Search results for "High Pressure"
showing 10 items of 894 documents
Optimised method for the analysis of phenolic compounds from caper (Capparis spinosa L.) berries and monitoring of their changes during fermentation
2016
In this work, an ad hoc method to identify and quantify polyphenols from caper berries was developed on high-performance liquid chromatography/electrospray ionisation source/mass spectrometry (HPLC-ESI-MS). The method was applied during fermentation carried out with Lactobacillus pentosus OM13 (Trial S) and without starter (Trial C). A total of five polyphenols were identified. All samples contained high concentrations of rutin. Epicatechin was found in untreated fruits, on the contrary quercetin was detected during fermentation. Trial S was characterised by a more rapid acidification and lower levels of spoilage microorganisms than Trial C. L. pentosus dominated among the microbial communi…
Effect of high pressure on the antimicrobial activity and secondary structure of the bacteriocin nisin
2018
International audience; Effect of high pressure (HP) treatment on the antimicrobial properties and the structure of nisin was evaluated. Nisin solutions at pH 2.8 or 6.1 were treated by HP at 500 MPa – 10 min – 20 °C and their antimicrobial potency was determined. It appeared that HP clearly impacted the antimicrobial activity of nisin, with respective activity loss of 22.5% and 49.9% at pH 2.8 and 6.1. Structural analysis of nisin by circular dichroism and Fourier transform-infrared spectroscopies revealed that the decrease of nisin antimicrobial activity was likely due to the unfolding of the protein induced by HP. A loss of nisin β-turns structure, particularly significant at neutral pH,…
Stabilization and detection of hydrophylloquinone as di-O-methyl derivative
2016
Phylloquinone is a redox active naphthoquinone involved in electron transport in plants. The function of this reduced form remains unclear due to its instability, which has precluded detection. Herein, a simple method that permits the stabilization of the reduced form of phylloquinone by di-O-methylation and HPLC detection is described. Fil: Sussmann, Rodrigo A. C.. Universidade de Sao Paulo; Brasil Fil: de Moraes, Marcilio M.. Universidade de Sao Paulo; Brasil Fil: Cebrián Torrejón, Gerardo. Universidad de Valencia; España. Universidade de Sao Paulo; Brasil Fil: Porta, Exequiel Oscar Jesús. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - …
Formation of 2-nitrophenol from salicylaldehyde as a suitable test for low peroxynitrite fluxes
2016
There has been some dispute regarding reaction products formed at physiological peroxynitrite fluxes in the nanomolar range with phenolic molecules, when used to predict the behavior of protein-bound aromatic amino acids like tyrosine. Previous data showed that at nanomolar fluxes of peroxynitrite, nitration of these phenolic compounds was outcompeted by dimerization (e.g. biphenols or dityrosine). Using 3-morpholino sydnonimine (Sin-1), we created low fluxes of peroxynitrite in our reaction set-up to demonstrate that salicylaldehyde displays unique features in the detection of physiological fluxes of peroxynitrite, yielding detectable nitration but only minor dimerization products. By mean…
High-Performance Liquid Chromatography/Electrospray Ionization Tandem Mass Spectrometry (HPLC-ESI-MSn) Analysis and Bioactivity Useful for Prevention…
2019
This study aimed at evaluating and comparing the chemical profile obtained by HPLC-ESI-MSn analysis, the inhibitory activity of enzymes linked to obesity (α-amylase, α-glucosidase, and lipase) and the antioxidant properties (DPPH, ABTS, FRAP, and β-carotene bleaching tests) of ethanol extracts of bulbs (BE) and aerial parts (APE) from Allium commutatum Guss. (known in Italy as “aglio delle isole”). The chemical profile revealed alliin as the main abundant compound with values of 31.5 and 38.8 mg/g extract for BE and APE, respectively. APE is rich also in quercetin (38.5 mg/g extract) and luteolin (31.8 mg/g extract). Bulbs extract exhibited the highest activity as inhibitor of enzymes linke…
