Boric acids decorated polymers with Au nanoparticle anchor assisted laser desorption/ionization for qualitive and quantitative analysis of hydroxytyrosol in red wines

Hydroxytyrosol possesses a variety of biological and pharmacological activities that are beneficial to human health. However, the methodologies for its detection always suffered from problems. In this work, the gold nanoparticle modified polymer decorated with boric acids (pMBA/VPBA@Au) was synthesized and used both as the adsorbent and matrix to enrich and ionize small molecule substances through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The pMBA/VPBA@Au displayed a low detection limit (8 × 10-6 M) and high selectivity (1:100) for the enrichment of hydroxytyrosol, and the linear correlation curve between the concentration of hydroxytyrosol and the intensity of MS had a good correlation (10-4-10-2 M, R2 = 0.997). Additionally, the pMBA/VPBA@Au was used to quantify hydroxytyrosol in red wines, and the contents were 0.053-0.094 μg/mL. In general, a simple and novel method for the detection of hydroxytyrosol by SALDI-MS using boric acid functionalized polymer was developed for the first time, showing a good practical application value.

Effects of Silane Monolayers on Lysophosphatidylcholine (LysoPC) Detection by Desorption Ionization on Silicon Mass Spectrometry (DIOS-MS) in Solution and Plasma

Desorption ionization on silicon mass spectrometry (DIOS-MS) enables high throughput analysis of low-molecular-weight biomolecules. However, detection of metabolite biomarkers in complex fluids such as plasma requires sample pretreatment, limiting clinical application. Here, we show that porous silicon, chemically modified using monolayers of n-propyldimethylmethoxysilane molecules, is a good candidate for fingerprinting lysophosphatidylcholine (lysoPC) in plasma, without sample pretreatment, for DIOS-MS-based diagnosis (e.g., sepsis). Results were correlated to lysoPC molecule location inside/outside the pores, determined by time-of-flight secondary ion mass spectrometry profiling, and to physicochemical properties.

Ultrasensitive quantification of trace amines based on N-phosphorylation labeling chip 2D LC-QQQ/MS

Trace amines (TAs) are metabolically related to catecholamine and associated with cancer and neurological disorders. Comprehensive measurement of TAs is essential for understanding pathological processes and providing proper drug intervention. However, the trace amounts and chemical instability of TAs challenge quantification. Here, diisopropyl phosphite coupled with chip two-dimensional (2D) liquid chromatography tandem triple-quadrupole mass spectrometry (LC-QQQ/MS) was developed to simultaneously determine TAs and associated metabolites. The results showed that the sensitivities of TAs increased up to 5520 times compared with those using nonderivatized LC-QQQ/MS. This sensitive method was utilized to investigate their alterations in hepatoma cells after treatment with sorafenib. The significantly altered TAs and associated metabolites suggested that phenylalanine and tyrosine metabolic pathways were related to sorafenib treatment in Hep3B cells. This sensitive method has great potential to elucidate the mechanism and diagnose diseases considering that an increasing number of physiological functions of TAs have been discovered in recent decades.

Soy protein degradation drives diversity of amino-containing compounds via Bacillus subtilis natto fermentation

Food fermentation has been playing an important role in producing bioactive components (e.g., peptides), which exert many healthy effects. In this study, it was observed that natto possessed significantly higher angiotensin I-converting enzyme (ACE) inhibitory effect than soybean. Meanwhile, a total of 246 amino-containing compounds were identified via LC-Q-TOF-MS/MS, including amino acids, dipeptides, tripeptides, O-methyl-peptide, and biogenic amines, 187 of them were only detected in natto. Of the list, dipeptides, with ACE inhibitory abilities or potentials, were found to be the most significantly up-regulated class and positively correlated with significantly increased ACE inhibitory activity of natto. Moreover, dynamic profiling elucidated the increased dipeptides were generated from water soluble and insoluble protein via Bacillus subtilis natto fermentation. Taken together, this study enriches the chemical diversity of natto and provides an in-depth insight into the degradation mechanism of soy protein during natto fermentation, which can be extended to other functional foods.

