Searching for Potential Lipid Biomarkers of Parkinson's Disease in Parkin-Mutant Human Skin Fibroblasts by HILIC-ESI-MS/MS: Preliminary Findings

Early diagnosis of neural changes causing cerebral impairment is critical for proposing preventive therapies for Parkinson’s disease (PD). Biomarkers currently available cannot be informative of PD onset since they are characterized by analysing post-mortem tissues from patients with severe degeneration of the substantia nigra. Skin fibroblasts (SF) are now recognized as a useful model of primary human cells, capable of reflecting the chronological and biological aging of the subjects. Here a lipidomic study of easily accessible primary SF is presented, based on hydrophilic interaction liquid chromatography coupled to electrospray ionization and mass spectrometry (HILIC/ESI-MS). Phospholipids (PL) from dermal fibroblasts of five PD patients with different parkin mutations and healthy control SF were characterized by single and tandem MS measurements using a hybrid quadrupole-Orbitrap and a linear ion trap mass analysers. The proposed approach enabled the identification of more than 360 PL. Univariate statistical analyses highlight abnormality of PL metabolism in the PD group, suggesting down- or up-regulation of certain species according to the extent of disease progression. These findings, although preliminary, suggest that the phospholipidome of human SF represents a source of potential biomarkers for the early diagnosis of PD. The dysregulation of ethanolamine plasmalogens in the circulatory system, especially those containing polyunsaturated fatty acids (PUFA), might be likely associated with neurodegeneration.

Comparative serum bactericidal activity of meropenem-based combination regimens against extended-spectrum beta-lactamase and KPC-producing Klebsiella pneumoniae

Combination therapies are frequently used in the treatment of multidrug-resistant Klebsiella pneumoniae infection without consensus regarding which combination is the most effective. We compared bactericidal titres from sera collected from critically ill patients receiving meropenem plus tigecycline (n = 5), meropenem plus colistin (n = 5), or meropenem, colistin and tigecycline (n = 5) against K. pneumoniae isolates that included ESBL-producing (n = 7) and KPC-producing strains (n = 14) with varying sensitivity patterns to colistin and tigecycline. Meropenem concentrations (C_min) were measured in all samples by LC-MS/MS, and indexed to respective pathogen MICs to explore differences in patterns of bactericidal activity for two versus three drug combination regimens. All combination regimens achieved higher SBTs against ESBL (median reciprocal titre 128, IQR 32-256) versus KPC (4, IQR 2-32) strains. Sera from patients treated with meropenem-colistin yielded higher median SBTs (256, IQR 64-512) than either meropenem-tigecycline (32, IQR 8-256; P < 0.001). The addition of tigecycline was associated with a lower probability of achieving a reciprocal SBT above 8 when meropenem concentrations were below the MIC (P = 0.04). Although the clinical significance is unknown, sera from patients receiving tigecycline-based combination regimens produce lower serum bactericidal titres against ESBL or KPC-producing K. pneumoniae. SBTs may represent a useful complimentary endpoint for comparing pharmacodynamics of combinations regimens for MDR Enterobacteriaceae.

Modulation of Milk Allergenicity by Baking Milk in Foods: A Proteomic Investigation

Cow's milk is considered the best wholesome supplement for children since it is highly enriched with micro and macro nutrients. Although the protein fraction is composed of more than 25 proteins, only a few of them are capable of triggering allergic reactions in sensitive consumers. The balance in protein composition plays an important role in the sensitization capacity of cow's milk, and its modification can increase the immunological response in allergic patients. In particular, the heating treatments in the presence of a food matrix have demonstrated a decrease in the milk allergenicity and this has also proved to play a pivotal role in developing tolerance towards milk. In this paper we investigated the effect of thermal treatment like baking of cow's milk proteins that were employed as ingredients in the preparation of muffins. A proteomic workflow was applied to the analysis of the protein bands highlighted along the SDS gel followed by western blot analyses with sera of milk allergic children in order to have deeper information on the impact of the heating on the epitopes and consequent IgE recognition. Our results show that incorporating milk in muffins might promote the formation of complex milk-food components and induce a modulation of the immunoreactivity towards milk allergens compared to milk baked in the oven at 180 °C for ten minutes. The interactions between milk proteins and food components during heating proved to play a role in the potential reduction of allergenicity as assessed by in vitro tests. This would help, in perspective, in designing strategies for improving milk tolerance in young patients affected from severe milk allergies.

