High Performance Liquid Chromatography-high Resolution Mass Spectrometry Research Articles

Effect of modifiers on the stability of 1‑butyl‑3-methylimidazolium-based ionic liquids

The distinctive capabilities of 1‑butyl‑3-methylimidazolium (bmim) cation-based ionic liquids (ILs) to dissolve lignocellulosic biomass offer the potential for the development of novel green bioprocessing technologies based on their utilization as green solvents. The limited range of thermal stability of ILs necessitates the use of various co-solvents to maintain solubility. In the present study, an original approach to determine the degree of degradation of alkylimidazolium ILs was proposed, based on the application of gravimetric analysis method to determine the content of volatile degradation products and high-performance liquid chromatography-high-resolution mass spectrometry (HPLCHRMS) to determine the total degree of degradation. The proposed approach, as well as the combination of HPLCHRMS with gas chromatography-mass spectrometry (GC–MS), was employed to comprehensively characterize the impact of additives and impurities (water, dimethyl sulfoxide, hydrochloric and acetic acids, diethylamine) on the degradation of bmim acetate, chloride, and methyl sulfate during thermal treatment under typical biomass dissolution conditions (150 °C, 24 h). The presence of additives or impurities in the composition of ILs has been found to predominantly contribute to a decrease in the number of volatile compounds formed, while increasing the variety and relative content of non-volatile degradation products. The use of protic solvents and acids results in a decrease in the overall degree of degradation of ionic liquids and in the fraction of volatile compounds formed. This allows for the classification of binary mixtures based on these additives as "green" solvents at temperatures below 150 °C.

Nontargeted Analysis of Reactive Nitrogenous Compounds in Suwannee River Standard Reference Materials and Authentic River Water Samples.

Concerns over toxic nitrogenous disinfection byproducts (N-DBPs) necessitate identifying their precursors in source water. Natural organic amino compounds are known precursors to N-DBPs. Three Suwannee River (SR) standard reference materials (SRMs), humic acids (HA), fulvic acids (FA), and natural organic matter (NOM), are commonly used to study DBP formation, but the chemical makeup of amino compounds in SRSRMs remains largely unknown. To address this, we combined stable hydrogen/deuterium isotope labeling, HDPairFinder bioinformatics, and nontargeted high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS) to characterize these compounds in SRSRMs. This method classifies reactive amines, provides accurate masses and MS/MS spectra, and quantifies intensities. We identified 2707 high-quality features with primary and/or secondary amines in SRSRMs and 75% of them having an m/z < 300. Across all three SRSRMs, 327 amino features were detected, while 856, 794, and 200 unique features were found in SRNOM, SRHA, and SRFA, respectively. In North Saskatchewan River (NSR) samples, a total of 6449 amino features were detected, 818 of them matched those in SRSRMs, and 87% of them were different between the two rivers. Using chemical standards, we confirmed 10 compounds and tentatively identified 5 more. This study highlights similarities and differences in reactive N-precursors in SRSRMs and local river water, enhancing the understanding of geo-differences in reactive N-precursors in different source waters.

Simultaneous detection of 10 cancer-associated amino acids and polyamines by high-performance liquid chromatography-high resolution mass spectrometry in pleural effusion cells obtained from lung adenocarcinoma patients

The deregulation of amino acid and polyamine metabolism is a hallmark of malignancy that regulates cancer cell proliferation, angiogenesis, and invasion. A sensitive mass spectrometry method was developed to simultaneously quantify 10 cancer-associated metabolites in pleural effusion cells for the diagnosis of malignancy and to complement conventional pleural cytology. Analytes were detected by high-performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) using C8-reversed-phase HPLC for separation and sequential window acquisition of all theoretical fragment ion spectra (SWATH) acquisition for obtaining high-resolution quantitative MS/MS chromatograms. This method was validated and applied to pleural effusion cells from patients with lung adenocarcinoma (LUAD, n = 48) and those from benign controls (n = 23). The range of the above metabolites was 2–200 ng/mL for proline, aspartate, ornithine, creatine, glutamine, glutamate, arginine, citrulline, and spermine and 10–1000 ng/mL for putrescine. The intra-assay and inter-assay coefficient of variation was below 13.70 % for all analytes. The joint detection of these metabolites in pleural effusion cells achieved a clinical sensitivity of 75.0 % and specificity of 95.7 % differentiating LUAD patients from benign controls. This assay enabled the detection of 10 cancer-associated metabolites in pleural effusion cells, and the increased concentration of these metabolites was correlated with the presence of LUAD.