Emerging environmental pollutants hydroxylated polybrominated diphenyl ethers: From analytical methods to toxicology research

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) are of particular concern due to their ubiquitous distribution and adverse health effects. Significant progress has been made in the characterization of OH-PBDEs by using mass spectrometry (MS). In this review, we summarize applications of MS-based techniques in detection, environmental and biota distribution, and potential health risk effects, hoping to unfold an overall picture on account of current knowledge of OH-PBDEs. The analytical methodologies are discussed from sample pretreatment to MS analysis. The methods including gas chromatography-MS (GC-MS), liquid chromatography-MS (LC-MS), and ion mobility spectrometry-MS (IMS-MS) are discussed. GC-MS is the most frequently adopted method in the analysis of OH-PBDEs due to its excellent chromatographic resolution, high sensitivity, and strong ability for unknown identification. LC-MS has been widely used for its high sensitivity and capability of direct analysis. As a newly developed technique, IMS-MS provides high specificity, which greatly facilitates the identification of isomers. OH-PBDEs pervasively existed in both abiotic and biotic samples, including humans, animals, and environmental matrices. Multiple adverse health effects have been reported, such as thyroid hormone disruption, estrogen effects, and neurotoxicity. The reported potential pathological mechanisms are also reviewed. Additionally, MS-based metabolomics, lipidomics, and proteomics have been shown as promising tools to unveil the molecular mechanisms of the toxicity of OH-PBDEs. © 2020 John Wiley & Sons Ltd. Mass Spec Rev.

Options of the Main Derivatization Approaches for Analytical ESI and MALDI Mass Spectrometry

The inclusion of preliminary chemical labeling (derivatization) in the analysis process by such powerful and widespread methods as electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is a popular and widely used methodological approach. This is due to the need to remove some fundamental limitations inherent in these powerful analytic methods. Although a number of special reviews has been published discussing the utilization of derivatization approaches, the purpose of the present critical review is to comprehensively summarize, characterize and evaluate most of the previously developed and practically applied, as well as recently proposed representative derivatization reagents for ESI-MS and MALDI-MS platforms in their mostly sensitive positive ion mode and frequently hyphenated with separation techniques. The review is focused on the use of preliminary chemical labeling to facilitate the detection, identification, structure elucidation, quantification, profiling or MS imaging of compounds within complex matrices. Two main derivatization approaches, namely the introduction of permanent charge-fixed or highly proton affinitive residues into analytes are critically evaluated. In situ charge-generation, charge-switch and charge-transfer derivatizations are considered separately. The potential of using reactive matrices in MALDI-MS and chemical labeling in MS-based omics sciences is given.

Stand out from matrix: Ultra-sensitive LC-MS/MS method for determination of histamine in complex biological samples using derivatization and solid phase extraction

The determination of low abundant endogenous components is a challenge for the clinical samples. Histamine, a crucial endogenous component, fulfils various regulatory and mediatory functions in human, and the change of content is a critical index for the diagnosis of some diseases, especially allergy, asthma, and anaphylactic shock. However, it is challenging to detect histamine because of the low stability and concentration in complex biological samples. Here we developed an ultra-sensitive and accurate LC-MS/MS quantification method based on derivatization, isotope dilution, and solid phase extraction. The derivatization of histamine with diisopropyl phosphite (DIPP) not only enhanced the retention on the LC column but also improved the ionization efficiency. Next, solid phase extraction was applied to remove the interference, which finally resulted in standing out of the trace histamine from the high contents of the matrix. The lowest limit of quantification (LLOQ) was 0.1 pg/mL that is enough low to determine the histamine in one cell and low nano-liter of serum. This approach was successfully applied for the quantification of histamine in clinical serum samples of asthma patients and mast cell treated with chemicals modulating histamine release.

