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Chinese onion is a common vegetable in daily diet, especially in Southwest China. We collected 184 samples from farm and market in Chongqing Municipality during 2020–2021 and established a multi-residue method for analysis of 79 pesticide residues on Chinese onion. Sixty-three of 184 samples were found pesticide resdues, accounting for 34.2%. A total of 31 pesticides were detected, and 6 pesticides in 11 samples have exceeded the Chinese MRLs, 5.98% of all samples. The chronic and acute dietary exposure assessment showed the %ADI and the %ARfD value were 0.005%–5.46% and 0.03%–297.95%, respectively. The %ARfD of most pesticides were acceptable except for cyhalothrin (297.95%, children; 140.17%, adults) and carbofuran (107.94%, children). The study indicated that pesticide residues on Chinese onion had different concentration levels which were low commonly. The establishment of MRLs for several pesticides (cyfluthrin, carbendazim, propamocarb) in Chinese onion is required for better estimation of dietary risk. [ABSTRACT FROM AUTHOR]

Date Palm (Phoenix dactylifera) is one of the important fruit enriched with an impressive list of essential nutrients and a wide range of phenolic compounds with high antibacterial compounds. In order to provide further detailed information on phenolic compounds and antibacterial activities of Date Palm (Phoenix dactylifera), the current study was devoted to investigate and compare three different highly consumable varieties of date palm (Phoenix dactylifera) cultivars, namely Ajwa, Khalas Alkharj, and Al-Qasim for their broad spectrum antibacterial effect and phenolic compounds. The antibacterial properties of their methanolic extracts were evaluated against Streptococcus pnuemoniae, Bacillus subtilis, Klebsiella pneumonia, Staphylococcus aureus, Escherichia coli. All of the three cultivars displayed a broad spectrum of inhibitory effect against these pathogenic bacteria. Moverover, the LC-Linear Ion Quadrupole Mass Spectrometric Analysis (LC-MS and LC-MS/MS Tandem Mass Spectrometry) analysis revealed the presence of 3,30-di-O-methyl ellagic acid, 7-Methoxyquercetin-O-hexose isomers, caffeic acid, ferulic acid, isomers of quercentin-rutinoside, kaempferol methylether, p hydroxybenzoic acid, phytol, punicalagin and quercetin-3-O-glucoside (isoquercitrin) were in Ajwa, 3,30-di-O-methyl ellagic acid isomers, 3,30-di-O-methyl ellagic acid, caffeic acid derivative, cafeic acid, caffeoyl glucose, caffeoylshikimic acid, ferulic acid, guaiacyl(8-5)ferulic acid hexoside isomer, isorhamnetin-3-Ohexoside, oxooctadecanoic acid, punicalagin and quercetin derivativein Al-Qasim extracts while 2(3,4-Dihydroxyphenyl)-7-hydroxy-5-benzene propanoic acid isomer, 2 (3,4-Dihydroxyphenyl)-7-hydroxy-5-benzene propanoic acid, decanoic acid derivative, diosmetin, kaempferol-3-rutinoside, linolenic acid, oxooctadecanoic acid conjugate and punicalagin in the extract of Khalas date. The findings of the current study may increase our knowledge about the importance of dates in diet and can be utilized as natural antimicrobial agents in the foods industry. [ABSTRACT FROM AUTHOR]

Tacrolimus has been widely applied to prevent organ rejection after transplantation. However, the conventional pharmaceutical formulation of tacrolimus limits its applications in ocular therapy due to its hydrophobicity and low corneal penetrability. We optimized tacrolimus-loaded methoxy poly (ethylene glycol-block-poly (d, l)-lactic-co-glycolic acid) nanoparticles (TAC-NPs) by simple and effective nanotechnology as a drug delivery system for corneal graft rejection to overcome these drawbacks. The prepared TAC-NPs were 82.9 ± 1.3 nm in size, and the drug loading and encapsulation efficiency were 8.01 ± 0.23% and 80.10 ± 2.33%. Furthermore, New Zealand rabbits were used to analyze the single-dose pharmacokinetics of the TAC-NPs using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). In rats with allogenic penetrating keratoplasty, the administration of TAC-NPs dispersion drops improved the TAC concentrations in the aqueous humor and cornea, consistent with a significantly higher effective inhibition of IL-2, IL-17, and VEGF expression compared with conventional 0.1% tacrolimus drops. Meanwhile, we also compared two different topical administration methods (including eye drop and subconjunctival injection) of TAC-NPs to maximize the sustained release characteristic of NPs. In summary, the small-sized TAC-NPs enhanced transcorneal permeation and absorption of TAC and more effectively inhibited corneal allograft rejection, which indicated that biodegradable polymeric nanomaterials-based drug delivery system had great potential for improving the clinical therapy efficacy of hydrophobic drugs. [ABSTRACT FROM AUTHOR]