Unveiling the fungal diversity and associated secondary metabolism on black apples.

Black apples are the result of late-stage microbial decomposition after falling to the ground. This phenomenon is highly comparable from year to year, with the filamentous fungus Monilinia fructigena most commonly being the first invader, followed by Penicillium expansum. Motivated by the fact that only little chemistry has been reported from apple microbiomes, we set out to investigate the chemical diversity and potential ecological roles of secondary metabolites (SMs) in a total of 38 black apples. Metabolomics analyses were conducted on either whole apples or small excisions of fungal biomass derived from black apples. Annotation of fungal SMs in black apple extracts was aided by the cultivation of 15 recently isolated fungal strains on 9 different substrates in a One Strain Many Compounds (OSMAC) approach, leading to the identification of 3,319 unique chemical features. Only 6.4% were attributable to known compounds based on analysis of high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS/MS) data using spectral library matching tools. Of the 1,606 features detected in the black apple extracts, 32% could be assigned as fungal-derived, due to their presence in the OSMAC-based training data set. Notably, the detection of several antifungal compounds indicates the importance of such compounds for the invasion of and control of other microbial competitors on apples. In conclusion, the diversity and abundance of microbial SMs on black apples were found to be much higher than that typically observed for other environmental microbiomes. Detection of SMs known to be produced by the six fungal species tested also highlights a succession of fungal growth following the initial invader M. fructigena.IMPORTANCEMicrobial secondary metabolites constitute a significant reservoir of biologically potent and clinically valuable chemical scaffolds. However, their usefulness is hampered by rapidly developing resistance, resulting in reduced profitability of such research endeavors. Hence, the ecological role of such microbial secondary metabolites must be considered to understand how best to utilize such compounds as chemotherapeutics. Here, we explore an under-investigated environmental microbiome in the case of black apples; a veritable "low-hanging fruit," with relatively high abundances and diversity of microbially produced secondary metabolites. Using both a targeted and untargeted metabolomics approach, the interplay between metabolites, other microbes, and the apple host itself was investigated. This study highlights the surprisingly low incidence of known secondary metabolites in such a system, highlighting the need to study the functionality of secondary metabolites in microbial interactions and complex microbiomes.

Conversion of estriol to estrone: A bacterial strategy for the catabolism of estriol

Natural estrogens, including estrone (E1), 17β-estradiol (E2), and estriol (E3), are potentially carcinogenic pollutants commonly found in water and soil environments. Bacterial metabolic pathway of E2 has been studied; however, the catabolic products of E3 have not been discovered thus far. In this study, Novosphingobium sp. ES2-1 was used as the target strain to investigate its catabolic pathway of E3. The metabolites of E3 were identified by high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) combined with stable 13C3-labeling. Strain ES2-1 could almost completely degrade 20 mg∙L-1 of E3 within 72 h under the optimal conditions of 30°C and pH 7.0. When inoculated with strain ES2-1, E3 was initially converted to E1 and then to 4-hydroxyestrone (4-OH-E1), which was then cleaved to HIP (metabolite A6) via the 4, 5-seco pathway or cleaved to the B loop via the 9,10-seco pathway to produce metabolite with a long-chain ketone structure (metabolite B4). Although the ring-opening sequence of the above two metabolic pathways was different, the metabolism of E3 was achieved especially through continuous oxidation reactions. This study reveals that, E3 could be firstly converted to E1 and then to 4-OH-E1, and finally degraded into small molecule metabolites through two alternative pathways, thereby reducing E3 pollution in water and soil environments.

