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41.
Partial least squares model and design of experiments toward the analysis of the metabolome of Jatropha gossypifolia leaves: Extraction and chromatographic fingerprint optimization 下载免费PDF全文
Fausto Carnevale Neto Rafael Teixeira Freire Patrícia Cardoso Renato Lajarim Carneiro Vanderlan Da Silva Bolzani Ian Castro‐Gamboa 《Journal of separation science》2016,39(6):1023-1030
A major challenge in metabolomic studies is how to extract and analyze an entire metabolome. So far, no single method was able to clearly complete this task in an efficient and reproducible way. In this work we proposed a sequential strategy for the extraction and chromatographic separation of metabolites from leaves Jatropha gossypifolia using a design of experiments and partial least square model. The effect of 14 different solvents on extraction process was evaluated and an optimized separation condition on liquid chromatography was estimated considering mobile phase composition and analysis time. The initial conditions of extraction using methanol and separation in 30 min between 5 and 100% water/methanol (1:1 v/v) with 0.1% of acetic acid, 20 μL sample volume, 3.0 mL min?1 flow rate and 25°C column temperature led to 107 chromatographic peaks. After the optimization strategy using i‐propanol/chloroform (1:1 v/v) for extraction, linear gradient elution of 60 min between 5 and 100% water/(acetonitrile/methanol 68:32 v/v with 0.1% of acetic acid), 30 μL sample volume, 2.0 mL min?1 flow rate, and 30°C column temperature, we detected 140 chromatographic peaks, 30.84% more peaks compared to initial method. This is a reliable strategy using a limited number of experiments for metabolomics protocols. 相似文献
42.
Elisabetta Coppi Federica Cherchi Martina Venturini Elena Lucarini Renato Corradetti Lorenzo Di Cesare Mannelli Carla Ghelardini Felicita Pedata Anna Maria Pugliese 《Molecules (Basel, Switzerland)》2022,27(6)
Ligands of the Gi protein-coupled adenosine A3 receptor (A3R) are receiving increasing interest as attractive therapeutic tools for the treatment of a number of pathological conditions of the central and peripheral nervous systems (CNS and PNS, respectively). Their safe pharmacological profiles emerging from clinical trials on different pathologies (e.g., rheumatoid arthritis, psoriasis and fatty liver diseases) confer a realistic translational potential to these compounds, thus encouraging the investigation of highly selective agonists and antagonists of A3R. The present review summarizes information on the effect of latest-generation A3R ligands, not yet available in commerce, obtained by using different in vitro and in vivo models of various PNS- or CNS-related disorders. This review places particular focus on brain ischemia insults and colitis, where the prototypical A3R agonist, Cl-IB-MECA, and antagonist, MRS1523, have been used in research studies as reference compounds to explore the effects of latest-generation ligands on this receptor. The advantages and weaknesses of these compounds in terms of therapeutic potential are discussed. 相似文献
43.
In this work, the complexes formed between formamide and water were studied by means of the SAPT and AIM methods. Complexation leads to significant alterations in the geometries and electronic structure of formamide. Intermolecular interactions in the complexes are intense, especially in the cases where the solvent interacts with the carbonyl and amide groups simultaneously. In the transition states, the interaction between the water molecule and the lone pair on the amide nitrogen is also important. In all the complexes studied herein, the electrostatic interactions between formamide and water are the main attractive force, and their contribution may be five times as large as the corresponding contribution from dispersion, and twice as large as the contribution from induction. However, an increase in the resonance of planar formamide with the successive addition of water molecules may suggest that the hydrogen bonds taking place between formamide and water have some covalent character. 相似文献
44.
Rosseto R Bibak N DeOcampo R Shah T Gabrielian A Hajdu J 《The Journal of organic chemistry》2007,72(5):1691-1698
A new stereoselective synthesis of lysophosphatidylcholines is reported. The synthesis is based upon (1) the use of 3-p-toluenesulfonyl-sn-glycerol to provide the stereocenter for construction of the optically active lysophospholipid molecule, (2) tetrahydropyranylation of the secondary alcohol function to achieve orthogonal protection of the sn-2- and sn-3-glycerol positions, and (3) elaboration of the phosphodiester headgroup using a 2-chloro-1,3,2-dioxaphospholane/trimethylamine sequence. In the course of developing the synthesis it has been discovered that methoxyacetate displacement of the sn-3-p-toluenesulfonate yields a reactive methoxyacetyl ester, which in turn can be selectively cleaved with methanol/tert-butylamine, while the ester group at the sn-1-position remains unaffected. The sequence has been shown to be suitable for preparation of spectroscopically labeled lysophosphatidylcholines. One of these compounds was readily converted to a double-labeled mixed-chain phosphatidylcholine applicable for real-time fluorescence resonance energy transfer (FRET) assay of lipolytic enzymes. In addition, the work led to new synthetic strategies based on chemoselective manipulation of the tosyl group in the presence of other base-labile groups such as FMOC derivatives that are often used for the protection of amino and hydroxyl groups in syntheses. 相似文献
45.