LC-MS/MS Analysis of the Emerging Toxin Pinnatoxin-G and High Levels of Esterified OA Group Toxins in Galician Commercial Mussels

The occurrence of marine harmful algae is increasing worldwide and, therefore, the accumulation of lipophilic marine toxins from harmful phytoplankton represents a food safety threat in the shellfish industry. Galicia, which is a commercially important EU producer of edible bivalve mollusk have been subjected to recurring cases of mussel farm closures, in the last decades. This work aimed to study the toxic profile of commercial mussels (Mytilus galloprovincialis) in order to establish a potential risk when ingested. For this, a total of 41 samples of mussels farmed in 3 Rías (Ares-Sada, Arousa, and Pontevedra) and purchased in 5 local markets were analyzed by liquid chromatography tandem mass spectrometry (LC–MS/MS). Chromatograms showed the presence of okadaic acid (OA), dinophysistoxin-2 (DTX-2), pectenotoxin-2 (PTX-2), azaspiracid-2 (AZA-2), and the emerging toxins 13-desmethyl spirolide C (SPX-13), and pinnatoxin-G (PnTX-G). Quantification of each toxin was determined using their own standard calibration in the range 0.1%–50 ng/mL (R2 > 0.99) and by considering the toxin recovery (62–110%) and the matrix correction (33–211%). Data showed that OA and DTX-2 (especially in the form of esters) are the main risk in Galician mollusks, which was detected in 38 samples (93%) and 3 of them exceeded the legal limit (160 µg/kg), followed by SPX-13 that was detected in 19 samples (46%) in quantities of up to 28.9 µg/kg. Analysis from PTX-2, AZA-2, and PnTX-G showed smaller amounts. Fifteen samples (37%) were positive for PTX-2 (0.7–2.9 µg/kg), 12 samples (29%) for AZA-2 (0.1–1.8 µg/kg), and PnTX-G was detected in 5 mussel samples (12%) (0.4 µg/kg–0.9 µg/kg). This is the first time Galician mollusk was contaminated with PnTX-G. Despite results indicating that this toxin was not a potential risk through the mussel ingestion, it should be considered in the shellfish safety monitoring programs through the LC–MS/MS methods.

A Comprehensive Analysis of Ontogeny of Renal Drug Transporters: mRNA Analyses, Quantitative Proteomics, and Localization

Human renal membrane transporters play key roles in the disposition of renally cleared drugs and endogenous substrates, but their ontogeny is largely unknown. Using 184 human postmortem frozen renal cortical tissues (preterm newborns to adults) and a subset of 62 tissue samples, we measured the mRNA levels of 11 renal transporters and the transcription factor pregnane X receptor (PXR) with quantitative real‐time polymerase chain reaction, and protein abundance of nine transporters using liquid chromatography tandem mass spectrometry selective reaction monitoring, respectively. Expression levels of p‐glycoprotein, urate transporter 1, organic anion transporter 1, organic anion transporter 3, and organic cation transporter 2 increased with age. Protein levels of multidrug and toxin extrusion transporter 2‐K and breast cancer resistance protein showed no difference from newborns to adults, despite age‐related changes in mRNA expression. Multidrug and toxin extrusion transporter 1, glucose transporter 2, multidrug resistance‐associated protein 2, multidrug resistance‐associated protein 4 (MRP4), and PXR expression levels were stable. Using immunohistochemistry, we found that MRP4 localization in pediatric samples was similar to that in adult samples. Collectively, our study revealed that renal drug transporters exhibited different rates and patterns of maturation, suggesting that renal handling of substrates may change with age.

Identification of Products from Thermal Degradation of Tryptophan Containing Pentapeptides: Oxidation and Decarboxylation

In this contribution, we investigate the thermal decomposition of four pentapeptides containing a tryptophan moiety. Pentapeptides were heated at 220 °C, and the resulting reaction mixtures were investigated by HPLC coupled to high-resolution mass spectrometry and tandem mass spectrometry. A total of 95 thermal decomposition products could be observed and resolved by chromatography. In detail, we report on the structure assignment of two types of reaction products common to investigated peptides and introduce two decomposition mechanisms. Pentapeptides react with oxygen to produce hydroxyl-tryptophan derivatives. In addition, we observe the C-terminal decarboxylation of two peptides to form N-acyl tryptamine derivatives.

Comprehensive Assessment of Short-Lived ROS and H2O2 in Laser Printer Emissions: Assessing the Relative Contribution of Metal Oxides and Organic Constituents

Inhalation exposure to nanoparticles from toner-based laser printer and photocopier emissions (LPEs) induces airway inflammation and systemic oxidative stress, cytotoxicity, and genotoxicity (such as DNA damage). Recent evidence from human and in vitro studies suggests a strong role for oxidative stress caused by free radicals, such as reactive oxygen species (ROS), in the toxicity of laser printer emissions. However, the amount of ROS generated from laser printer nanoparticle emissions and the relative contribution of various fractions (vapors, organics, metals, and metal oxides) have not been investigated to-date. In this study, we aim to quantify short-lived ROS and H₂O₂ laser printer emissions, as well as the relative contribution of various fractions of LPEs in ROS generation. An aerosol chamber with HEPA filtered air was used to generate LPE emissions from one representative printer. In separate experiments, size fractionated LPEs were collected on filters (particles) or impingers (particles and vapors). The nanoscale fraction of LPEs (PM_0.1) was further separated into the organic fraction and inorganic (transition metals/metal oxides) following a sequence of extraction with solvents and centrifugation. The short-lived ROS and H₂O₂ generated from each fraction were quantified with an acellular Trolox-based liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS) method recently developed in our lab. The particulate fraction of LPEs PM_0.1 generated 2.68 times more total ROS (sum of short-lived ROS and H₂O₂) than the vapor fraction. In tested LPEs, transition metal oxides, which constituted 3% by mass, produced 69× and 202× times more short-lived ROS and H₂O₂, respectively, on a mass basis, than the organic fraction. Furthermore, fresh PM_0.1 generated 282× and 32× times more short-lived ROS and H₂O₂, respectively, than aged and processed PM_0.1. We conclude that transition metal oxides, albeit a minor constituent of the LPE PM_0.1 emissions, are the species responsible for the majority of acellular ROS in this printer. A larger range of printers should be tested in the future. Because transition metal oxides in toners originate primarily from engineering nanomaterials (ENMs) in printer toner powder, reformulation of toner powders to contain less of these ROS active metals is recommended.