Development and validation of rapid screening of 192 veterinary drug residues in aquatic products using HPLC-HRMS coupled with QuEChERS

The presence of veterinary drug residues in aquatic products represents a significant challenge to food safety. The current detection methods, limited in both scope and sensitivity, underscore the urgent need for more advanced techniques. This research introduces a swift and potent screening technique using high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS) and a refined QuEChERS protocol, allowing simultaneous qualitative and semi-quantitative analysis of 192 residues. A comprehensive database, employing full scan mode and data-dependent secondary mass spectroscopy, enhances screening accuracy. The method involves efficient extraction using 90% acetonitrile, dehydration with Na2SO4, and acetic acid, followed by cleanup using dispersive solid-phase extract sorbent primary secondary amine. It is suitable for samples with varying fat content, offering detection limits ranging from 0.5 to 10 μg/kg, high recovery rates (60–120%), and low relative standard deviations (<20%). Practical application has validated its effectiveness for multi-residue screening, marking a significant advancement in food safety evaluation.

Evaluation of the toxicological effects of Neltuma alpataco (Prosopis alpataco) pod alkaloid extract

The pods of Neltuma spp. have shown potential as a source of protein and energy in livestock. However, prolonged consumption of some of these species can lead to neurological symptoms in ruminants. This study aimed to determine the alkaloid content, as well as the in vitro and in vivo effects of an alkaloid-enriched extract (AEE) from N. alpataco pods. High performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) identified juliprosine and juliprosopine as primary alkaloids, with juliprosine being most abundant. AEE from N. alpataco demonstrated dose-dependent cytotoxicity on glioma cells after 48 h, with a 50% cytotoxic concentration (CC50) of 24.69 μg/mL. However, the release of LDH was observed only at the highest tested concentration, indicating cellular damage. Further examination through phase-contrast microscopy and dual acridine orange/ethidium bromide fluorescence staining revealed morphological changes consistent with an apoptotic mechanism of cell death, ultimately leading to secondary necrosis. Finally, the LD50 after intraperitoneal injection in mice was determined to be 12.98 mg/kg. Taken together, these findings demonstrated for the first time the in vivo and in vitro toxicity of the AEE from N. alpataco pods.

Study on the production of Sophorolipid by Starmerella bombicola yeast using fried waste oil fermentation.

Sophorolipids (SLs) are surface active compounds that have excellent surface-lowering properties. SLs were produced by Starmerella bombicola (CGMCC1576) yeast with sunflower seed oil, fried waste oil, cooked tung oil and raw tung oil used as hydrophobic carbon sources. The results showed that the strain could use sunflower seed oil and fried waste oil as hydrophobic carbon sources to produce SLs, and the yields were 44.52 and 39.09 gl-1. It could not be used as cooked tung oil and raw tung oil. The analysis by high-performance liquid chromatography/high resolution mass spectrometry (HPLC-MS/MS) showed that the main composition and structure of SLs produced by fermentation using fried waste oil were similar to that of sunflower seed oil as hydrophobic carbon source. The yield of SLs was the highest when the fried waste oil was used as hydrophobic carbon source, glucose (8%), waste oil (6%) and yeast (0.3%). When fried waste oil was used as a hydrophobic carbon source in a parallel 4-strand fermentation tank (FT), the combination with the largest yield and the most cost saving was that 3% of fried waste oil was added into the initial medium, and another 3% was again added after 72 h of fermentation. The total yield of SLs was 121.28 gl-1, and the yield of lactone SLs was 48.07 gl-1.

Identification of thermolabile positional isomers of N-(2-hydroxybenzyl)-2-(dimethoxyphenyl)ethanamines (NBOH series) using chromatography and mass spectrometry methods.

