共查询到20条相似文献,搜索用时 31 毫秒
1.
Yehua Jin Chien‐Hung Yeh Christian A. Kuttruff Lars Jrgensen Georg Dünstl Jakob Felding Swaminathan R. Natarajan Phil S. Baran 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(47):14250-14254
Ingenol derivatives with varying degrees of oxidation were prepared by two‐phase terpene synthesis. This strategy has allowed access to analogues that cannot be prepared by semisynthesis from natural ingenol. Complex ingenanes resulting from divergent C H oxidation of a common intermediate were found to interact with protein kinase C in a manner that correlates well with the oxidation state of the ingenane core. Even though previous work on ingenanes has suggested a strong correlation between potential to activate PKCδ and induction of neutrophil oxidative burst, the current study shows that the potential to activate PKCβII is of key importance while interaction with PKCδ is dispensable. Thus, key modifications of the ingenane core allowed PKC isoform selectivity wherein PKCδ‐driven activation of keratinocytes is strongly reduced or even absent while PKCβII‐driven activation of neutrophils is retained. 相似文献
2.
New bis[N‐(2,6‐di‐tert‐butyl‐1‐hydroxyphenyl)salicylideneminato]copper(II) complexes bearing HO and CH3O substituents on the salicyaldehyde moiety were prepared, and have been characterized by elemental analyses, IR, UV/Vis, ESR spectroscopy, and magnetic moments. It has been found that in the synthesis of CH3O substituted complexes unlike HO bearing, the oxidative C–C coupling of coordinated salicylaldimine ligands take place. It has been suggested that the intermolecular H‐bonding is a dominant factor in controlling of oxidative C–C coupling conversion. The powder ESR spectra of CH3O substituted compounds unlike of HO are typical of a triplet state CuII dimers with a half‐field forbidden (δM = ± 2) and the allowed (δM = ± 1) transitions at 300 and 113 K. 相似文献
3.
Molecular modeling of interactions of four 7- or 8-substituted benzolactam-V8 (BLV) molecules with the cys2 activator-binding domain of protein kinase C (PKCδ) was carried out using molecular docking program Autodock. The docked models reveal that the hydroxymethyl group at the C(5) atom of the eight-membered ring of each BLV is bound at the bottom of the binding groove of the cys2 domain of PKCδ The BLV molecules make hydrogen bonds and hydrophobic interactions with PKCδ, which are similar to those in the crystal structure of the cys2 domain of PKCδ in complex with phorbol 13-acetate. BLV-1 does not contain a long side chain that is hydrophobic and necessary for membrane insertion, so that it would not be a potent modulator of PKCδ. The other three BLV molecules have long side chains substituted at C(7) or C(8) atoms, and it was predicted, based on the docking results, that they had the PKCδ-binding affinity in the order of BLV-2〉BLV-4〉BLV-3, and BLV-2 would be a potent activator of PKCδ. 相似文献
4.
Guillaume Desmares Delphine Lefebvre Gilles Renevret ClaudeLe Drian 《Helvetica chimica acta》2001,84(4):880-889
Alternative conditions for the classical glycosidation method of Koenigs‐Knorr allowed us to prepare selectively β‐D ‐glucosides of several hindered alcohols in good yields in a weakly acidic to almost neutral medium. To illustrate the versatility of our conditions, we prepared the β‐D ‐glucoside of an acid‐sensitive aglycone, a key‐intermediate for the total synthesis of a natural cyanoglucoside, bauhinin. 相似文献
5.
In this paper, aliphatic polyesters functionalized with pendant carboxylic groups were synthesized via several steps. Firstly, substituted cyclic ketone, 2‐(benzyloxycarbonyl methyl)cyclopentanone (BCP) was prepared through the reaction of enamine with benzyl‐2‐bromoacetate, and subsequently converted into the relevant functionalized δ‐valerolactone derivative, 5‐(benzyloxy carbonylmethyl)‐δ‐valerolactone (BVL) by the Baeyer‐Villiger oxidation. Secondly, the ring‐opening polymerization of BVL with ε‐caprolactone was carried out in bulk using stannous octoate as the catalyst to produce poly(ε‐caprolactone‐co‐δ‐valerolactone) bearing the benzyl‐protected carboxyl functional groups [P(CL‐co‐BVL)]. Finally, the benzyl‐protecting groups of P(CL‐co‐BVL) were effectively removed by H2 using Pd/C as the catalyst to obtain poly(ε‐caprolactone‐co‐δ‐valerolactone) bearing pendant carboxylic acids [P(CL‐co‐CVL)]. The structure and the properties of the polymer have been studied by Nuclear Magnetic Resonance (NMR), Fourier Infrared Spectroscopy (FT‐IR) and Differential Scan Calorimetry (DSC) etc. The NMR and FT‐IR results confirmed the polymer structure, and the 13C NMR spectra have clearly interpreted the sequence of ε‐caprolactone and 5‐(benzyloxycarbonylmethyl)‐δ‐valerolactone in the copolymer. When the benzyl‐protecting groups were removed, the aliphatic polyesters bearing carboxylic groups were obtained. Moreover, the hydrophilicity of the polymer was improved. Thus, poly(ε‐caprolactone‐co‐δ‐valerolactone) might have great potential in biomedical fields. 相似文献
6.