Context: 1 D is a novel derivative of curcumin and shows very promising antitumor activities in various cancer cell lines. Objective: To characterize its preclinical pharmacokinetic profiles, a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of 1 D in rat plasma. Materials and methods: An aliquot of 50 μL plasma sample was processed by protein precipitation with methanol. Chromatographic separation was accomplished on a Zorbax Eclipse Plus C18 column (2.1 mm × 50 mm, 1.8 μm) with a gradient elution system (water/0.1% formic acid and methanol). Detection was performed by multiple reaction monitoring (MRM) mode using electrospray ionization in the positive ion mode. The optimized fragmentation transition for 1 D was m/z 491.2 → 361.2. Results: The method was linear over the concentration range of 5–1000 ng/mL. The intra- and inter-day precisions were less than 9.8% and the accuracy was within ± 14.5%. The mean recovery of 1 D ranged from 102.5 to 105.9%. No matrix effects and significant sample loss during sample processing were observed. The validated method has been successfully applied to a pharmacokinetic study in rats after intravenous administration of 1 D. Non-compartmental pharmacokinetic parameters, including half-life (t1/2), apparent volume of distribution (Vz), clearance (CLz), and area under the concentration-time curve (AUC(0–t)) were 4.92 h, 46.56 L/kg, 6.33 L/h/kg, and 806.70 μg/L/h, respectively. Discussion and conclusions: Results demonstrated that 1 D displayed favourable pharmacokinetic properties for further in vivo pharmacologic evaluation, which could be facilitated by the validated LC-MS/MS method. [ABSTRACT FROM AUTHOR]

Long-term weight loss maintenance is a problem of overweight and obesity. Changes of gene expression during weight loss (WL) by calorie restriction (CR) are linked to the risk of weight regain (WR). However, detailed information on genes/proteins involved in the mechanism is still lacking. Therefore, we developed an in-vitro model system for glucose restriction (GR) and refeeding (RF) to uncover proteome differences between GR with RF vs normal feeding, of which we explored the relation with WR after WL. Human Simpson-Golabi-Behmel Syndrome cells were subjected to changing levels of glucose to mimic the condition of CR and RF. Proteome profiling was performed by liquid chromatography tandem mass spectrometry. This in-vitro model revealed 44 proteins differentially expressed after GR and RF versus feeding including proteins of the focal adhesions. Four proteins showed a persistent up- or down-regulation: liver carboxylesterase (CES1), mitochondrial superoxide dismutase [Mn] (SOD2), alpha-crystallin B-chain (CRYAB), alpha-enolase (ENO1). In-vivo weight loss-induced RNA expression changes linked CES1, CRYAB and ENO1 to WR. Moreover, of these 44 proteins, CES1 and glucosidase II alpha subunit (GANAB) during follow up correlated with WR. Correlation clustering of in-vivo protein expression data indicated an interaction of these proteins with structural components of the focal adhesions and cytoplasmic filaments in the adipocytes. [ABSTRACT FROM AUTHOR]