Among N-((2-substituted)benzyl)phenylethanamines, N-(2-hydroxybenzyl)phenylethanamines are a special type of compounds which are thermolabile and degrade in the course of analysis by means of gas chromatography-mass spectrometry (GC-MS). This can lead to substantial errors, in the identification of legally controlled compounds of this series containing methoxy groups at positions 2 and 5 of the benzene ring of the phenylethyl fragment by GC-MS, which is commonly used in forensic and toxicological laboratories. Exemplified by the five isomeric 2-(dimethoxyphenyl)-N-(2-hydroxybenzyl)ethanamines, it was shown that their derivatization with trifluoroacetic anhydride (same as in the case of the N-(2-methoxybenzyl)-, N-(2-fluorobenzyl)-, N-(2-chlorobenzyl)-, and N-(2-bromobenzyl)substitutes phenylethanamines [NBOMe, NBF, NBCl, and NBBr, respectively] series described earlier) results in only one product, N-monosubstituted derivative, for each positional isomer within a series, which makes it possible to reliably identify each compound by the GC-MS method. In addition, chromatographic conditions for sufficient separation of trifluoroacetyl derivatives of these positional isomers of the NBOH series in 25 min are proposed, which is an important aspect for analysis in forensic laboratories engaged in the determination of narcotic drugs and new psychoactive substances. As an alternative approach, a method for identifying positional isomers of the NBOH series by the high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS) method without derivatization is proposed.

Chemical Profiling on Bioactive Stilbenoids in the Seeds of Paeonia Species Growing Wild in Greece

The seeds of Paeonia clusii Stern subsp. clusii and Paeonia mascula (L.) Mill. subsp. mascula growing wild in Greece, though not previously investigated, has been studied as a source of bioactive stilbenoids and other phenolics. Their methanol extracts were analyzed using ultra high-performance liquid chromatography—high-resolution mass spectrometry (UHPLC-HRMS), and among the identified metabolites (62), 19 paeoniflorin’s derivatives, 17 flavonoids and 12 stilbenes were detected. Moreover, through classic phytochemical separation procedures, twelve among them were isolated and fully spectrally determined as trans-resveratrol, trans-resveratrol-4′-O-β-D-glucopyranoside, cis-resveratrol-4′-O-β-D-glucopyranoside, trans-gnetin-H, trans-ε-viniferin, luteolin, luteolin-3′-O-β-D-glucopyranoside, luteolin-3′,4′-di-O-β-D-glucopyranoside, apigenin, hispidulin, paeoniflorin and benzoyl-paeoniflorin. All seed extracts were measured for their total phenolic content (TPC), appearing as a rich source (116.04 and 103.63 mg GAE/g extract, respectively), followed by free radical (DPPH) scavenging capacity (75.24% and 91.54% inhibition at the concentration of 200 μg/mL). The evaluation of tyrosinase inhibition for both extracts (61% and 70%, respectively) confirmed the potential for their future application in skin health care, comparable with other paeonies of Chinese origin, which are well-known as skin whitening and anti-aging promoters.

Stabilization of N-terminal cysteines in HPLC-HRMS quality control of peptide pools

Abstract Synthetic peptide pools are used in experimental and clinical immunology, for example, cancer immunotherapy. The analytical characterization is challenging due to the similarity of the peptides, usually only a pre-characterization of the single peptides is performed. However, regular quality control of the peptide mix would be highly desirable. Therefore, a high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS) method for quality control of a peptide pool was developed. Peptides were synthesized and purified to &amp;gt; 90% each. The lyophilized single peptides were combined to a peptide pool containing 32 peptides and analyzed by HPLC-HRMS. Quantification is carried out UV detection, and identification is obtained by high resolution mass spectrometry. Before separation on a capillary reversed-phase column, alkylation of thiols was performed. Best results were obtained with a linear gradient from 96% of solvent A (water with 0.05% TFA), 4% of solvent B (acetonitrile with 0.04% TFA) to 56% of solvent A, 44% of solvent B in 100 minutes. Without sample preparation, peptides with N-terminal cysteine will yield almost no UV signal. This surprising effect could be eliminated using iodoacetic acid (IAC) as an alkylation reagent. The amount of IAC and reductant (Tris(2-carboxyethyl)phosphine (TCEP)) was carefully optimized to avoid overalkylation. By a combination of capillary HPLC and HRMS, a method could be developed for the quality control of complex synthetic peptide pools. In contrast to the analysis of single peptides, analyzing complex peptide pools requires the stabilization of cysteine-containing peptides. Good results were obtained using iodoacetic acid as an alkylation reagent.