Shankha S. Acharyya Shilpi Ghosh Yusuke Yoshida Takuma Kaneko Takehiko Sasaki Yasuhiro Iwasawa 《Chemical record (New York, N.Y.)》2019,19(9):2069-2081
Catalytic benzene C?H activation toward selective phenol synthesis with O2 remains a stimulating challenge to be tackled. Phenol is currently produced industrially by the three‐steps cumene process in liquid phase, which is energy‐intensive and not environmentally friendly. Hence, there is a strong demand for an alternative gas‐phase single‐path reaction process. This account documents the pivotal confined single metal ion site platform with a sufficiently large coordination sphere in β zeolite pores, which promotes the unprecedented catalysis for the selective benzene hydroxylation with O2 under coexisting NH3 by the new inter‐ligand concerted mechanism. Among alkali and alkaline‐earth metal ions and transition and precious metal ions, single Cs+ and Rb+ sites with ion diameters >0.300 nm in the β pores exhibited good performances for the direct phenol synthesis in a gas‐phase single‐path reaction process. The single Cs+ and Rb+ sites that possess neither significant Lewis acidic?basic property nor redox property, cannot activate benzene, O2, and NH3, respectively, whereas when they coadsorbed together, the reaction of the inter‐coadsorbates on the single alkali‐metal ion site proceeds concertedly (the inter‐ligand concerted mechanism), bringing about the benzene C?H activation toward phenol synthesis. The NH3‐driven benzene C?H activation with O2 was compared to the switchover of the reaction pathways from the deep oxidation to selective oxidation of benzene by coexisting NH3 on Pt6 metallic cluster/β and Ni4O4 oxide cluster/β. The NH3‐driven selective oxidation mechanism observed with the Cs+/β and Rb+/β differs from the traditional redox catalysis (Mars‐van Krevelen) mechanism, simple Langmuir‐Hinshelwood mechanism, and acid?base catalysis mechanism involving clearly defined interaction modes. The present catalysis concept opens a new way for catalytic selective oxidation processes involving direct phenol synthesis. 相似文献
7.
Dr. Zhijay Tu Hsiao‐Wu Hsieh Chih‐Ming Tsai Chia‐Wei Hsu Dr. Shy‐Guey Wang Kuan‐Jung Wu Prof. Dr. Kuo‐I Lin Prof. Dr. Chun‐Hung Lin 《化学:亚洲杂志》2013,8(7):1536-1550
We have developed an expeditious procedure to yield large amounts of orthogonally protected Gal‐β1,3/4‐GlcNAc, which allowed for the systematic introduction of a sulfate group onto the C3/C6 positions of Gal and/or the C6 position of GlcNAc. In particular, the disaccharide precursors were prepared in five or six steps and high overall yield from para‐tolyl‐6‐O‐tert‐butyldiphenylsilyl‐1‐thio‐β‐D ‐galactopyranoside. After deprotection and sulfation steps, the final products were characterized by using several NMR methods to unambiguously confirm the location of each introduced sulfate group and they were examined for their binding specificity of human galectin‐1 and galectin‐8. 相似文献
8.
Synthesis and NMR Spectroscopic Elucidation of Four Diastereoisomers of Oxygenated Bisabolane Side Chain
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Misaki Hirai Rurina Miyazaki Kana Mitsui Kota Kiuchi Hiroyuki Onuki Hiroshi Hirota Chiaki Kuroda 《Helvetica chimica acta》2015,98(8):1035-1060
Four possible stereoisomers of a model compound of highly O‐bearing bisabolane sesquiterpenes were synthesized and their NMR spectra were compared. Starting from isopulegol, allylic oxidation and Grignard reaction afforded a mixture of alcohols at C(8), which was separated. After metathesis reaction, both α‐ and β‐epoxides were obtained via non‐stereoselective epoxidation, while VO(OiPr)3‐catalyzed epoxidation afforded a single diastereoisomer selectively. NMR Spectra of twelve synthesized compounds, four stereoisomers of acetates, isobutyrates, and tiglates, were measured. A difference between C(8α)‐ and C(8β)‐acyloxy isomers was observed in the δ‐values of H? C(8) in CDCl3. Within the 8β‐acyloxy compounds, the α‐ and the β‐epoxides were distinguished by either the J‐value of H? C(8) or the chemical shift of CH2(9). Within the 8α‐acyloxy compounds, two epoxide isomers were distinguished by the J‐value of H? C(10) in C6D6 or in CD3OD. 相似文献
9.
