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101.
Rocío García-Villalba Alegría Carrasco-Pancorbo Ekaterina Nevedomskaya Oleg A. Mayboroda André M. Deelder Antonio Segura-Carretero Alberto Fernández-Gutiérrez 《Analytical and bioanalytical chemistry》2010,398(1):463-475
Olive oil polyphenols have important biological properties which closely depend on their bioavailability; it is, therefore,
essential to understand how polyphenols are absorbed, metabolized, and eliminated from the body. An analytical method based
on rapid-resolution liquid chromatography (RRLC) coupled with mass spectrometric detection with a time-of-flight analyzer
(RRLC–ESI-TOF MS) has been developed for analysis of the main olive oil phenolic compounds and their metabolites in human
urine. Urine samples from ten healthy volunteers were collected before and 2, 4, and 6 h after intake of 50 mL extra-virgin
olive oil. The proposed method includes liquid–liquid extraction with ethyl acetate, which provides extraction recoveries
of the phenolic compounds studied between 35 and 75% from spiked urine samples. Good repeatability was obtained—the relative
standard deviations (RSDs) of peak areas in intra-day and inter-day studies were 4.3 and 6.5%, respectively. Statistical studies
enabled us to discriminate between urine samples before and after intake, and facilitated the search for m/z values enabling this discrimination. Based on the very accurate mass information and the isotopic pattern provided by the
TOF MS analyzer, together with other available information, ten of these biomarkers and more than 50 metabolites, obtained
through phase I and phase II biotransformation reactions, were tentatively identified. Additionally, kinetic studies were
conducted on the metabolites identified as possible biomarkers; for most of the compounds concentrations were maximum in the
first two hours. 相似文献
102.
Oleg L. Tok Kamil Lang Ale Ri
ka Josef Cva
ka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1668-1672
Despite the apparent diversity of the protocols developed for the synthesis of helicenes, they essentially follow the same strategy: the closure of one, or several, internal rings in a key step. Herein, we report the synthesis of a new family of the heterohelicenes consisting of fused silacyclopentadiene rings formed via a facile and novel process. The treatment of oligo(alkynilydenesilylene) precursors of type H2C=CH?(SiMe2?C≡C)n?R (n=3–7), bearing a vinyl group on the terminal silicon atom, with 9‐borabicyclononane leads first to 1,2‐hydroboration of the terminal double bond which then continues with a cascade of intramolecular 1,1‐carboboration reactions accompanied with the closure of a new silole ring after each step affording the target silahelicenes with, currently, up to seven condensed silole rings and with excellent yields. According XRD analysis, the seven fused silole rings of the heptacyclic compound 11 b form an almost complete turn of a helix. The presented one‐pot sequence of reactions is the first example of ring‐by‐ring knitting of a helical framework starting from easily available linear precursors. 相似文献
103.
Oleg Tkachenko Abdur Rahim Andrey Baraban Ruslan Sukhov Inna Khristenko Yoshitaka Gushikem Yuriy Kholin 《Journal of Sol-Gel Science and Technology》2013,66(1):145-154
A sol–gel based hybrid process was developed by manipulating different techniques in sol–gel process to synthesize γ-alumina and (CuO, CuO + ZnO) doped γ-alumina spherical particles. Catalysts having spherical geometry have an important advantage over powders or pellets which are impervious to fluids, when packed in a reactor. Boehmite sol was used as alumina precursor for synthesizing porous γ-alumina and doped materials. γ-alumina particles having 5 wt% CuO, 4 wt% CuO + 1 wt% ZnO, 3 wt% CuO + 2 wt% ZnO and 2 wt% CuO + 3 wt% ZnO were prepared by adding required amounts of Cu(NO3)2 and Zn(NO3)2 solutions prior to gelation of the sol. Methanol dehydration studies were carried out by employing these synthesized catalysts. Hundred percent conversion of methanol to dimethyl ether was observed with (4 wt% CuO + 1 wt% ZnO)-γ-alumina and (5 wt% CuO)-γ-alumina microspheres at 325 and 350 °C, respectively. 相似文献
104.
Oleg S. Radchenko Elena N. Sigida Nadezhda N. Balaneva Pavel S. Dmitrenok Vyacheslav L. Novikov 《Journal of heterocyclic chemistry》2011,48(1):209-214
Unusual course of the reaction was revealed on the oxidation of functionally substituted acridine containing the activated methyl groups by well‐known oxidants, such as selenous acid and selenium(IV) oxide. Treatment of 2‐methoxy‐4,9‐dimethyl‐1‐nitroacridine ( 5 ) with an excess of H2SeO3 in boiling ethanol gave a mixture of the normal reaction products, 2‐methoxy‐4‐methyl‐1‐nitro‐9‐formylacridine ( 11 ) (isolated yield 29%) and 2‐methoxy‐4‐methyl‐1‐nitroacridine‐9‐carboxylic acid ( 12 ) (36%), together with an abnormal product, 3‐methoxy‐5‐methyl‐1H‐selenopheno[2,3,4‐k,l]acridine‐1‐one ( 13 ) (21%), which is the first example of a new seleno‐containing ring system. With the use of SeO2 the yield of selenolactone 13 was much lower. J. Heterocyclic Chem., 2011. 相似文献
105.