Evaluation of the Antioxidant Activities and Phenolic Profile of Shennongjia Apis cerana Honey through a Comparison with Apis mellifera Honey in China

This study evaluates the phenolic profile as well as the antioxidant properties of Shennongjia Apis cerana honey through a comparison with Apis mellifera honey in China. The total phenolic content (TPC) ranges from 263 ± 2 to 681 ± 36 mg gallic acid/kg. The total flavonoids content (TFC) ranges from 35.9 ± 0.4 to 102.2 ± 0.8 mg epicatechin/kg. The correlations between TPC or TFC and the antioxidant results (FRAP, DPPH, and ABTS) were found to be statistically significant (p < 0.01). Furthermore, the phenolic compounds are quantified and qualified by high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS), and a total of 83 phenolic compounds were tentatively identified in this study. A metabolomics analysis based on the 83 polyphenols was carried out and subjected to principal component analysis and orthogonal partial least squares-discriminant analysis. The results showed that it was possible to distinguish Apis cerana honey from Apis mellifera honey based on the phenolic profile.

HDPairFinder: A data processing platform for hydrogen/deuterium isotopic labeling-based nontargeted analysis of trace-level amino-containing chemicals in environmental water

The combination of hydrogen/deuterium (H/D) formaldehyde-based isotopic methyl labeling with solid-phase extraction and high-performance liquid chromatography–high resolution mass spectrometry (HPLC-HRMS) is a powerful analytical solution for nontargeted analysis of trace-level amino-containing chemicals in water samples. Given the huge amount of chemical information generated in HPLC-HRMS analysis, identifying all possible H/D-labeled amino chemicals presents a significant challenge in data processing. To address this, we designed a streamlined data processing pipeline that can automatically extract H/D-labeled amino chemicals from the raw HPLC-HRMS data with high accuracy and efficiency. First, we developed a cross-correlation algorithm to correct the retention time shift resulting from deuterium isotopic effects, which enables reliable pairing of H- and D-labeled peaks. Second, we implemented several bioinformatic solutions to remove false chemical features generated by in-source fragmentation, salt adduction, and natural 13C isotopes. Third, we used a data mining strategy to construct the AMINES library that consists of over 38,000 structure-disjointed primary and secondary amines to facilitate putative compound annotation. Finally, we integrated these modules into a freely available R program, HDPairFinder.R. The rationale of each module was justified and its performance tested using experimental H/D-labeled chemical standards and authentic water samples. We further demonstrated the application of HDPairFinder to effectively extract N-containing contaminants, thus enabling the monitoring of changes of primary and secondary N-compounds in authentic water samples. HDPairFinder is a reliable bioinformatic tool for rapid processing of H/D isotopic methyl labeling-based nontargeted analysis of water samples, and will facilitate a better understanding of N-containing chemical compounds in water.

Carbon-doped Co3O4-MgO catalyzed peroxymonosulfate activation via an enhanced Co(III)/Co(II) cycle for rapid chloramphenicol degradation

Advanced oxidation processes based on heterogeneous peroxymonosulfate activation (PMS) have been a feasible strategy for removing organic pollutants. In this study, the waste filter membranes in the laboratory were used as a carbon material, which combines with cobalt and magnesium to obtain the carbon-doped cobalt-magnesium binary oxides (C/Co3O4–MgO) after calcination to activate PMS for chloramphenicol (CAP) degradation. The results revealed that the degradation efficiency of CAP in the C/Co3O4–MgO/PMS system reached 98% within 15 min, much higher than those in C/Co3O4/PMS (62%) and Co3O4–MgO/PMS (68%) systems. The excellent catalytic performance of the C/Co3O4–MgO material was attributable to a good synergistic interaction between C, Co, and Mg. Electron paramagnetic resonance test and quenching experiments confirmed that •OH, SO4•−, and 1O2 were reactive oxygen species involved in CAP degradation. The intermediates of CAP degradation were analyzed via a high-performance liquid chromatography–high-resolution mass spectrometry method, and the possible degradation pathways of CAP were proposed. C/Co3O4–MgO exhibited good stability and reusability. The concentration of leached Co ions was lower than 0.53 mg L−1, and over 95% of CAP was still decomposed in the fifth cycle. Furthermore, the degradation of rhodamine B, sulfamethazine, and phenacetin via PMS activation by C/Co3O4–MgO was investigated. These three pollutants are almost completely degraded within 10 min. Therefore, C/Co3O4–MgO is an excellent heterogeneous catalyst used for activating PMS to degrade organic pollutants.