Objective: Iron overload and oxidative stress are the major causes of serious complications and mortality in thalassemic patients. Our previous work supports the synergistic effects of antioxidant cocktails (curcuminoids or vitamin E, N-acetylcysteine, and deferiprone) in treatment of β-thalassemia/Hb E patients. This further 2-DE-based proteomic study aimed to identify the plasma proteins that expressed differentially in response to antioxidant cocktails. Methods: Frozen plasma samples of ten normal subjects and ten β-thalassemia/Hb E patients at three-time points (baseline, month 6, and month 12) were reduced the dynamic range of proteome using ProteoMiner kit and separated proteins by two-dimensional gel electrophoresis. Differentially expressed proteins were identified using tandem mass spectrometry. Several plasma proteins were validated by ELISA and Western blot analysis. Results: Thirteen and 11 proteins were identified with altered expression levels in the curcuminoids- and vitamin E cocktail groups, respectively. The associations between vitronectin (VTN) expression and total bilirubin levels, as well as between serum paraoxonase/arylesterase 1 (PON1) expression and blood reactive oxygen species were observed. Validation results were consistent with proteomics results. Discussion and conclusions: These plasma proteins may provide better understanding of the mechanisms underlying the therapeutic effects of antioxidant cocktails in thalassemic patients. [ABSTRACT FROM AUTHOR]

1G, a novel derivative of curcumin, exhibits promising anticancer activities in various cancer cell lines. To support its further pharmacological studies, a liquid chromatography–tandem mass spectrometry method was developed and validated in accordance with FDA's Guidance. After extraction by protein precipitation, analytes were separated by a 4.5 min gradient elution (water/0.1% formic acid and methanol) on a reverse-phase C18 column at 40 °C. The multiple reaction monitoring mode was used for quantification on a triple quadrupole mass spectrometer with positive ionization. The assay was linear over the concentration range of 5–1000 ng/mL with a correlation coefficient (r) greater than 0.99. Values of intra- and inter-day precision and accuracy were satisfactory, i.e. <10.1% for precision and within ± 14.5% for accuracy. No obvious matrix effect was observed. Recovery of the analyte was higher than 95.3%. 1G was stable during the whole analytic process. The validated method was successfully applied to the pharmacokinetic study of 1G after intravenous and intraperitoneal administration in rats. Favorable pharmacokinetic profiles were demonstrated, including good abdominal absorption (F = 62.58%), moderate clearance and high extravascular distribution. Results indicated that as a novel antitumor agent, 1G exhibited acceptable pharmacokinetic properties for further in vivo pharmacologic evaluation. [ABSTRACT FROM AUTHOR]

Familial adenomatous polyposis (FAP) is an autosomal dominantly inherited intestinal polyposis syndrome accounting for about 1% of colorectal cancers (CRC). Despite increasing researches on the molecular pathogenesis of CRC, we are still unclear about metabolic pathways and alterations probably involved in the development of CRC. To obtain new insights into the mechanisms underlying APC mutation and to elucidate the mechanisms of CRC development, we performed to identify the potential metabolites in FAP based on metabolomic strategy. Serum metabolites from FAP patients (n = 30) and healthy individuals (n = 34) were detected and qualified using Ultra Performance Liquid Chromatography and Tandem Mass Spectrometry (UPLC− MS/MS). 118 metabolites were identified with statistical tests of orthogonal partial least-squares-discriminant analysis (OPLS−DA), with the conditions of variable importance in projection (VIP) >1, p < 0.05 using the Mann−Whitney U test, and fold change (FC) ≥2 or ≤0.5. OPLS-DA model was useful for distinguishing FAP patients from healthy controls. Unique metabolic signatures were pooled in FAP patients covering tricarboxylic acid (TCA) cycle, amino acids metabolism, vitamin D, fatty acids metabolism, and bile acids (BAs) metabolism. Our results demonstrated that metabolites alterations in FAP can be helpful for further analysis of metabonomics induced by APC mutation, and these alterations might be involved in the progress of intestinal carcinogenesis. [ABSTRACT FROM AUTHOR]