Nontarget Screening Reveals Time Trends of Polar Micropollutants in a Riverbank Filtration System

The historic emissions of polar micropollutants in a natural drinking water source were investigated by nontarget screening with high-resolution mass spectrometry and open cheminformatics tools. The study area consisted of a riverbank filtration transect fed by the river Lek, a branch of the lower Rhine, and exhibiting up to 60-year travel time. More than 18,000 profiles were detected. Hierarchical clustering revealed that 43% of the 15 most populated clusters were characterized by intensity trends with maxima in the 1990s, reflecting intensified human activities, wastewater treatment plant upgrades and regulation in the Rhine riparian countries. Tentative structure annotation was performed using automated in silico fragmentation. Candidate structures retrieved from ChemSpider were scored based on the fit of the in silico fragments to the experimental tandem mass spectra, similarity to openly accessible accurate mass spectra, associated metadata, and presence in a suspect list. Sixty-seven unique structures (72 over both ionization modes) were tentatively identified, 25 of which were confirmed and included contaminants so far unknown to occur in bank filtrate or in natural waters at all, such as tetramethylsulfamide. This study demonstrates that many classes of hydrophilic organics enter riverbank filtration systems, persisting and migrating for decades if biogeochemical conditions are stable.

Nitric Oxide Modulates Metabolic Remodeling in Inflammatory Macrophages through TCA Cycle Regulation and Itaconate Accumulation

Classical activation of macrophages (M(LPS+IFNγ)) elicits the expression of inducible nitric oxide synthase (iNOS), generating large amounts of NO and inhibiting mitochondrial respiration. Upregulation of glycolysis and a disrupted tricarboxylic acid (TCA) cycle underpin this switch to a pro-inflammatory phenotype. We show that the NOS cofactor tetrahydrobiopterin (BH4) modulates IL-1β production and key aspects of metabolic remodeling in activated murine macrophages via NO production. Using two complementary genetic models, we reveal that NO modulates levels of the essential TCA cycle metabolites citrate and succinate, as well as the inflammatory mediator itaconate. Furthermore, NO regulates macrophage respiratory function via changes in the abundance of critical N-module subunits in Complex I. However, NO-deficient cells can still upregulate glycolysis despite changes in the abundance of glycolytic intermediates and proteins involved in glucose metabolism. Our findings reveal a fundamental role for iNOS-derived NO in regulating metabolic remodeling and cytokine production in the pro-inflammatory macrophage.

Profiling of Human Milk Oligosaccharides for Lewis Epitopes and Secretor Status by Electrostatic Repulsion Hydrophilic Interaction Chromatography Coupled with Negative-Ion Electrospray Tandem Mass Spectrometry

Human milk oligosaccharides (HMOs) are one of the most abundant ingredients in breast milk, and they play a beneficial role for newborns and are important for infant health. The peripheral fucosylated sequences of HMOs, such as the histo-blood group ABH(O) and Lewis a, b, x, and y antigens, are determined by the expression of the secretor (Se) and Lewis (Le) genes in the mammary gland, and are often the recognition motifs and serve as decoy receptors for microbes. In this work, we developed a method for determination of secretor status and Lewis blood phenotype and assignment of Lewis blood-group epitopes. The method was based on electrostatic repulsion/hydrophilic interaction chromatography coupled with tandem mass spectrometry (ERLIC-MS/MS). A specifically designed stationary phase, aspartic acid-bonded silica (ABS), was used to separate the acidic and neutral HMOs by electrostatic repulsion followed by HILIC. Negative-ion electrospray MS/MS was then used for analysis of secretor status and Lewis blood phenotypes and assignment of important epitopes of HMOs from the lactating mothers by selecting a specific set of unique fragment ions.