Biosynthesis of Chlorophyll and Other Isoprenoids in the Plastid of Red Grape Berry Skins.

Despite current knowledge showing that fruits like tomato and grape berries accumulate different components of the light reactions and Calvin cycle, the role of green tissues in fruits is not yet fully understood. In mature tomato fruits, chlorophylls are degraded and replaced by carotenoids through the conversion of chloroplasts in chromoplasts, while in red grape berries, chloroplasts persist at maturity and chlorophylls are masked by anthocyanins. To study isoprenoid and lipid metabolism in grape skin chloroplasts, metabolites of enriched organelle fractions were analyzed by high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS) and the expression of key genes was evaluated by real-time polymerase chain reaction (PCR) in berry skins and leaves. Overall, the results indicated that chloroplasts of the grape berry skins, as with leaf chloroplasts, share conserved mechanisms of synthesis (and degradation) of important components of the photosynthetic machinery. Some of these components, such as chlorophylls and their precursors, and catabolites, carotenoids, quinones, and lipids have important roles in grape and wine sensory characteristics.

Identification and Quantification of Dimethachlon Degradation Products in Soils and Their Effects on Soil Enzyme Activities.

In this study, high-performance liquid chromatography-high-resolution mass spectrometry (HPLC-HRMS, Q-Exactive Orbitrap) and Compound Discoverer 3.3 were used to screen dimethachlon degradation products in soils. Four metabolites 4-(3,5-dichloroanilino)-4-oxobutanoic acid (DCBAA), 3,5-dichloroaniline (3,5-DCA), succinic acid, and muconic acid were confirmed by primary and secondary ion mass spectrometry comparisons between standards and samples. A quantitative analysis method of dimethachlon residues and four metabolites in soils was developed using HPLC-HRMS. Dimethachlon degradation in agricultural soil indoor unsterilized, sterilized, and field environments in three typical areas was measured. Dimethachlon degraded fast with a half-life of less than 1 day in three nonsterile soils. The maximum DCBAA and 3,5-DCA residues during degradation could reach 22.5-35.2% of the initial concentration of the parent dimethachlon. The metabolite DCBAA had a greater impact on soil enzyme activity than the parent dimethachlon.

Determination of Nitrogen Mustard Metabolites in Urine Using High-Performance Liquid Chromatography–High-Resolution Mass Spectrometry

Determination of Nitrogen Mustard Metabolites in Urine Using High-Performance Liquid Chromatography–High-Resolution Mass Spectrometry

Characterization of the antagonistic potential of the glyphosate-tolerant Pseudomonas resinovorans SZMC 25872 strain against the plant pathogenic bacterium Agrobacterium tumefaciens.