Two hundred and seventy six mulberry juice samples were analyzed by high-performance liquid chromatography with diode-array detection quadrupole time-of-flight tandem mass spectrometry to identify the major polyphenols in the representative mulberry fruit cultivar Da10. Using FRAP, ABTS, and DPPH assays, total phenolic contents and antioxidant capacities of 276 mulberry juice samples from four provinces in China were found to be within the following ranges: 412.55–1471.86 mg/L gallic acid equivalent, 37.90–361.75 mmol/mL ferrous sulfate equivalent, 46.12–342.13 mmol/mL Trolox equivalent, and 7.30–216.41 mmol/mL ascorbic acid equivalent. Cluster analysis separated the cultivars into two groups. One group consisted of samples from Guangdong, Guangxi, and Hainan Provinces, which had high phenolic contents and antioxidant capacities. The other group consisted of samples from Xinjiang Province, which had low phenolic contents and antioxidant capacities. Antioxidant activity and phenolic content were correlated. Flavonoids were the main polyphenols of "Da10". In addition to free phenolic compounds, various bound phenolic compounds were identified. This work provides a large dataset characterizing different mulberry cultivars for deeper research. "45–7", "qianshan3" and "guoxuan04-129" were superior cultivars based on their high phenolic contents and antioxidant capacities. The results of this study support further research into mulberry use in human food and healthcare industries. [ABSTRACT FROM AUTHOR]

Herein, a QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure together with liquid chromatography and tandem mass spectrometry was applied to the multi-residue analysis of 203 pesticides in strawberries. To reduce the amount of co-eluents, we compared several dispersive solid-phase extraction cleanup procedures and found that cleanup using octadecylsilane provided the best recoveries. Spiked-sample recoveries of 70–120% with relative standard deviations of <20% were obtained for all tested pesticides except for quinmerac. Matrix-matched calibration curves exhibited good linearities (R2 > 0.99), and the limits of quantification (LOQs) were lower than the maximum residue limits recommended by the European Commission and Korea Food and Drug Administration. The developed method was applied to real samples, revealing that their pesticide contents exceeded the corresponding LOQs. The obtained results demonstrate that octadecylsilane-based dispersive solid-phase extraction is a rapid and high-throughput cleanup procedure for the multi-residue analysis of pesticides in strawberries. [ABSTRACT FROM AUTHOR]

We consider the problem of controlling the false discovery rate (FDR) among discoveries from searching an incomplete database. This problem differs from the classical multiple testing setting because there are two different types of false discoveries: those arising from objects that have no match in the database and those that are incorrectly matched. We show that commonly used FDR controlling procedures are inadequate for this setup, a special case of which is tandem mass spectrum identification. We then derive a novel FDR controlling approach which extensive simulations suggest is unbiased. We also compare its performance with problem-specific as well as general FDR controlling procedures using both simulated and real mass spectrometry data. [ABSTRACT FROM AUTHOR]

Protein arginine methyltransferase 1 (PRMT-1) catalyzes asymmetric arginine dimethylation on cellular proteins and modulates various aspects of biological processes, such as signal transduction, DNA repair, and transcriptional regulation. We have previously reported that the null mutant of prmt-1 in Caenorhabditis elegans exhibits a slightly shortened life span, but the physiological significance of PRMT-1 remains largely unclear. Here we explored the role of PRMT-1 in mitochondrial function as hinted by a two-dimensional Western blot-based proteomic study. Subcellular fractionation followed by liquid chromatography-tandem mass spectrometry (LCMS/MS) analysis showed that PRMT-1 is almost entirely responsible for asymmetric arginine dimethylation on mitochondrial proteins. Importantly, isolated mitochondria from prmt-1 mutants represent compromised ATP synthesis in vitro, and wholeworm respiration in prmt-1 mutants is decreased in vivo. Transgenic rescue experiments demonstrate that PRMT-1-dependent asymmetric arginine dimethylation is required to prevent mitochondrial reactive oxygen species (ROS) production, which consequently causes the activation of the mitochondrial unfolded-protein response. Furthermore, the loss of enzymatic activity of prmt-1 induces food avoidance behavior due to mitochondrial dysfunction, but treatment with the antioxidant N-acetylcysteine significantly ameliorates this phenotype. These findings add a new layer of complexity to the posttranslational regulation of mitochondrial function and provide clues for understanding the physiological roles of PRMT-1 in multicellular organisms. [ABSTRACT FROM AUTHOR]