Occurrence, Seasonal Variation and Risk Assessment of Antibiotics in the Surface Water of North China

In this study, the occurrence, seasonal, and spatial variations of four classes antibiotics were investigated in the surface water of North China. Water samples were taken from 24 sampling sites along rivers in May and August and antibiotics in water samples were detected by SPE-UPLC-MS/MS. The occurrence of all antibiotics except for FLO in May were higher than in August. The mean concentrations of four classes antibiotics detected in May and August were in the following order respectively: quinolones (421.23 ng/L) > tetracyclines (28.37 ng/L) > amphenicols (20.38 ng/L) > sulfonamides (5.79 ng/L) and amphenicols (284.36 ng/L) > quinolones (15.74 ng/L) > tetracyclines (3.05 ng/L) > sulfonamides (0.20 ng/L). The results showed that quinolones and amphenicols were dominant antibiotics among four classes antibiotics. To explore the source of antibiotics from the fish ponds nearby, antibiotic concentration data, which was investigated in the sediment, fish feed and fish revealed a direct relationship between the main antibiotics and fish farms along the rivers. Risk assessment data indicated enrofloxacin and florfenicol could cause higher safety risks to aquatic organisms compared to other antibiotics.

Phthalates and organophosphorus insecticide residues in shrimp determined by liquid/gas chromatography-Tandem mass spectrometry and a health risk assessment

Shrimps are the most widely and increasingly cultured crustaceans in land-based ponds in Taiwan. However, few studies have investigated the phthalate contamination of and insecticide residues in shrimp. In this study, we applied a validated method to analyze the phthalate and 18 insecticides residues in shrimp. A total of 46 samples of whiteleg, grass, or giant river shrimp were collected from aquafarms and production areas in Taiwan. We detected 0.02-0.70 mg/kg of di-2-ethylhexyl phthalate (DEHP) in three shrimps; 0.02-0.03 mg/kg of chlorpyrifos in three shrimps, and 0.03 mg/kg of trichlorfon in one shrimp, indicating that 6.52% and 8.70% of the samples contained phthalate and insecticide residues, respectively. Furthermore, the assessed risk was negligible and indicated no immediate health risk associated with shrimp consumption. Continual monitoring of the residues in shrimps is critical for further assessment of possible effects on human health.

LC-MS/MS analysis and network pharmacology of Trigonella foenum-graecum - A plant from Ayurveda against hyperlipidemia and hyperglycemia with combination synergy

BACKGROUND

The seed of Trigonella foenum-graecum L. (Methika in Sanskrit) is a well known kaphahara (balancing kapha) herb in Ayurveda indicated in Prameha or early diabetes mellitus. It is also useful in obesity and reduces lipid level of blood.

PURPOSE

We aimed to explore the metabolites present in the plant extract and to establish the combination synergy and the network pharmacology along with the underlying the mechanism of action involved.

STUDY DESIGN

LC-MS/MS based metabolite screening followed by ADME screening and finally network pharmacology exploration of the mechanism of action involved against hyperlipidemia and hypolipidemia with neighbourhood based combination synergy approach.

METHODS

Ethanolic extract of Trigonella foenum-graecum L. (TFHE) was subjected to LC-MS/MS analysis to identify the active constituents. Oral bioavailability and drug likeness was screened for all the compounds. Databases- Binding DB, DAVID, KEGG and STRING were used to gather information to develop the networks. The networks were constructed using Cytoscape 3.2.1. Combination synergy analysis was performed with the help of Cytoscape network analyzer tool with neighbourhood approach.

RESULTS

The LC-MS/MS analysis identified 13 compounds which were found to be bio-available and drug like following the QED and Veber drug likeness parameters. The pathway analysis showed enrichment for different pathways like MAPK pathway (p-4.69E-07), JAK-STAT pathway (p-6.30E-05), Adipocytokine (p-0.00179), Type 2 Diabetes mellitus (0.00441), Insulin signalling pathway (p-0.0121), mTOR signalling pathway (p-0.000378), which are all connected to hyperlipidemia and hyperglycemia. The combination synergy network identified 23 targets interacting with 13 compounds based on a network neighbourhood approach.

CONCLUSION

The network pharmacology analysis strongly suggested the multimode evidences that TFHE largely works on the insulin signalling pathway and mainly based on its antioxidant potential due to its interaction with carbonic anhydrase. Various compounds were found to be interacting with key proteins that activates EGFR/AKT/mTOR signalling cascade which has therapeutic implication in hyperglycemia and hyperlipidemia. The combination synergy network analysis based on neighbourhood approach can help us in further understanding mechanism of multi-molecular fixed dose combinations.

Variability and profiles of lipophilic toxins in bivalves from Great Britain during five and a half years of monitoring: azaspiracids and yessotoxins

