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排序方式: 共有675条查询结果,搜索用时 281 毫秒
31.
Aldo Laganà Angelo Faberi Giovanna Fago Aldo Marino Elisabetta Pastorini Roberto Samperi 《International journal of environmental analytical chemistry》2013,93(13):1009-1016
The metabolic fate of the estrogenic mycotoxin zearalenone in rainbow trout is presently unknown. In this study, the tissue concentration of zearalenone and its principal metabolites (α-zearalenol and β-zearalenol) was determined. A known amount of zearalenone was administered as a single bolus to ten fish, and the biological tissue concentration was determined at various times following administration. The analytes were extracted from liver and muscular tissue using an on-line matrix solid-phase dispersion–solid-phase extraction sample preparation protocol, and their concentration determined by HPLC–Turboionspray–tandem mass spectrometry. The results showed that zearalenone is mainly metabolized into α-zearalenol in both liver and muscular tissues. The maximum concentrations of each analyte found in liver were 76.1, 211.2 and 63.7?ng/g respectively for zearalenone, α-zearalenol and β-zearalenol, while in muscular tissue they were 10.7, 8.2 and 6.5?ng/g. These values were reached after 2?h in liver tissue and 12?h in muscular tissue. Moreover the data obtained showed that the elimination rate in liver is quite fast since 48?h after the exposure less than 7% of the maximum concentration found is still present. In muscular tissue, however, about one-third of the maximum concentration found is still present after 48?h. 相似文献
32.
Dr. Francesco Rigodanza Prof. Nadia Marino Dr. Alessandro Bonetto Prof. Antonio Marcomini Prof. Marcella Bonchio Prof. Mirco Natali Prof. Andrea Sartorel 《Chemphyschem》2021,22(12):1208-1218
The cobalt substituted polyoxotungstate [Co6(H2O)2(α-B-PW9O34)2(PW6O26)]17− ( Co6 ) displays fast electron transfer (ET) kinetics to photogenerated RuIII(bpy)33+, 4 to 5 orders of magnitude faster than the corresponding ET observed for cobalt oxide nanoparticles. Mechanistic evidence has been acquired indicating that: (i) the one-electron oxidation of Co6 involves Co(II) aquo or Co(II) hydroxo groups (abbreviated as Co6(II) −OH 2 and Co6(II) −OH, respectively, whose speciation in aqueous solution is associated to a pKa of 7.6), and generates a Co(III)−OH moiety ( Co6(III) −OH), as proven by transient absorption spectroscopy; (ii) at pH>pKa, the Co6(II) −OH→RuIII(bpy)33+ ET occurs via bimolecular kinetics, with a rate constant k close to the diffusion limit and dependent on the ionic strength of the medium, consistent with reaction between charged species; (iii) at pH <pKa, the process involves Co6(II) − OH2 → Co6(III)−OH transformation and proceeds via a multiple-site, concerted proton electron transfer (CPET) where water assists the transfer of the proton, as proven by the absence of effect of buffer base concentrations on the rate of the ET and by a H/D kinetic isotope in a range of 1.2–1.4. The reactivity of water is ascribed to its organization on the surface of the polyanionic scaffold through hydrogen bond networking involving the Co(II)−OH2 group. 相似文献
33.
Luana Malacaria Giuseppina Anna Corrente Amerigo Beneduci Emilia Furia Tiziana Marino Gloria Mazzone 《Molecules (Basel, Switzerland)》2021,26(9)
This review focuses on the ability of some natural antioxidant molecules (i.e., hydroxycinnamic acids, coumarin-3-carboxylic acid, quercetin, luteolin and curcumin) to form Al(III)- and Fe(III)-complexes with the aim of evaluating the coordination properties from a combined experimental and theoretical point of view. Despite the contributions of previous studies on the chemical properties and biological activity of these metal complexes involving such natural antioxidants, further detailed relationships between the structure and properties are still required. In this context, the investigation on the coordination properties of Al(III) and Fe(III) toward these natural antioxidant molecules might deserve high interest to design water soluble molecule-based metal carriers that can improve the metal’s intake and/or its removal in living organisms. 相似文献
34.
Dr. Wawrzyniec Kaszub Andrea Marino Dr. Maciej Lorenc Prof. Eric Collet Prof. Elena G. Bagryanskaya Prof. Evgeny V. Tretyakov Prof. Victor I. Ovcharenko Prof. Matvey V. Fedin 《Angewandte Chemie (International ed. in English)》2014,53(40):10636-10640
Molecular compounds with photoswitchable magnetic properties have been intensively investigated over the last decades due to their prospective applications in nanoelectronics, sensing and magnetic data storage. The family of copper‐nitroxide‐based molecular magnets represents a new promising type of photoswitchable compounds. We report the first study of these appealing systems using femtosecond optical spectroscopy. We unveil the mechanism of ultrafast (<50 fs) spin state photoswitching and establish its principal differences compared to other photoswitchable magnets. On this basis, we propose potential advantages of copper‐nitroxide‐based molecular magnets for the future design of ultrafast magnetic materials. 相似文献
35.