Tessore F Roberto D Ugo R Pizzotti M Quici S Cavazzini M Bruni S De Angelis F 《Inorganic chemistry》2005,44(24):8967-8978
Coordination of 4'-(C6H4-p-X)-2,2':6',2'-terpyridines [X = NO2, NBu2, (E)-CH=CH-C6H4-p-NBu2, (E,E)-(CH=CH)2-C6H4-p-NMe2] to Zn(II), Ru(III), and Ir(III) metal centers induces a significant enhancement of the absolute value of the second-order nonlinear optical (NLO) response of the terpyridine, measured by means of both electric field induced second harmonic generation and solvatochromic methods. By varying the nature of the metal center, the enhanced second-order NLO response shifts from positive to negative. Such a shift is controlled by electronic charge-transfer transitions, such as metal-to-ligand or ligand-to-metal transitions, in addition to the intraligand charge transfer. The enhancement generated by coordination is also controlled by the chelation effect and by fine-tuning of the ancillary ligands. 相似文献
46.
Study of a Novel Bisnaphthalimidopropyl Polyamine as Electroactive Material for Perchlorate‐selective Potentiometric Sensors 下载免费PDF全文
Renato Gil Célia G. Amorim Laura Crombie Paul Kong Thoo Lin Alberto Araújo Maria da Conceição Montenegro 《Electroanalysis》2015,27(12):2809-2819
In this work, the new polyamine bisnaphthalimidopropyl‐4,4’‐diaminodiphenylmethane is proposed as a new ionophore for perchlorate potentiometric sensors. The optimal formulation for the membrane comprised of 12 mmol kg?1 of the ionophore, and 68 % (w/w) of 2‐nitrophenyl phenyl ether as plasticizer and 31 % (w/w) of high molecular weight PVC. The sensors were soaked in water for a week to allow leakage of anionic impurities and for one day in a perchlorate solution (10?4 mol L?1) to improve reproducibility due to its first usage. The stability constant for the ionophore‐perchlorate association in the membrane, log βIL1=3.18±0.04, ensured a performance characterized by the slope of 54.1 (±0.7) mV dec?1 to perchlorate solutions with concentrations between 1.24×10?7 and 1.00×10?3 mol L?1. The sensors are insensitive to pH between 3.5 to 11.0, they have a practical detection limit of 7.66 (±0.42) ×10?8 mol L?1 and a response time below 60 s for solutions with perchlorate concentrations above 5×10?6 mol L?1. The accuracy of the results was confirmed by the analysis of the contaminant in a certified reference water sample. 相似文献
47.
Oliveira FC Effenberger FB Sousa MH Jardim RF Kiyohara PK Dupont J Rubim JC Rossi LM 《Physical chemistry chemical physics : PCCP》2011,13(30):13558-13564
This work describes an easy synthesis (one pot) of MFe(2)O(4) (M = Co, Fe, Mn, and Ni) magnetic nanoparticles MNPs by the thermal decomposition of Fe(Acac)(3)/M(Acac)(2) by using BMI·NTf(2) (1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) or BMI·PF(6) (1-n-butyl-3-methylimidazolium hexafluorophosphate) ionic liquids (ILs) as recycling solvents and oleylamine as the reducing and surface modifier agent. The effects of reaction temperature and reaction time on the features of the magnetic nanomaterials (size and magnetic properties) were investigated. The growth of the MNPs is easily controlled in the IL by adjusting the reaction temperature and time, as inferred from Fe(3)O(4) MNPs obtained at 150 °C, 200 °C and 250 °C with mean diameters of 8, 10 and 15 nm, respectively. However, the thermal decomposition of Fe(Acac)(3) performed in a conventional high boiling point solvent (diphenyl ether, bp 259 °C), under a similar Fe to oleylamine molar ratio used in the IL synthesis, does not follow the same growth mechanism and rendered only smaller NPs of 5 nm mean diameter. All MNPs are covered by at least one monolayer of oleylamine making them readily dispersible in non-polar solvents. Besides the influence on the nanoparticles growth, which is important for the preparation of highly crystalline MNPs, the IL was easily recycled and has been used in at least 20 successive syntheses. 相似文献
48.