The utilization of microorganisms with biocontrol activity against fungal and bacterial pathogens of plants is recognized as a promising, effective, and environment-friendly strategy to protect agricultural crops. We report the glyphosate-tolerant Pseudomonas resinovorans SZMC 25872 isolate as a novel strain with antagonistic potential towards the plant pathogenic bacterium Agrobacterium tumefaciens. In our studies, the growth of the P. resinovorans SZMC 25872 and A. tumefaciens SZMC 14557 isolates in the presence of 74 different carbon sources, and the effect of 11 carbon sources utilized by both strains on the biocontrol efficacy was examined. Seven variations of media with different carbon sources were selected for the assays to observe the biocontrol potential of the P. resinovorans strain. Also, 50% concentrations of the cell-free culture filtrates (CCF) obtained from medium amended with L-alanine or succinic acid as sole carbon source were found to be effective for the growth suppression of A. tumefaciens by 83.03 and 56.80%, respectively. The effect of 7 media on siderophore amount and the activity of extracellular trypsin- and chymotrypsin-like proteases, as well as esterases were also evaluated. Significant positive correlation was found between the siderophore amount and the percentage of inhibition, and the inhibitory effect of the CCFs obtained from medium amended with succinic acid was eliminated in the presence of an additional iron source, suggesting that siderophores produced by P. resinovorans play an important role in its antagonistic potential. The metabolic profile analysis of the P. resinovorans SZMC 25872 strain, performed by high performance liquid chromatography - high resolution mass spectrometry (HPLC-HRMS), has identified several previously not reported metabolites that might play role in the antagonistic effect against A. tumefaciens. Based on our findings we suggest that the possible inhibition modes of A. tumefaciens SZMC 14557 by P. resinovorans SZMC 25872 include siderophore-mediated suppression, extracellular enzyme activities and novel bioactive metabolites.

Characterization of Tequila by High Performance Liquid Chromatography – High Resolution Mass Spectrometry (HPLC-HRMS) and Partial Least Squares Regression (PLS)

The feasibility of raw data acquired by liquid chromatography – high resolution mass spectrometry for the separation of four tequila corresponding to different maturation stages was demonstrated using partial least squares regression (PLS). Five samples of silver, rested, aged, and extra-aged tequilas from different manufacturers were analyzed each in two technical replicates. Prior to the analysis, the samples were four-fold diluted with 0.1% trifluoroacetic acid. Rectangle bucketing was performed for raw data, with a retention time width of 60 s and m/z width of 1. The prepared dataset was submitted to principal component analysis (PCA) which allowed for the detection of tequila contaminants identified to be N-lauryl diethanolamine and phthalate esters. Next, PLS was performed on depurated data, annotating tequila categories as follows: 0 - silver, 1 - rested, 2 - aged and 3 - extra aged. In the computed model, two principal components accounted for 64% and 98% of X-data and Y-data variability, respectively. Cross-validation revealed similar analytical performance in calibration and in prediction with root mean square errors of 0.1851 and 0.2082, respectively. The assignation of category’s numerical value (0-3) was attained for eight randomly selected tequilas (two per category). Statistical differences between predicted values were obtained for each pair of categories except for the aged versus extra-aged liquors (ANOVA, p < 0.05). Overall, the assignation of tequila category was achieved with no need for the detection/identification nor quantification of individual compounds.

New Oligomeric Dihydrochalcones in the Moss Polytrichum commune: Identification, Isolation, and Antioxidant Activity.

One of the most widespread representatives of mosses in the temperate and boreal latitudes of the Northern Hemisphere is common haircap (Polytrichum commune), which is known as the largest moss in the world and widely used in traditional herbal medicine. Polyphenolic compounds constitute one of the most important groups of biologically active secondary metabolites of P. commune, however, the available information on their chemical composition is still incomplete and contradictory. In the present study, a group of dihydrochalcone polyphenolic derivatives that were not previously found in mosses was isolated from P. commune biomass using pressurized liquid extraction with aqueous acetone. The combination of two-dimensional NMR spectroscopy and high-performance liquid chromatography–high-resolution mass spectrometry allowed for identifying them as 3-hydroxyphloretin oligomers formed through a carbon–carbon bond between phloroglucinol and pyrocatechol moieties (“head-to-tail” coupling), with a polymerization degree of 2–5. The individual compounds isolated by preparative reverse-phase HPLC had a purity of 71 to 97% and demonstrated high radical scavenging activity (17.5–42.5% with respect to Trolox) determined by the photochemiluminescence method. Along with the low toxicity predicted by QSAR/QSTR algorithms, this makes 3-hydroxyphloretin oligomers a promising source for the production of biologically active food additives and pharmaceuticals.