Inga Kwiecie Natalizia Miceli Manuela DArrigo Andreana Marino Halina Ekiert 《Molecules (Basel, Switzerland)》2022,27(3)
Studies carried out using three different in vitro assays and a biological setting (Escherichia coil) demonstrated the antioxidant activity of Scutellaria lateriflora microshoot extract. Moreover, the extract exhibited no toxicity in a brine shrimp lethality bioassay. These results indicated that microshoots are a rich, safe source of antioxidants, which encouraged us to enhance their production in vitro. In agar and agitated cultures, two biotechnological strategies were applied: feeding the cultures with the biogenetic precursors of the phenolics—phenylalanine and tyrosine, and eliciting them with methyl jasmonate. Specific Scutellaria flavonoids and verbascoside were analysed by HPLC. Feeding with precursors (1 g/L) in agar cultures decreased the production of the metabolites. In agitated cultures, different concentrations of precursors (1.0–2.5 g/L) and the elicitor (10; 50; 100 µM) were tested. Additionally, parallel feeding with the precursor and elicitor in a concentration of 50 µM were applied. The best strategy for total flavonoid and verbascoside production was phenylalanine feeding (1.5 g/L), max. 3765 and 475 mg/100 g DW, respectively, after 7 days. This is the first report documenting the high antioxidant production in S. lateriflora microshoots after feeding with phenylalanine. Moreover, for the first time, bioreactor cultures were successfully maintained, obtaining attractive results (max. total flavonoid content 2348 and verbascoside 485 mg/100 g DW). 相似文献
36.
The thermal degradation behaviour, in the absence of oxygen, of poly(p-methylstyrene) has been investigated. Monomer is the main product formed in the degradation process, together with different oligomers which have been identified and whose amounts have been determined. A reaction mechanism accounting for the formation of the degradation products, and similar to the mechanism established for polystyrene, is proposed. The main differences of the process comparing with polystyrene are the higher amount of monomer which is produced and the crosslinking structures which are formed at T < 400° C. 相似文献
37.
Dr. Steve Y. Rhieu Dr. Aaron A. Urbas Dr. Daniel W. Bearden Dr. John P. Marino Dr. Katrice A. Lippa Dr. Vytas Reipa 《Angewandte Chemie (International ed. in English)》2014,53(2):447-450
Non‐invasive and real‐time analysis of cellular redox processes has been greatly hampered by lack of suitable measurement techniques. Here we describe an in‐cell nuclear magnetic resonance (NMR) based method for measuring the intracellular glutathione redox potential by direct and quantitative measurement of isotopically labeled glutathione introduced exogenously into living yeast. By using this approach, perturbations in the cellular glutathione redox homeostasis were also monitored as yeast cells were subjected to oxidative stress. 相似文献
38.
Summary A multiresidue method has been developed for identification and quantitation of the herbicides most commonly used in cultivation
of maize and grain, and of their transformation products, in soil samples. The analytes were isolated by soil column extraction
(SCE) and the extracts were purified by use of a Carbograph-1 cartridge. Analysis was performed by liquid chromatography coupled
with tandem mass spectrometric detection (LC-TISP-MS-MS) in negative-ion mode. To optimize the extraction conditions affecting
the performance of SCE, e.g. the extracting solvent used, temperature, extracting volume, and solvent flow rate, were studied.
To evaluate the matrix effect in SCE, recovery experiments were performed on soil samples, with different physical and chemical
characteristics, fortified with the 100 ng g−1 of the target compounds. Recovery data were satisfactory and the method detection limits were between 3 and 100 ng g−1, depending on the compound. 相似文献
39.
Carmen FestaSimona De Marino Valentina SepeMaria Valeria D’Auria Giuseppe BifulcoRosa Andrés Maria Carmen TerencioMiguel Payá Cécile DebitusAngela Zampella 《Tetrahedron》2011,67(40):7780-7786
Two new cyclopeptides, perthamides E and F were isolated from the polar extracts of the sponge Theonella swinhoei. The new structures, featuring an unprecedented β-amino acid unit (AHMOA), were determined by interpretation of NMR and MS data. The absolute configuration of the AHMOA residue was proposed on the basis of quantum chemical calculation of NMR chemical shifts. Perthamides were proved to inhibit TNF-α and IL-8 release in primary human keratinocytes cells and therefore could represent potentially leads for the treatment of psoriasis. 相似文献
40.
DellErba C Gasparrini F Grilli S Lunazzi L Mazzanti A Novi M Pierini M Tavani C Villani C 《The Journal of organic chemistry》2002,67(5):1663-1668
Static and dynamic stereochemistry of the hydrocarbon comprising a phenyl ring bearing two alpha-naphthyl substituents in the ortho positions, i.e., 1,2-di-(4-methyl-naphth-1-yl)-benzene 1, has been studied by a combination of variable temperature NMR, cryogenic HPLC, and MM calculations. Whereas in solution both syn (meso) and anti (chiral) forms were observed and the corresponding interconversion barrier was determined (Delta G(++) = 19.5 kcal mol(-1)), only the diastereoisomer anti was found to be present in the crystalline state (X-ray diffraction). When the molecule is rendered asymmetric by introduction of a nitro group in the phenyl ring as in 1,2-di-(4-methyl-naphth-1-yl)-4-nitrobenzene 2, the chiral syn and anti diastereoisomers are simultaneously present both in solution and in the solid state, albeit in different proportions. Cryogenic chromatography on a HPLC chiral stationary phase at 20 degrees C allowed the stereolabile diastereoisomers and the corresponding enantiomers to be separated. 相似文献