UPLC–QqQ–MS and UPLC–Q-TOF–MS

This study presents a screening strategy for unknown compounds by coupling UPLC–QqQ–MS and UPLC–Q-TOF–MS analyses. Amorfrutins, potential PPARγ agonists in Amorpha fruticosa, were selected as the research target. First, MS/MS analysis of three amorfrutin references (AA, AB, and AC) by Q-TOF revealed the mass-spectrometric fragmentation patterns of amorfrutins, and m/z 225 was recognized as a characteristic and common fragment ion of amorfrutins. Then, unknown amorfrutins were screened in the fruits of A. fruticosa by UPLC–QqQ–MS operating in precursor ion-scan mode, and the product ion was set as m/z 225 for screening potential amorfrutins. According to the high-resolution MS–MS spectral data provided by UPLC–Q-TOF–MS, the molecular formula of potential amorfrutins and their respective characteristic fragments were calculated. Finally, three unknown amorfrutins, namely, amorfrutin D and two new amorfrutins, were identified. As far as we know, this is the first study to rapidly identify unknown compounds by combined application of QqQ–MS precursor ion scan and Q-TOF–MS formula calculation. This research strategy will also be effective for the discovery of other trace natural products and metabolites.     

Modification of silica nanoparticles with stereisomers of <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-butylthiacalix[4]arene containing four 2-oxo-2-{[3-(triethoxysilyl)prop-1-yl]amino}ethoxy substituents at the lower rim

Three stereoisomers (cone, partial cone, and 1,3-alternate) of p-tert-butylthiacalix[4]arene bearing four anchor propyltriethoxysilane substituents at the lower rim were synthesized for the first time. Surface modification of silica nanoparticles (d = 12 nm) with the synthesized macrocycles gave novel hybride thiacalix [4]arene?SiO₂ particles. The obtained nanostructured adsorbents were found to efficiently extract nitroaromatic compounds from aqueous solutions. The partial cone and 1,3-alternate thiacalix[4]arene–SiO₂ hybrid particles showed affinity to nitrophenols.     

Platinum precursor of anticancer drug: a structure fixed by long intermolecular N–H···I and C–H···I hydrogen bonds

The title compound 1, cis-[diiodo(1R,2R)-1,2-diaminocyclohexane-κN,κN′]platinum(II), a precursor of a novel platinum-based anticancer complex, was synthesized. High purity (>99%) was determined by HPLC–UV/VIS and its structure was characterized by LC–ESI–MS, FT-IR and X-ray single-crystal diffraction. The molecules of the title compound interact via N–H···I and C–H···I intermolecular (ultra)-long hydrogen–iodine (acceptor) bonds (distances up to 3.1 Å). The crystal structure of the title compound 1 was compared to the structure calculated on the basis of density function theory (DFT). The calculated and measured data varied by a maximum of 0.09 Å in bond lengths and the maximum deviation between the compared angles were less than 2°. Experimentally measured bond lengths in the crystal were observed to be reduced when compared to the theoretical calculation. This was caused by both steric requirements of individual structural units and the presence of hydrogen bonds in real sample, which were confirmed by FT-IR (new bands as well as the band shifts to lower wavelengths).     

Quantitative analysis of amphiphilic <Emphasis Type="Italic">N</Emphasis>-alkyloxypyridinecarboximidamide by liquid chromatography–tandem mass spectrometry

LC–MS/MS method to determine hydrophobic N-alkyloxy substituted amidines: N-(2-ethylhexyloxy)pyridine-2-carboximidamide, N-(2-ethylhexyloxy)pyridine-3-carboximidamide, N-(2-ethylhexyloxy)pyridine-4-carboximidamide, N-decyloxy pyridine-2-carboximidamide, N-decyloxypyridine-3-carboximidamide and N-decyloxypyridine-4-carboximidamide was developed and validated in terms of linearity, precision and accuracy. The developed method was successfully applied to monitor and control the synthesis process. The experimental data points indicated that the straight chain alkyl bromide reacted most rapidly than branched alkyl bromide and the enhancement of the reaction efficiency strongly depended on reaction temperature.     

Synthesis of Boron-Containing Siloxanes by Reaction of Hydroxy-<Emphasis Type="Italic">closo</Emphasis>-Decaborates with Dihalosilanes

A new approach to the preparation of boron-containing siloxanes based on cluster boron anions has been suggested. This approach consists in the reaction of hydroxy derivatives of closo-decaborate anion [B₁₀H_10–n(OH)_n]^2– (n = 1, 2) with dihalosilanes SiR₂Cl₂ (R = CH₃, _t- C₄H₉, C₆H₅). The obtained compounds have been characterized by IR, ESI/MS, and NMR (1H, 11B, 13C) spectroscopy.     