Cefas has been responsible for the delivery of official control biotoxin testing of bivalve molluscs from Great Britain for just over a decade. Liquid chromatography tandem mass spectrometric (LC-MS/MS) methodology has been used for the quantitation of lipophilic toxins (LTs) since 2011. The temporal and spatial distribution of okadaic acid group toxins and profiles in bivalves between 2011 and 2016 have been recently reported. Here we present data on the two other groups of regulated lipophilic toxins, azaspiracids (AZAs) and yessotoxins (YTXs), over the same period. The latter group has also been investigated for a potential link with Protoceratium reticulatum and Lingulodinium polyedra, both previously recognised as YTXs producing phytoplankton. On average, AZAs were quantified in 3.2% of all tested samples but notable inter-annual variation in abundance was observed. The majority of all AZA contaminated samples were found between July 2011 and August 2013 in Scotland, while only two, three-month long, AZA events were observed in 2015 and 2016 in the south-west of England. Maximum concentrations were generally reached in late summer or early autumn. Reasons for AZAs persistence during the 2011/2012 and 2012/2013 winters are discussed. Only one toxin profile was identified, represented by both AZA1 and AZA2 toxins at an approximate ratio of 2 : 1, suggesting a single microalgal species was the source of AZAs in British bivalves. Although AZA1 was always the most dominant toxin, its proportion varied between mussels, Pacific oysters and surf clams. The YTXs were the least represented group among regulated LTs. YTXs were found almost exclusively on the south-west coast of Scotland, with the exception of 2013, when the majority of contaminated samples originated from the Shetland Islands. The highest levels were recorded in the summer months and followed a spike in Protoceratium reticulatum cell densities. YTX was the most dominant toxin in shellfish, further strengthening the link to P. reticulatum as the YTX source. Neither homo-YTX, nor 45-OH homo-YTX were detected throughout the monitored period. 45-OH YTX, thought to be a shellfish metabolite associated with YTX elimination, contributed on average 26% in mussels. Although the correlation between 45-OH YTX abundance and the speed of YTX depuration could not be confirmed, we noted the half-life of YTX was more than two-times longer in queen scallops, which contained 100% YTX, than in mussels. No other bivalve species were affected by YTXs. This is the first detailed evaluation of AZAs and YTXs occurrences and their profiles in shellfish from Great Britain over a period of multiple years.

[Effect of N-acetyl-L-cysteine on bioavailability and brain distribution of curcumin by nasal delivery]

Curcumin( Cur) is a natural active substance extracted from the roots or tubers of traditional Chinese medicinal materials. It has anti-inflammatory and anti-tumor activities on brain diseases. Due to the poor stability,low solubility,poor absorption and low bioavailability of curcumin,N-acetyl-L-cysteine( NAC) was used as an absorption enhancer and mixed with curcumin to improve the absorption of curcumin in the body. In this paper,curcumin was smashed by airflow pulverization,and Cur-NAC mixtures were prepared by being grinded with liquid. Then,the raw material and the product were analyzed by differential scanning calorimetry( DSC),X-ray diffraction( XRD) for structural characterization. The dissolution was determined by high performance liquid chromatography( HPLC) analysis. The characteristic peaks of the samples prepared by grinding method were similar to those of the raw materials,while the melting temperature and the accumulated dissolution degree were not significantly changed. The crystal forms of the products were not changed,and no new crystal form was formed after grinding. After the administration of intranasal powder,blood samples were collected from the orbit,while the whole brain tissues were removed from the skull and dissected into 10 anatomical regions. The concentrations of curcumin in these samples were determined by UPLC-MS/MS. The concentrations of curcumin in plasma and brain were compared at different time points. After intranasal administration of two drugs,it was found that the concentration of curcumin after sniffing up the mixtures in plasma was high,and the concentration of the drug in the olfactory bulb,hippocampus,and pons was increased significantly. Within 0. 083-0. 5 h,the olfactory bulb,piriform lobe and hippocampus remained high concentrations,the endodermis,striatum,hypothalamus and midbrain reached high concentrations within 1-3 h; and the cerebellum,pons and brain extension maintained relatively high concentrations within 3-7 h. The experiment showed that nasal administration of Cur-NAC mixtures can significantly improve the bioavailability of curcumin,and lead to significant differences in brain tissue distribution.

Discovery of a Novel Connecting Link between Renin-Angiotensin System and Cancer in Barrett's Esophagus by Proteomic Screening

The renin-angiotensin system (RAS) plays a central role in the regulation of homeostasis and blood pressure. This involves an important enzyme called angiotensin-converting enzyme that leads to the conversion of angiotensin I into angiotensin II. RAS has been reported to show association with inflammation, and in sporadic studies, with cancer. In particular, angiotensin II has been reported to be prevalent in the hypoxic microenvironment and associated with cancer signaling pathways. In a recent study, Bratlie et al. (Proteomics Clin. Appl. 2019, 4, 1800102) is shown to exploit 2D gel electrophoresis, and mass spectrometry (MS) to identify differentially expressed proteins by comparing low-grade dysplasia in Barrett's Esophagus (BE) following administration of agents that interfere with RAS, that is, enalapril and candesartan, and identified specific modulation of HSP60, PDIA3, and PPA1. Though 2D gel coupled with MS is a commonly-used tool for studying proteomes, it still has limitations in terms of a comprehensive analysis due to lack of absolute quantitation in a high-throughput manner. Despite technical limitations and the small size of the study, preliminary data emerging from the investigation show interference caused by clinically approved RAS inhibitors resulting in alteration of molecular markers associated with tumorigenicity. The authors propose potential factors that may influence the progression of the disease. However, these are conspicuous changes in high-abundance proteins only. Therefore, there is a need to carry out detailed experimental studies either using an in vitro labeling technique (isobaric labeling for relative and absolute quantitation) for tissues or an in vivo labeling technique (stable isotope labeling in animal cell culture) coupled with LC-MS/MS to identify differentially-regulated proteins to delineate the role of RAS in BE.

