Search results for "Ionization"
showing 10 items of 1255 documents
Direct identification of microorganisms from thioglycolate broth by MALDI-TOF MS.
2017
We developed an easy MALDI-TOF MS-based assay to identify microorganisms directly from thioglycolate broth. A total of 101 positive thioglycolate broths inoculated with 15 different kinds of samples were evaluated. In 91 samples (90.1%), direct MALDI-TOF MS identifications were the same as those obtained after conventional laboratory procedures including subcultures. In 10 samples misidentified by direct processing, yeasts or mixed cultures grew in the thioglycolate subcultures, or high cellular debris hampered a correct analysis. This rapid method can provide a fast, clinically- relevant species-level identification without disturbing the daily workflow in clinical microbiology laboratorie…
Bistacrine derivatives as new potent antimalarials
2016
Linking two tacrine molecules results in a tremendous increase of activity against Plasmodia in comparison to the monomer. This finding prompted the synthesis of a library of monomeric and dimeric tacrine derivatives in order to derive structure-activity relationships. The most active compounds towards chloroquine sensitive Plasmodium strain 3D7 and chloroquine resistant strain Dd2 show IC50 values in the nanomolar range of concentration, low cytotoxicity and target the cysteine protease falcipain-2, which is essential for parasite growth.
The O-antigen of Plesiomonas shigelloides serotype O36 containing pseudaminic acid
2016
The structure of the repeating unit of O-antigen of Plesiomonas shigelloides serotype O36 has been investigated by 1H and 13C NMR spectroscopy, matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry and chemical methods. The new structure of trisaccharide has been established: →4)-β-Pse5Ac7(R3Hb)-(2 → 4)-β-D-Galp-(1 → 3)-β-D-GlcpNAc-(1→ These trisaccharide O-antigen units substitute the core undecasaccharide at C-4 of the β-D-GlcpNAc residue. The core oligosaccharide and lipid A are identical with these of the serotype O17 (PCM 2231) (Maciejewska, A., Lukasiewicz, J., Kaszowska, M., Jachymek, W., Man-Kupisinska, A.; Lugowski, C. Mar. Drugs.2013, 11 (2), 440–454; Lukasi…
Chemical characterization of a variety of cold-pressed gourmet oils available on the Brazilian market
2018
Different specialty extra virgin oils, produced by cold-pressing fruits/nuts (olive, pequi, palm, avocado, coconut, macadamia and Brazil nut) and seeds (grapeseed and canola), and retailed in the Brazilian region of Minas Gerais, were chemically characterized. Specifically, for each type of oil, the fatty acid composition was elucidated by GC-FID, the contents of selected polyphenols and squalene were determined respectively by UHPLC-MS and UHPLC-PDA, whereas minerals were explored by means of ICP-MS. Olive oil was confirmed to have the highest MUFA content due to a valuable level of oleic acid, while oils from grapeseed, Brazil nut and canola were marked by nutritionally important PUFA lev…
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…
Influence of pitanga leaf extracts on lipid and protein oxidation of pork burger during shelf-life
2018
Abstract The effect of pitanga leaf extracts, as source of natural antioxidants, on physicochemical properties as well as lipid and protein oxidation of pork burgers during storage at 2 ± 1 °C, packed under modified atmosphere, was assessed. Formerly, the in vitro antioxidant and antimicrobial activities as well as the phenolic profile of pitanga leaf extracts were also studied. Thereafter, five samples were prepared, including control (without antioxidants), commercial synthetic antioxidant (BHT at 200 mg/kg) and three concentrations of pitanga leaf extracts: PLL (at 250 mg/kg), PLM (at 500 mg/kg) and PLH (at 1000 mg/kg). The predominant phenolic compounds identified in pitanga leaf extrac…
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…
Variance component analysis to assess protein quantification in biomarker discovery. Application to MALDI-TOF mass spectrometry.
2017
International audience; Controlling the technological variability on an analytical chain is critical for biomarker discovery. The sources of technological variability should be modeled, which calls for specific experimental design, signal processing, and statistical analysis. Furthermore, with unbalanced data, the various components of variability cannot be estimated with the sequential or adjusted sums of squares of usual software programs. We propose a novel approach to variance component analysis with application to the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) technology and use this approach for protein quantification by a classical signal processing algori…
Colletotrin: a sesquiterpene lactone from the endophytic fungus Colletotrichum gloeosporioides associated with Trichilia monadelpha
2017
Abstract A new sesquiterpene lactone, namely colletotrin (1), together with two known fungal metabolites (2, 3), was obtained from a rice culture of Colletotrichum gloeosporioides, an endophytic fungus isolated from the stem bark of Cameroonian medicinal plant Trichilia monadelpha (Meliaceae). The structure of the new compound was established on the basis of extensive NMR analysis (1H, 13C, heteronuclear single-quantum coherence and heteronuclear multiple-bond correlation) completed by high-resolution electrospray ionization mass spectroscopy results and by comparison of these data with those of related compounds described in the literature. Their cytotoxic and antibacterial activities agai…