Ekaterina V. Pokochueva Dr. Dudari B. Burueva Dr. Oleg G. Salnikov Prof. Igor V. Koptyug 《Chemphyschem》2021,22(14):1421-1440
Parahydrogen-induced polarization with heterogeneous catalysts (HET-PHIP) has been a subject of extensive research in the last decade since its first observation in 2007. While NMR signal enhancements obtained with such catalysts are currently below those achieved with transition metal complexes in homogeneous hydrogenations in solution, this relatively new field demonstrates major prospects for a broad range of advanced fundamental and practical applications, from providing catalyst-free hyperpolarized fluids for biomedical magnetic resonance imaging (MRI) to exploring mechanisms of industrially important heterogeneous catalytic processes. This review covers the evolution of the heterogeneous catalysts used for PHIP observation, from metal complexes immobilized on solid supports to bulk metals and single-atom catalysts and discusses the general visions for maximizing the obtained NMR signal enhancements using HET-PHIP. Various practical applications of HET-PHIP, both for catalytic studies and for potential production of hyperpolarized contrast agents for MRI, are described. 相似文献
106.
Stíbr B Holub J Bakardjiev M Pavlík I Tok OL Císarová I Wrackmeyer B Herberhold M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(10):2239-2244
The reaction of nido-[7,8,9-PC(2)B(8)H(11)] (1) with [[CpFe(CO)(2)](2)] (Cp=eta(5)-C(5)H(5) (-)) in benzene (reflux, 3 days) gave an eta(1)-bonded complex [7-Fp-(eta(1)-nido-7,8,9,-PC(2)B(8)H(10))] (2; Fp=CpFe(CO)(2); yield 38 %). A similar reaction at elevated temperatures (xylene, reflux 24 h) gave the isomeric complex [7-Fp-(eta(1)-nido-7,9,10-PC(2)B(8)H(10))] (3; yield 28 %) together with the fully sandwiched complexes [1-Cp-closo-1,2,4,5-FePC(2)B(8)H(10)] 4 a (yield 30%) and [1-Cp-closo-1,2,4,8-FePC(2)B(8)H(10)] 4 b (yield 5%). Compounds 2 and 3 are isolable intermediates along the full eta(5)-complexation pathway of the phosphadicarbaborane cage; their heating (xylene, reflux, 24 h) leads finally to the isolation of compounds 4 a (yields 46 and 52%, respectively) and 4 b (yields 4 and 5%, respectively). Moreover, compound 3 is isolated as a side product from the heating of 2 (yield 10%). The structure of compound 4 a was determined by an X-ray structural analysis and the constitution of all compounds is consistent with the results of mass spectrometry and IR spectroscopy. Multinuclear ((1)H, (11)B, (31)P, and (13)C), two-dimensional [(11)B-(11)B]-COSY, and (1)H[(11)B(selective)] magnetic resonance measurements led to complete assignments of all resonances and are in excellent agreement with the structures proposed. 相似文献
107.
Harris GJ Polyansky OL Tennyson J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2002,58(4):673-690
We have calculated an ab initio HCN/HNC linelist for all transitions up to J= 25 and 18000 cm(-1) above the zero point energy. This linelist contains more than 200 million lines each with frequencies and transition dipoles. The linelist has been calculated using our semi-global HCN/HNC VQZANO + PES and dipole moment surface, which were reported in van Mourik et al. (J. Chem. Phys. 115 (2001) 3706). With this linelist we synthesise absorption spectra of HCN and HNC at 298 K and we present the band centre and band transition dipoles for the bands which are major features in these spectra. Several of the HCN bands and many of the HNC bands have not been previously studied. Our line intensities reproduce via fully ab initio methods the unusual intensity structure of the HCN CN stretch fundamental (00(0)1) for the first time and also the forbidden (02(2)0) HCN bending overtone. We also compare the J = 1-->0 pure rotational transition dipole in the HCN/HNC ground and vibrationally excited states with experimental and existing ab initio results. 相似文献
108.
109.
Kosyakov Dmitry S. Anikeenko Elena A. Ul’yanovskii Nikolay V. Khoroshev Oleg Yu Shavrina Irina S. Gorbova Natalya S. 《Analytical and bioanalytical chemistry》2018,410(28):7429-7439
Analytical and Bioanalytical Chemistry - The use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the study of lignin is still extremely limited due to its low... 相似文献
110.