Rearrangements of <Emphasis Type="Italic">N</Emphasis>-ethoxycarbonylmethyl-1,2,3,4-tetrahydroquinolinium halogenalkylates effected by sodium hydride. Synthesis of 2,3,4,5-tetrahydro-1<Emphasis Type="Italic">H</Emphasis>-3-benzazepines

Quaternary salts obtained from N-alkyl-1,2,3,4-tetrahydroisoquinolines and ethyl haloacetates or diethyl bromomalonate under the action of sodium hydride in boiling 1,4-dioxane were converted into N-alkyl-N-ethoxycarbonyl-2,3,4,5-tetrahydro-1H-3-benzazepines in 49–60% yield. From the reaction mixture by column chromatography products of β-elimination by Hofmann reaction, 2-(N-methyl-N-ethoxycarbonylmethyl)-aminomethylstyrenes were also isolated (yield 0.6–16%).     

Synthesis of amino acid conjugates of glycyrrhizic acid using <Emphasis Type="Italic">N</Emphasis>-hydroxyphthalimide and <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>'-dicyclohexylcarbodiimide

Synthesis of amino acid conjugates of glycyrrhizic acid with the use of N-hydroxyphthalimide, N,N'-dicyclohexylcarbodiimide, and tert-butyl esters of L-amino acids (valine, isoleucine, phenylalanine, and methionine) was performed followed by deprotection with trifluoroacetic acid. The target amino acid conjugates were isolated by column chromatography on silica gel in 40–45% yield. The structure of the prepared compounds was confirmed by IR and ¹³C NMR spectroscopy.     

Dicarboxylic acids and hydroxy fatty acids in different species of fungi

Secondary metabolites of fungi can be responsible for allergies; therefore, the identification of compounds produced by these organisms is very important. Fungi produce large amounts of secondary metabolites, which belong to groups of chemicals such as: dicarboxylic acids, hydroxy acids, alcohols, hydrocarbons, esters, fatty acids, sterols, amino acids and mycotoxins. The presence of all these compounds in human proximity contributes to many diseases. Therefore, the aim of the study was a qualitative and quantitative analysis of hydroxy and dicarboxylic acids produced by fungi occurring in student hostel in Poland, in the province of Pomerania. The following species of fungi were subjected to extraction: Aspergillus niger, Aspergillus fumigatus, Aspergillus candidus, Rhizopus sp., Geotrichum candidum, and Penicillium chrysogenum. A mixture of ethyl acetate and methanol was used for the extraction. The obtained extracts were further analyzed by gas chromatography mass spectrometry (GC–MS). In all samples of fungi, the presence of a total of 22 acids, including 13 dicarboxylic and 9 hydroxy acids, was confirmed. Most acids (17 different acids) were identified in A. fumigatus. Only 10 acids were identified in the mycelium of G. candidum and A. niger. Acids which were identified in all samples of the mycelium were 22-hydroxydocosanoic acid, 24-hydroxytetracosanoic acid and adipic acid. The most abundant compounds were 22-hydroxydocosanoic acid in A. fumigatus, A. candidus, Rhizopus sp., G. candidum and P. chrysogenum, and succinic acid in A. niger. More experiments are needed to understand the physiological role of hydroxy and dicarboxylic acids. We hope that our results are an important contribution to further studies on the human health.     

Fragmentation of Protonated <Emphasis Type="Italic">N</Emphasis>-(3-Aminophenyl)Benzamide and Its Derivatives in Gas Phase

An ion of m/z 110.06036 (ion formula [C₆H₈NO]⁺; error: 0.32 mDa) was observed in the collision induced dissociation tandem mass spectrometry experiments of protonated N-(3-aminophenyl)benzamide, which is a rearrangement product ion purportedly through nitrogen-oxygen (N–O) exchange. The N–O exchange rearrangement was confirmed by the MS/MS spectrum of protonated N-(3-aminophenyl)-O ¹⁸ -benzamide, where the rearranged ion, [C₆H₈NO ¹⁸ ]⁺ of m/z 112 was available because of the presence of O ¹⁸ . Theoretical calculations using Density Functional Theory (DFT) at B3LYP/6-31 g(d) level suggest that an ion-neutral complex containing a water molecule and a nitrilium ion was formed via a transition state (TS-1), followed by the water molecule migrating to the anilide ring, eventually leading to the formation of the rearranged ion of m/z 110. The rearrangement can be generalized to other protonated amide compounds with electron-donating groups at the meta position, such as, –OH, –CH₃, –OCH_3, –NH(CH₃)₂, –NH-Ph, and –NHCOCH₃, all of which show the corresponding rearranged ions in MS/MS spectra. However, the protonated amide compounds containing electron-withdrawing groups, including –Cl, –Br, –CN, –NO₂, and –CF₃, at the meta position did not display this type of rearrangement during dissociation. Additionally, effects of various acyl groups on the rearrangement were investigated. It was found that the rearrangement can be enhanced by substitution on the ring of the benzoyl with electron-withdrawing groups.