Melatonin as an inhibitor of sweet cherries ripening in orchard trees

Although melatonin effects on postharvest fruit ripening have been studied in some detail, information is still scarce during pre-harvest. Here, we examined whether or not melatonin may exert a regulatory role during sweet cherries ripening in orchard trees. We evaluated (i) the endogenous variations in melatonin contents, in comparison to those of well-known phytohormones such as ABA, salicylic acid and jsamonic acid, by ultrahigh performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) during fruit ripening over two consecutive years, and (ii) to what extent melatonin treatments at low and high concentrations (at 10^-4 M and 10^-5 M, respectively) influence fruit ripening on the tree. Endogenous melatonin contents decreased in parallel to those of salicylic acid and jasmonic acid, while ABA contents increased as fruit ripening progressed, thus suggesting an inhibitory role for melatonin in fruit ripening. Furthermore, melatonin treatment at 10^-5 M, which transiently increased endogenous melatonin contents at physiological concentrations, delayed anthocyanin accumulation, thus confirming an inhibitory regulatory role for melatonin in fruit ripening. We also found that the endogenous contents of cytokinins, but not those of ABA were transiently affected by melatonin treatment at 10^-5 M. It is concluded that melatonin may delay sweet cherries ripening in orchard trees, probably exerting a modulatory role through a hormonal cross-talk. These results have important implications for the use of melatonin in the control of the timing of sweet cherries ripening in orchard trees.

The antifungal activity and mechanisms of action of quantified extracts from berries, leaves and roots of Phytolacca tetramera

BACKGROUND

Phytolacca tetramera is an endemic plant from Argentina that is currently at serious risk because its environment is subjected to a high anthropic impact. A previous study has shown that berry extracts obtained from this plant display antifungal activity against multiple human-pathogenic fungi when tested with a non-standardized method. Further evidences of the antifungal properties of other parts of the plant and studies of mechanism of antifungal action of the antifungal chemically characterized extracts are required.

PURPOSE

This study aimed to gain further evidence of the antifungal activity of P. tetramera berry, leaf and root extracts in order to find the most active extract to be developed as an Herbal Medicinal Antifungal Product. The medicinal usefulness of P. tetramera extracts as antifungal agents will serve as an important support to create concience and carry out actions tending to the preservation of this threatened species and its environment.

MATERIALS AND METHODS

Chemical analysis of all P. tetramera extracts, including quantitation of selected markers, was performed through UHPLC-ESI-MS/MS and UPLC-ESI-MS techniques according to the European Medicines Agency (EMA). The antifungal activity of the quantified extracts was tested with the standardized CLSI microbroth dilution method against Candida spp. Antifungal mechanisms of the most active extract were studied by examination of morphological changes by phase-contrast and fluorescence microscopies and both, cellular and enzymatic assays targeting either the fungal membrane or the cell wall.

RESULTS

The antifungal activity of twelve P. tetramera extracts was tested against Candida albicans and Candida glabrata. The dichloromethane extract from berries (PtDEb) showed the best activity. Phytolaccagenin (PhytG) and phytolaccoside B (PhytB) were selected as the main active markers for the antifungal P. tetramera extracts. The quantitation of these active markers in all extracts showed that PtDEb possessed the highest amount of PhytG and PhytB. Finally, studies on the mechanism of antifungal action showed that the most active PtDEb extract produces morphological changes compatible with a damage of the cell wall and/or the plasma membrane. Cellular and enzymatic assays showed that PtDEb would not damage the fungal cell wall by itself, but would alter the plasma membrane. In agreement, PtDEb was found to bind to ergosterol, the main sterol of the fungal plasma membrane.

CONCLUSION

Studies of the anti-Candida activity of P. tetramera extracts led to the selection of PtDEb as the most suitable extract, confirming the antifungal properties of the threatened species P. tetramera. The new data give a valuable reason for the definitive protection of this sp. and its natural environment thus allowing further studies for the future development of an Herbal Medicinal Antifungal Product.

Submodular Generalized Matching for Peptide Identification in Tandem Mass Spectrometry

MOTIVATION

Identification of spectra produced by a shotgun proteomics mass spectrometry experiment is commonly performed by searching the observed spectra against a peptide database. The heart of this search procedure is a score function that evaluates the quality of a hypothesized match between an observed spectrum and a theoretical spectrum corresponding to a particular peptide sequence. Accordingly, the success of a spectrum analysis pipeline depends critically upon this peptide-spectrum score function. We develop peptide-spectrum score functions that compute the maximum value of a submodular function under $m$ m matroid constraints. We call this procedure a submodular generalized matching (SGM) since it generalizes bipartite matching. We use a greedy algorithm to compute maximization, which can achieve a solution whose objective is guaranteed to be at least $\frac{1}{1+m}$ 1 1 + m of the true optimum. The advantage of the SGM framework is that known long-range properties of experimental spectra can be modeled by designing suitable submodular functions and matroid constraints. Experiments on four data sets from various organisms and mass spectrometry platforms show that the SGM approach leads to significantly improved performance compared to several state-of-the-art methods. Supplementary information, C++ source code, and data sets can be found at https://melodi-lab.github.io/SGM.