Katharina Root Yves Wittwer Konstantin Barylyuk Ulrike Anders Renato Zenobi 《Journal of the American Society for Mass Spectrometry》2017,28(9):1863-1875
Native ESI-MS is increasingly used for quantitative analysis of biomolecular interactions. In such analyses, peak intensity ratios measured in mass spectra are treated as abundance ratios of the respective molecules in solution. While signal intensities of similar-size analytes, such as a protein and its complex with a small molecule, can be directly compared, significant distortions of the peak ratio due to unequal signal response of analytes impede the application of this approach for large oligomeric biomolecular complexes. We use a model system based on concatenated maltose binding protein units (MBPn, n = 1, 2, 3) to systematically study the behavior of protein mixtures in ESI-MS. The MBP concatamers differ from each other only by their mass while the chemical composition and other properties remain identical. We used native ESI-MS to analyze model mixtures of MBP oligomers, including equimolar mixtures of two proteins, as well as binary mixtures containing different fractions of the individual components. Pronounced deviation from a linear dependence of the signal intensity with concentration was observed for all binary mixtures investigated. While equimolar mixtures showed linear signal dependence at low concentrations, distinct ion suppression was observed above 20 μM. We systematically studied factors that are most often used in the literature to explain the origin of suppression effects. Implications of this effect for quantifying protein–protein binding affinity by native ESI-MS are discussed in general and demonstrated for an example of an anti-MBP antibody with its ligand, MBP. 相似文献
49.
Recently, a new and efficient method for total homocysteine (tHcy) quantitation in plasma using trap and release membrane introduction mass spectrometry (T&R-MIMS) with a versatile removable direct introduction membrane probe (DIMP) was described [R. Haddad, M. A. Mendes, N. F. Hoehr and M. N. Eberlin, Analyst, 2001, 126, 1212]. Herein we report on the use of the DIMP-T&R-MIMS technique for total cysteine (tCys) quantitation; hence combined tCys and tHcy quantitation in plasma or serum can be achieved. The method employs Cys and Hcy derivatization with ethyl chloroformate (after disulfide bond reduction with dithiothreitol and protein precipitation with trichloroacetic acid), preconcentration in a capillary silicone membrane, and their thermal desorption to the gas phase inside the ion source region of a mass spectrometer, at a point exactly between the two ionization filaments. Thermal desorption uses the uniform heat radiation provided by the two ionization filaments. The analytes are then ionized by electron ionization and both Cys and Hcy are quantitated by mass spectrometry using selected ion monitoring. For tCys quantitation, good linearity and reproducibility was observed for concentrations ranging from 5 to 350 microM, recovery was near 95%, and the limit of detection (LOD) was of 2 microM. This LOD is well below the mean Cys concentration in plasma, and serum samples from a large group of healthy people showed a mean tCys concentration of 132 +/- 45 microM. 相似文献
50.
Renato S. Gonnelli Mauro Tortello Dario Daghero Giovanni Alberto Ummarino Valeri A. Stepanov Jun S. Kim 《Central European Journal of Physics》2009,7(2):251-256
Point-contact Andreev-reflection (PCAR) experiments were performed in the Fe-1111 layered superconductor LaFeAsO0.9F0.1 with resistive T
c
on
∼ 27 K. The observation of two pairs of peaks in the low-temperature Andreev-reflection spectra clearly indicates the presence
of two order parameters. The behavior of the two gaps as a function of temperature, obtained by fitting the conductance curves
by means of the generalized two-band Blonder-Tinkham-Klapwijk model, shows some anomalies. A theoretical analysis performed
within the two-band Eliashberg theory with a generic electron-boson coupling can reproduce the low-temperature value of the
two gaps but generally fails in giving a satisfactory fit of their overall temperature dependence, indicating the rich and
complex physics of these newly discovered superconductors.
相似文献