Opening up the Toolbox: Synthesis and Mechanisms of Phosphoramidates

This review covers the main synthetic routes to and the corresponding mechanisms of phosphoramidate formation. The synthetic routes can be separated into six categories: salt elimination, oxidative cross-coupling, azide, reduction, hydrophosphinylation, and phosphoramidate-aldehyde-dienophile (PAD). Examples of some important compounds synthesized through these routes are provided. As an important class of organophosphorus compounds, the applications of phosphoramidate compounds, are also briefly introduced.

Sinomenine-induced histamine release-like anaphylactoid reactions are blocked by tranilast via inhibiting NF-κB signaling

Zhengqing Fengtongning (ZQFTN), the pharmaceutical preparation of sinomenine (SIN) derived from the medicinal plant Sinmenium acutum, is well-known in China as an effective treatment for rheumatoid arthritis (RA). However, its histamine-release anaphylactoid reactions (HRARs) occur often in some patients. Therefore, it is desirable to establish effective clinical protocols to manage such HRARs. In the study, rat models with systemic HRARs and local HRARs of the skin were established. The level of vascular permeability and mast cell numbers was determined by quantitative analysis using Evans blue dye and histological assays. The levels of histamine, leukotriene B4 (LTB4) and IL-33 in plasma were detected by UHPLC-SPE-MS, ELISA and immunohistochemistry assays, respectively. The results demonstrated that SIN significantly induced both systemic and local HRARs in rats, showing significant decrease of body temperature, increases in vascular permeability in skin, injury of lung tissues and mast cell infiltration and IL-33 expression in skin and lung tissues. Mechanistic study showed that tranilast could prevent SIN-triggered HRARs via inhibition of H1 receptor gene expression and NF-κB signaling. Our findings provide evidence that mast cell membrane stabilizers and H1 receptor blockers effectively prevent SIN-induced HRARs, and cromolyn, cetirizine and tranilast can be used in the clinic for the management of HRARs induced by ZQFTN.

Imidazolium-based iodoacetamide functional tags: design, synthesis, and property study for cysteinyl-peptide analysis by mass spectrometry

New types of imidazolium-based iodoacetamide tags were designed, synthesized and further exploited for cysteinyl-peptide analysis with superior labeling efficiency, high stability, improved ionization efficiency, and increased charge states by mass spectrometry. For the first time, the effects of these kinds of tags on the mass spectrometry performance of the derivatized peptides were investigated, which is of great importance to help us design more efficient tags for the analysis of peptides or proteins, especially for those with low abundance.

A novel quantification method for analysis of twenty natural amino acids in human serum based on N-phosphorylation labeling using reversed-phase liquid chromatography-tandem mass spectrometry

A novel method based on the strategy of N-phosphorylation labeling is described for quantification of twenty natural amino acids in human serum by reversed-phase liquid chromatography-electrospray tandem mass spectrometry (RP-LC/ESI-MS). The derivatization reaction was easily performed in one-pot reaction under mild conditions within 30min. The reaction mixture was then evaporated to dryness, redissolved, desalted by C18 SPE. The twenty N-phosphoryl amino acids were separated on an RP-C18 column within 20min by isocratic elution (0.1% formic acid-acetonitrile, v/v 7:3). At the same time, multiple reaction monitoring (MRM) MS enabled quantitation of twenty natural amino with the LOD of 0.0005-0.15μM and LOQ of 0.0020-0.5μM in human serum. The linear range was from 0.025 to 25μM (except Cys and Trp) with R>0.99. The recovery range was determined to be 85.5-117.4% with the relative standard deviation (RSD) in the range of 1.3-13.9%. All twenty amino acids were successfully detected in human serum samples with the concentration from 5.7 to 577.9μM, which indicates potential of the developed method for determination of amino acids in complex biological samples, hence for screening of amino acid metabolite related diseases.