A pilot metabolomics study of tuberculosis immune reconstitution inflammatory syndrome

BACKGROUND

Diagnosis of paradoxical tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is challenging and new tools are needed for early diagnosis as well as to understand the biochemical events that underlie the pathology in TB-IRIS.

METHODS

Plasma samples were obtained from participants from a randomized HIV/TB treatment strategy study (AIDS Clinical Trials Group [ACTG] A5221) with (n = 26) and without TB-IRIS (n = 22) for an untargeted metabolomics pilot study by liquid-chromatography mass spectrometry. The metabolic profile of these participants was compared at the study entry and as close to the diagnosis of TB-IRIS as possible (TB-IRIS window). Molecular features with p < 0.05 and log2 fold change ≥0.58 were submitted for pathway analysis through MetaboAnalyst. We also elucidated potential metabolic signatures for TB-IRIS using a LASSO regression model.

RESULTS

At the study entry, we showed that the arachidonic acid and glycerophospholipid metabolism were altered in the TB-IRIS group. Sphingolipid and linoleic acid metabolism were the most affected pathways during the TB-IRIS window. LASSO modeling selected a set of 8 and 7 molecular features with the potential to predict TB-IRIS at study entry and during the TB-IRIS window, respectively.

CONCLUSION

This study suggests that the use of plasma metabolites may distinguish HIV-TB patients with and without TB-IRIS.

Large-Scale Identification and Fragmentation Pathways Analysis of N-Glycans from Mouse Brain

N-linked glycosylation is one of the most common protein PTMs, and the topological structure (monosaccharide composition and sequence as well as glycosidic linkages) of N-glycans is vital information to understand their biological functions and roles. Tandem mass spectrometry has been widely used for topological structure characterization of N-glycans, where comprehensive understanding of fragmentation pathways and characteristics of product ions are essential to achieve best interpretation of MS/MS data and highest confidence of identification. Here, we report our glycomic study of N-glycome of mouse brain as well as fragmentation pathway analysis of the identified N-glycans. With LC-MS/MS analysis at both the positive and negative ESI modes together with our recently developed N-glycan database search engine GlySeeker, 221 unique N-glycans with putative topological structures were identified with target-decoy searches and number of best hits of 1. Analysis of fragmentation pathways and characteristics of product ions of permethylated N-glycans in the positive mode and native N-glycans in the negative mode were further carried out. The reported N-glycans serve as a basic reference for future glycosylation study of mouse brain; and in general database search of tandem mass spectra of N-glycans, B/Y/Z ions should be preferentially considered for the permethylated form in the positive mode and B/C/Z ions for the native form in the negative mode.

Development and validation of a stability-Indicating RP-HPLC method for simultaneous estimation of sofosbuvir and velpatasvir in fixed dose combination tablets and plasma

A simple, specific, sensitive, robust, accurate and precise reverse-phase high performance liquid chromatographic (RP-HPLC) method was developed and validated for simultaneous determination of sofosbuvir (SOF) and velpatasvir (VLP) in fixed dose combination tablets and plasma. Validation parameters, such as system suitability, accuracy, inter-day and intra-day variances, specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), robustness and stability were assessed following the standards set by the International Conference on Harmonization (ICH). The isocratic elution of SOF and VLP was carried out under ambient conditions using ammonium acetate buffer (pH = 7.0), acetonitrile and methanol (20:40:40, v/v/v) as mobile phase flowing through a Promosil C18 column at a flow rate of 1.0 mL/min. The average retention time of SOF and VLP was 3.72 min and 7.09 min, respectively. The LOD and LOQ of SOF were 0.23μg/mL and 2.48μg/mL, respectively; while those of VLP were 0.70μg/mL and 7.52μg/mL, respectively. The regression coefficient (r2) was 0.998. The relative standard deviation (RSD) was less than 2% for precision. The recovery of both the analytes remained within 100±1%. All other validation parameters complied with ICH guidelines. The analytes remained stable throughout the analytical procedure. Moreover, this method was successfully applied to assess the in vitro dissolution of SOF and VLP loaded fixed dose combination tablets. Same method with same mobile phase was applied on rat plasma and there was no interference.

Comparative and chemometric analysis of correlations between the chemical fingerprints and anti-proliferative activities of ganoderic acids from three Ganoderma species

INTRODUCTION

Investigation on ganoderic acids (GAs) from different cultivars and origins of Ganoderma species, regarding to their composition, contents and bioactivities, will be of great importance for the development and quality control of Ganoderma-based healthcare products or drugs.

OBJECTIVE

Comparative and chemometric analysis of different Ganoderma species were conducted to reveal the correlations between their chemical fingerprints and anti-proliferative activities.