To identify the metabolite distribution in ascidian, we have applied an integrated liquid chromatography– tandem mass spectrometry (LC–MS) metabolomics approach to explore and identify patterns in chemical diversity of invasive ascidianStyela plicata. A total of 71 metabolites were reported among these alkaloids, fatty acids and lipids are the most dominant chemical group. Multivariate statistical analysis, principal component analysis (PCA) showed a clear separation according to chemical diversity and taxonomic groups. PCA and partial least square discriminant analysis were applied to discriminate the chemical group ofS. plicatacrude compounds and classify the compounds with unknown biological activities. In this study, we reported for the first time that a partially purified methanol extract prepared from the ascidianS. plicataandAscidia mentulapossess antitumor activity against four tumor cell lines with different tumor histotype, such as HeLa (cervical carcinoma), HT29 (colon carcinoma), MCF-7 (breast carcinoma) and M14 (melanoma).S. plicatafraction SP-50 showed strong inhibition of cell proliferation and induced apoptosis in HeLa and HT29 cells, thus indicatingS. plicatafraction SP-50 a potential lead compound for anticancer therapy. The molecular mechanism of action and chemotherapeutic potential of these ascidian unknown biomolecules need further research. [ABSTRACT FROM PUBLISHER]

A rapid and selective liquid chromatography-mass spectrometry (LC-MS) method was developed for the evaluation of amlodipine and atorvastatin in human plasma. Detection of analytes was assigned by tandem mass spectrometry with electrospray ionization interface in positive ion mode was applied under the multiple-reaction monitoring mode (MRM). Analytes were extracted from plasma by simple liquid-liquid extraction technique using ethyl acetate. The reconstituted samples were chromatographed on C18 column by pumping acetonitrile-water (10 mM CH3COONH4, pH 3.0) = 70:30 (v/v) at a flow rate of 0.15 mL/min. The standard curves were assigned to be linear in the range of 0.2-20 ng/mL for atorvastatin and 0.1-10 ng/mL for amlodipine with mean correlation coefficient of ≥0.999 for each analyte. The intra-day and inter-day precision and accuracy results were well within the acceptable limits. The urbanized evaluate method was successfully applied to validation of amlodipine and atorvastatin in human plasma. [ABSTRACT FROM AUTHOR]

The cell wall integrity (CWI) checkpoint in the budding yeast Saccharomyces cerevisiae coordinates cell wall construction and cell cycle progression. In this study, we showed that the regulation of Hcm1, a late-S-phase transcription factor, arrests the cell cycle via the cell wall integrity checkpoint. Although the HCM1 mRNA level remained unaffected when the cell wall integrity checkpoint was induced, the protein level decreased. The overproduction of Hcm1 resulted in the failure of the cell wall integrity checkpoint. We identified 39 Hcm1 phosphorylation sites, including 26 novel sites, by tandem mass spectrometry analysis. A mutational analysis revealed that phosphorylation of Hcm1 at S61, S65, and S66 is required for the proper onset of the cell wall integrity checkpoint by regulating the timely decrease in its protein level. Hyperactivation of the CWI mitogen-activated protein kinase (MAPK) signaling pathway significantly reduced the Hcm1 protein level, and the deletion of CWI MAPK Slt2 resulted in a failure to decrease Hcm1 protein levels in response to stress, suggesting that phosphorylation is regulated by CWI MAPK. In conclusion, we suggest that Hcm1 is regulated negatively by the cell wall integrity checkpoint through timely phosphorylation and degradation under stress to properly control budding yeast proliferation. [ABSTRACT FROM AUTHOR]

Numerous oxidative modifications to proteins and amino acids have been identified with most susceptible, to varying degrees, of some form of oxidative modification. The consequence of oxidation on protein structure and function reveals that some of these modifications are functionally important. The discovery and accurate characterization/description of existing and new modifications requires modern instrumentation, great care, and attention to detail, especially if the modifications are present in low stoichiometric quantities or they only exist transiently. The focus of this brief review is on the use of mass spectrometry, protein chemistry, and proteomics methods and tools to identify oxidatively modified proteins and peptides along with the characterization of specific sites. Many of the specialized mass spectrometry technologies and techniques are becoming more widely available in research laboratories with mass spectrometry or proteomics facilities allowing even non-expert researchers in the field to accurately determine modifications. Illustrative examples of some approaches are provided from the author's work, collaborative research projects, and elsewhere. [ABSTRACT FROM AUTHOR]