FragClust and TestClust, two informatics tools for chemical structure hierarchical clustering analysis applied to lipidomics. The example of Alzheime…
2016
Lipidomic analysis is able to measure simultaneously thousands of compounds belonging to a few lipid classes. In each lipid class, compounds differ only by the acyl radical, ranging between C10:0 (capric acid) and C24:0 (lignoceric acid). Although some metabolites have a peculiar pathological role, more often compounds belonging to a single lipid class exert the same biological effect. Here, we present a lipidomics workflow that extracts the tandem mass spectrometry data from individual files and uses them to group compounds into structurally homogeneous clusters by chemical structure hierarchical clustering analysis (CHCA). The case-to-control peak area ratios of the metabolites are then a…
7,8-hydroxy-2′-deoxyguanosine/2′-deoxiguanosine ratio determined in hydrolysates of brain DNA by ultrachromatrography coupled to tandem mass spectrom…
2017
7,8-hydroxy-2'-deoxyguanosine (8-OHdG) is an abundant DNA lesion formed by oxidation of the nucleoside 2'-deoxyguanosine (2-dG) and one of the most studied and accepted oxidative stress biomarkers. 8-OHdG has a strong carcinogenic potential, and prolonged oxidative stress heightens pathological conditions and especially cancer risk. Our aim was to develop, validate and apply a reliable method to assess DNA oxidation in genomic cellular DNA of sensible target organs such as brain. A procedure to isolate and digest the DNA of brain tissue properly for further detection of 8-OHdG and 2-dG by Ultra Performance Liquid Chromatography tandem Mass Spectrometry (UPLC-MS/MS) was optimized. The UPLC-M…
Mucoadhesive solid lipid microparticles for controlled release of a corticosteroid in the chronic obstructive pulmonary disease treatment.
2017
Therapeutic efficacy of inhaled drugs is limited by rapid clearance from the site of action due to absorption into systemic circulation or metabolic degradation by alveolar macrophages. Drug delivery systems offer new solutions to clinical problems especially in the treatment of pulmonary diseases. In particular, Solid Lipid Microparticles (SLM) in the range of 3-5 µm are suggested as systems for delivery of therapeutics to the lung as, because of their size, they are able to deposit into secondary bronchi, avoiding systemic absorption typical of alveolar regions. Here, we describe two novel different SLMs prepared with chitosan and alginate for sustained release of fluticasone propionate (…
Bioactive triterpenes of protium heptaphyllum gum resin extract display cholesterol-lowering potential
2021
Hypercholesterolemia is one of the major causes of cardiovascular disease, the risk of which is further increased if other forms of dyslipidemia occur. Current therapeutic strategies include changes in lifestyle coupled with drug administration. Statins represent the most common therapeutic approach, but they may be insufficient due to the onset of resistance mechanisms and side effects. Consequently, patients with mild hypercholesterolemia prefer the use of food supplements since these are perceived to be safer. Here, we investigate the phytochemical profile and cholesterol-lowering potential of Protium heptaphyllum gum resin extract (PHE). Chemical characterization via HPLC-APCI-HRMS2 and…
In vivo effect of N-ethylmaleimide (NEM) on the measurement of nitrate in plasma
2016
Bioavailability of nitric oxide in the body may be estimated by measuring the concentration of nitrate in plasma. However, it has not been reported whether sequestering of aminothiols in plasma affects the concentration of nitrate in the samples.N-ethylmaleimide (NEM) sequesters aminothiols in plasma therefore we tested the in vivo effect of NEM on the concentration nitrate in plasma.Blood samples were collected from 56 healthy subjects in EDTA vials, EDTA vials containing PBS (pH7.4) and EDTA vials containing NEM dissolved in PBS. Nonparametric statistical tests were used to study the effect of NEM on the concentration of nitrate in plasma measured by the Griess reagent assay and by an HPL…