METHODOLOGY

Six Ganoderma samples with different origins and parts of fruiting body (pileus and stipe) were extracted with chloroform and enriched by a SPE-C18 cartridge. The eluents were used for high-performance liquid chromatography ultraviolet electrospray ionisation tandem mass spectrometry (HPLC-UV/ESI-MS/MS) analysis and cytotoxicity assay with three cancer cell lines (SGC-7901, HT-29 and Hep G2). Chemometric analysis was applied to correlate their chemical compositions and corresponding bioactivities.

RESULTS

Sixteen peaks (accounting for 70% of the total peak areas) were identified as GAs, and their contents ranged from 0.368 to 10.8 μg/g in various Ganoderma species. The extracts from three Ganoderma species had significant anti-proliferative activities (inhibitory rates ranged from 70.8% to 80.7%), and extracts from Lurongzhi showed remarkable inhibition to all three cancer cells (inhibitory rates range from 81.6% to 92.1%). Finally, chemometric analysis revealed that 3,7,12-trihydroxy-4,4,14-trimethyl-11,15-dioxochol-8-en-24-oic acid and 12-acetoxy-15-hydroxy-4,4,14-trimethyl-3,7,11-trioxochol-8-en-24-oic acid were the two compounds with most potential anti-proliferative activity for SGC-7901.

CONCLUSION

The correlations between chemical fingerprints and anti-proliferative activities of various Ganoderma species give remarkable insight into the true bioactive components of chemical markers for the quality assessment of the Ganoderma resources, and provide a good guidance for the study on the chemical spectrum-bioactivity relationship.

Metabolomics in the Diagnosis of Pheochromocytoma and Paraganglioma

Metabolomics refers to the detection and measurement of small molecules (metabolites) within biological systems, and is therefore a powerful tool for identifying dysfunctional cellular physiologies. For pheochromocytomas and paragangliomas (PPGLs), metabolomics has the potential to become a routine addition to histology and genomics for precise diagnostic evaluation. Initial metabolomic studies of ex vivo tumors confirmed, as expected, succinate accumulation in PPGLs associated with pathogenic variants in genes encoding succinate dehydrogenase subunits or their assembly factors (SDHx). Metabolomics has now shown utility in clarifying SDHx variants of uncertain significance, as well as the accurate diagnosis of PPGLs associated with fumarate hydratase (FH), isocitrate dehydrogenase (IDH), malate dehydrogenase (MDH2) and aspartate transaminase (GOT2). The emergence of metabolomics resembles the advent of genetic testing in this field, which began with single-gene discoveries in research laboratories but is now done by standardized massively parallel sequencing (targeted panel/exome/genome testing) in pathology laboratories governed by strict credentialing and governance requirements. In this setting, metabolomics is poised for rapid translation as it can utilize existing infrastructure, namely liquid chromatography-tandem mass spectrometry (LC-MS/MS), for the measurement of catecholamine metabolites. Metabolomics has also proven tractable to in vivo diagnosis of SDH-deficient PPGLs using magnetic resonance spectroscopy (MRS). The future of metabolomics - embedded as a diagnostic tool - will require adoption by pathologists to shepherd development of standardized assays and sample preparation, reference ranges, gold standards, and credentialing.

Simultaneous determination of resibufogenin and its eight metabolites in rat plasma by LC-MS/MS for metabolic profiles and pharmacokinetic study

BACKGROUND

Resibufogenin is one of the main active compounds of Venenum Bufonis and exhibits diverse pharmacological activities. It is brought into focus for its potency in heart failure and cancer therapy.

PURPOSE

The purpose of this study was to establish a convenient and effective method which was used to simultaneously determine the resibufogenin and its metabolites in rat plasma for further understanding the metabolic profiles of resibufogenin in vivo and pharmacokinetic study by LC-MS/MS.

METHODS

The analytes were separated on a BEH C18 column with a mobile phase of water containing 0.05% formic acid and acetonitrile under gradient elution at a flow rate of 0.4 ml/min. Resibufogenin and its eight metabolites were quantified in positive electrospray ionization and MRM mode with transitions of m/z 385.5→349.2 for resibufogenin; m/z 513.7→145.3 for IS (internal standard); m/z 401.23→365.21, m/z 417.23→285.21 and m/z 385.24→349.21 for three main metabolites (hydroxylated-resibufogenin; dihydroxylated-resibufogenin and 3-epi-resibufogenin, respectively).

RESULTS

This method was successfully validated with a good linearity over the concentration ranges of 1-200 ng/ml for resibufogenin and the correlation coefficients was more than 0.990. The lower limit of quantification was 1 ng/ml and the precision and accuracy values were less than 15%. The method was applied to study the metabolic profiles of resibufogenin in rat plasma after oral administration of 20 mg/kg. The results indicated that the metabolic reactions of resibufogenin were mainly hydroxylation, dihydroxylation, dehydrogenation and isomerization. Totally eleven metabolites were identified, among which eight were successfully quantified.

CONCLUSION

The results could provide further research foundation for the mechanisms study of activity and toxicity in vivo and facilitate the appropriate clinical application of resibufogenin.