Search results for " SPECT"
showing 10 items of 11464 documents
Trichomonicidal and parasite membrane damaging activity of bidesmosic saponins from Manilkara rufula.
2017
The infection caused by Trichomonas vaginalis is the most common but overlooked non-viral sexually transmitted disease worldwide. Treatment relies on one class of drugs, the 5-nitroimidazoles, but resistance is widespread. New drugs are urgently needed. We reported the effect of crude and purified saponin fractions of Manilkara rufula against Trichomonas vaginalis. The compound responsible for antitrichomonal activity was isolated and identified as an uncommon bidesmosic saponin, Mi-saponin C. This saponin eliminated parasite viability without toxicity against the human vaginal epithelial line (HMVII). In addition, the isolated saponin fraction improved the metronidazole effect against a me…
Null mutants of Candida albicans for cell-wall-related genes form fragile biofilms that display an almost identical extracellular matrix proteome.
2016
By two-dimensional gel electrophoresis (2-DE) and mass spectrometry, we have characterized the polypeptide species present in extracts obtained by 60% ethanol treatment of whole mature (48 h) biofilms formed by a reference strain (CAI4- URA3 ) and four Candida albicans null mutants for cell-wall-related genes ( ALG5, CSA1, MNN9 and PGA10) . Null mutants form fragile biofilms that appeared partially split and weakly attached to the substratum contrary to those produced by the reference strain. An almost identical, electrophoretic profile consisting of about 276 spots was visualized in all extracts examined. Proteomic analysis led to the identification of 131 polypeptides, corresponding to 86…
Microorganism adhesion using silicon dioxide: An experimental study
2020
In this study, spectrophotometry was used to measure changes in the absorbance properties of yeast, Gram-positive, and Gram-negative bacteria after their attachment to silicon dioxide microparticles (silica). The goal of this study was to determine whether spectrophotometry is an effective method to distinguish these microorganisms from one another and determine whether they have an affinity for silicon dioxide. The experiments were performed by examining the light absorption properties of yeast, Gram-positive and Gram-negative bacteria in a spectrophotometer, both with and without silicon dioxide microparticles. The experiments produced a number of promising results. First, the spectrophot…
Pressure effects on α-synuclein amyloid fibrils: An experimental investigation on their dissociation and reversible nature
2017
αâsynuclein amyloid fibrils are found in surviving neurons of Parkinson's disease affected patients, but the role they play in the disease development is still under debate. A growing number of evidences points to soluble oligomers as the major cytotoxic species, while insoluble fibrillar aggregates could even play a protection role. In this work, we investigate αâsynuclein fibrils dissociation induced at high pressure by means of Small Angle X-ray Scattering and Fourier Transform Infrared Spectroscopy. Fibrils were produced from wild type αâsynuclein and two familial mutants, A30P and A53T. Our results enlighten the different reversible nature of αâsynuclein fibrils fragmentati…
Determinants for Tight and Selective Binding of a Medicinal Dicarbene Gold(I) Complex to a Telomeric DNA G-Quadruplex: a Joint ESI MS and XRD Investi…
2016
International audience; The dicarbene gold(I) complex [Au(9-methylcaffein-8-ylidene)(2)]BF4 is an exceptional organometallic compound of profound interest as a prospective anticancer agent. This gold(I) complex was previously reported to be highly cytotoxic toward various cancer cell lines invitro and behaves as a selective G-quadruplex stabilizer. Interactions of the gold complex with various telomeric DNA models have been analyzed by a combined ESI MS and X-ray diffraction (XRD) approach. ESI MS measurements confirmed formation of stable adducts between the intact gold(I) complex and Tel 23 DNA sequence. The crystal structure of the adduct formed between [Au(9-methylcaffein-8-ylidene)(2)]…
Evaluation of Alternaria mycotoxins in strawberries: quantification and storage condition
2016
Alternariol (AOH), alternariol methyl ether (AME) and tentoxin (TEN) are Alternaria mycotoxins produced by the most common post-harvest pathogens of fruits. The production of these metabolites depends on several environmental factors, mainly temperature, water activity, pH and the technological treatments that have been applied to the product. In this study, the occurrence of AOH, AME and TEN was evaluated in strawberries samples stored at different temperatures ranges (at 22 ± 2 or 6 ± 2°C) and different periods (up to 1 month) simulating the current practice of consumer's storage conditions. Sample extraction was performed using a liquid-liquid extraction method prior to LC-MS/MS analysis…
Extraordinary stability of hemocyanins from L. polyphemus and E. californicum studied using infrared spectroscopy from 294 to 20 K
2016
International audience; Hemocyanins are large oligomeric respiratory proteins found in many arthropods and molluscs. Here we give infrared spectroscopic evidence of a high stability towards exposure to sub-zero temperatures for hemocyanins from the arthropods Limulus polyphemus and Eurypelma californicum at different pH values. Small but distinct temperature induced changes of the secondary structure were observed, but a stable core of at least 40% α-helical structure is preserved as identified in the infrared spectra obtained between 294 and 20 K. The structural changes differ in detail somewhat for the two hemocyanins, with overall fewer changes observed in the case of E. californicum. No…
Fast UPLC/PDA determination of squalene in Sicilian P.D.O. pistachio from Bronte: Optimization of oil extraction method and analytical characterizati…
2017
Abstract A fast reversed-phase UPLC method was developed for squalene determination in Sicilian pistachio samples that entry in the European register of the products with P.D.O. In the present study the SPE procedure was optimized for the squalene extraction prior to the UPLC/PDA analysis. The precision of the full analytical procedure was satisfactory and the mean recoveries were 92.8 ± 0.3% and 96.6 ± 0.1% for 25 and 50 mg L−1 level of addition, respectively. Selected chromatographic conditions allowed a very fast squalene determination; in fact it was well separated in ∼0.54 min with good resolution. Squalene was detected in all the pistachio samples analyzed and the levels ranged from 5…
Targeting Bacterial Sortase A with Covalent Inhibitors: 27 New Starting Points for Structure-Based Hit-to-Lead Optimization.
2019
Because of its essential role as a bacterial virulence factor, enzyme sortase A (SrtA) has become an attractive target for the development of new antivirulence drugs against Gram-positive infections. Here we describe 27 compounds identified as covalent inhibitors of
A Vastly Increased Chemical Variety of RNA Modifications Containing a Thioacetal Structure
2018
International audience; Recently discovered new chemical entities in RNA modifications have involved surprising functional groups that enlarge the chemical space of RNA. Using LC-MS, we found over 100 signals of RNA constituents that contained a ribose moiety in tRNAs from E. coli. Feeding experiments with variegated stable isotope labeled compounds identified 37 compounds that are new structures of RNA modifications. One structure was elucidated by deuterium exchange and high-resolution mass spectrometry. The structure of msms2 i6 A (2-methylthiomethylenethio-N6-isopentenyl-adenosine) was confirmed by methione-D3 feeding experiments and by synthesis of the nucleobase. The msms2 i6 A contai…