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Microbial Transformation of Curcumin to Its Derivatives with a Novel <Emphasis Type="Italic">Pichia kudriavzevii</Emphasis> ZJPH0802 Strain

Curcumin, a polyphenolic compound, has shown a wide range of pharmacological activities and has been widely used as a food additive. However, the clinical use of curcumin is limited to some extent because of its poor water solubility and low bioavailability. To overcome these problems, many approaches have been attempted and structural modification of curcumin by microbial transformation has been proven to be an alternative. In this study, we isolated a novel yeast strain Pichia kudriavzevii ZJPH0802 from a soil sample, which is capable of converting curcumin to its derivatives. The transformed products by this strain were evaluated by HPLC, (+) electrospray ionization (ESI)-MSⁿ, and ¹H nuclear magnetic resonance methods. Compared with controls, two new peaks of the transformed broth appeared at retention times of 26 min (I) and 62 min (II) by HPLC analysis. The two transformed products were then further identified by (+) ESI-MSⁿ. The spectrum showed that compound I had an accurate [M+H+NH₃]⁺ ion at m/z 392, [M+H]⁺ ion at m/z 375, [M+H–H₂O]⁺ ion at m/z 357, and (+) ESI-MS³ spectrum showed that ion at m/z 357 could further form fragment ions at m/z 339, 177, and 163; compound II had an accurate [M+H]⁺ ion at m/z 373, [M+H–H₂O]⁺ ion at m/z 355, and (+) ESI-MS³ spectrum showed that ion at m/z 355 could further form fragment ions at m/z 219, 179, 177, 163, and 137. These two transformed products thereby were confirmed as hexahydrocurcumin (I) and tetrahydrocurcumin (II).     

Resolving the Discrepancies Between Empirical and Rayleigh Charge Limiting Models for Globular Proteins

Starting with the Rayleigh charge limiting model, a slightly different approach is used to account for the well-known discrepancy that exists between the said model and experimental ESI MS data for globular proteins. It is shown using published datasets that for globular proteins, the mass density ρ exhibits a weak second-order dependence on its mass M, according to ρ(M)∝ M^-α, α ~ 0.14. A direct equivalence established between ESI MS and x-ray techniques suggests a minimum but critical surface tension of 15.6?±?5.2 mN/m for the droplet at the liquid-to-gas phase transition point. The packing density factor η for globular proteins is believed to lie between 1 (very tightly packed) and 4.6 (less tight, natively packed). While the Rayleigh charge limiting model has been linked historically to the CRM (J. Chem. Phys. 49:2240–2249, 1968; Anal. Chim. Acta 406:93–104, 2000), this paper does not expressly seek to justify the CRM, but rather uses empirical data and existing knowledge across subfields to help build a consistent picture of ESI MS phenomena that might be difficult to explain otherwise. These results would be useful in molecular dynamics (MD) simulations, understanding liquid-to-gas phase transitions and in opening up new routes for cross-calibration between ESI MS, IM MS, NMR and x-ray crystallography studies.

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Potentiality of independent component regression in assessment of the peaks responsible for antimicrobial activity of <Emphasis Type="Italic">Satureja hortensis</Emphasis> L. and <Emphasis Type="Italic">Oliveria decumbens</Emphasis> Vent. using GC–MS

Satureja hortensis L. and Oliveria decumbens Vent. are used in traditional medicine in the world due to its antifungal, antibacterial and antioxidant properties. In this study, the antimicrobial activities in Satureja hortensis L. and Oliveria decumbens Vent. essential oils against three microbial strains were evaluated by two different methods, including: disk diffusion method and micro-broth dilution assay [with minimal inhibitory concentration (MIC) between 0.025 and 0.500 µL/mL, and minimal lethal concentration (MLC) between 0.050 and 1.000 µL/mL] and qualitative analysis was performed by gas chromatography–mass spectrometry technique (GC–MS). The peaks potentially responsible for the antimicrobial activity in essential oils samples were indicated by some linear multivariate calibration techniques with different preprocessing methods. From the studied techniques, independent component regression (ICR) was preferred to exhibit the potential antimicrobial active compounds in Satureja hortensis L. and Oliveria decumbens Vent. essential oils because of its high repeatability, simplicity, and interpretability of the regression coefficients. Independent components (ICs) can give more chemical explanation than principal components (PCs), because independence is a high-order statistic that is a much stronger condition than orthogonality.     

The Role of Temperature in Enantioseparation of Norgestrel with Native Cyclodextrins: A Combined LC and NMR Study

Temperature dependence (10–50 °C) of the chiral LC separation of norgestrel was studied using native CDs added to a methanol–water 1:1 eluent. α- or β-CDs gave no enantiodiscrimination, while baseline LC separation was achieved with γ-CD. ¹H NMR titrations of the racemate with α-CD showed only weak complexation, while β- or γ-CDs caused enantiomeric splitting of the steroid signals. Both the chiral selectivity values and their insignificant temperature dependence measured in the γ-CD-modified LC system were successfully reproduced by NMR titrations. This agreement corroborates the intuitive view for a wider temperature range that the stability difference of the diastereomeric γ-CD/steroid complexes governs this LC enantioseparation.