Binh Thanh Nguyen Min Park Jae‐Chul Pyun Young Sook Yoo Min‐Jung Kang 《Electrophoresis》2016,37(23-24):3146-3153
An assay for protein kinase C delta (PKCδ) activity based on the quantification of a synthetic substrate using capillary electrophoresis with laser‐induced fluorescence detection was developed. The peptides labeled with fluorescein isothiocyanate F‐ERK (where ERK is extracellular signal‐regulated kinase) and the phosphorylated form, P‐F‐ERK, were utilized for the method development and validation. The migration time of F‐ERK and P‐F‐ERK were 6.3 ± 0.1 and 8.7 ± 0.2 min, respectively. LOD and LOQ values of F‐ERK were 2 and 6 ng/mL and those of P‐F‐ERK were 4 and 12 ng/mL. The correlation coefficients obtained from two standard curves were approximately 0.99. The reproducibility and accuracy of the method for F‐ERK ranged 1.5–4.7 and 86–109%, respectively, and those for P‐F‐ERK were 1.6–6.1 and 93–109%, respectively. The activity of PKCδ was studied in vitro using the human gastric cancer cell line MKN‐1. The use of PKCδ inhibitor candidates, including G?6983, bisindolylmaleimide II, staurosporine, and rottlerin in the assay resulted in IC50 values of 50 nM, 15 nM, 795 nM, and 4 μM, respectively. Comparison of our assay with a commercial PKC kit revealed that our assay is more adaptable to differing enzyme isoforms. This method has potential for high throughput screening for kinase inhibitors as part of a drug discovery program. 相似文献
10.
Douglas J. Morrison Karen Cooper Tom Preston 《Rapid communications in mass spectrometry : RCM》2010,24(12):1799-1804
Carbon isotope analysis by bulk elemental analysis coupled with isotope ratio mass spectrometry has been the mainstay of δ13C analyses both at natural abundance and in tracer studies. More recently, compound‐specific isotope analysis (CSIA) has become established, whereby organic constituents are separated online by gas or liquid chromatography before oxidation and analysis of CO2 for constituent δ13C. Theoretically, there should be concordance between bulk δ13C measurements and carbon‐weighted δ13C measurements of carbon‐containing constituents. To test the concordance between the bulk and CSIA, fish oil was chosen because the majority of carbon in fish oil is in the triacylglycerol form and ~95% of this carbon is amenable to CSIA in the form of fatty acids. Bulk isotope analysis was carried out on aliquots of oil extracted from 55 fish samples and δ13C values were obtained. Free fatty acids (FFAs) were produced from the oil samples by saponification and derivatised to fatty acid methyl esters (FAMEs) for CSIA by gas chromatography/combustion/isotope ratio mass spectrometry. A known amount of an internal standard (C15:0 FAME) was added to allow analyte quantitation. This internal standard was also isotopically calibrated in both its FFA (δ13C = ?34.30‰) and FAME (δ13C = ?34.94‰) form. This allowed reporting of FFA δ13C from measured FAME δ13C values. The bulk δ13C was reconstructed from CSIA data based on each FFA δ13C and the relative amount of CO2 produced by each analyte. The measured bulk mean δ13C (SD) was ?23.75‰ (1.57‰) compared with the reconstructed bulk mean δ13C of ?23.76 (1.44‰) from CSIA and was not significantly different. Further analysis of the data by the Bland‐Altman method did not show particular bias in the data relative to the magnitude of the measurement. Good agreement between the methods was observed with the mean difference between methods (range) of 0.01‰ (?1.50 to 1.30). Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
11.
Sumin Lee Natthawat Semakul Tomislav Rovis 《Angewandte Chemie (International ed. in English)》2020,59(12):4965-4969
We report a RhIII‐catalyzed regio‐ and diastereoselective synthesis of δ‐lactams from readily available acrylamide derivatives and unactivated alkenes. The reaction provides a rapid route to a diverse set of δ‐lactams in good yield and stereoselectivity, which serve as useful building blocks for substituted piperidines. The regioselectivity of the reaction with unactivated terminal alkene is significantly improved by using Cpt ligand on the RhIII catalyst. The synthetic utility of the reaction is demonstrated by the preparation of a potential drug candidate containing a trisubstituted piperidine moiety. Mechanistic studies show that the reversibility of the C?H activation depends on the choice of Cp ligand on the RhIII catalyst. The irreversible C?H activation is observed and becomes turnover‐limiting with [CptRhCl2]2 as catalyst. 相似文献
12.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(6):1539-1543
Nanoparticulate gold supported on a Keggin‐type polyoxometalate (POM), Cs4[α‐SiW12O40]⋅n H2O, was prepared by the sol immobilization method. The size of the gold nanoparticles (NPs) was approximately 2 nm, which was almost the same as the size of the gold colloid precursor. Deposition of gold NPs smaller than 2 nm onto POM (Au/POM) was essential for a high catalytic activity for CO oxidation. The temperature for 50 % CO conversion was −67 °C. The catalyst showed extremely high stability for at least one month at 0 °C with full conversion. The catalytic activity and the reaction mechanism drastically changed at temperatures higher than 40 °C, showing a unique behavior called a U‐shaped curve. It was revealed by IR measurement that Auδ+ was a CO adsorption site and that adsorbed water promoted CO oxidation for the Au/POM catalyst. This is the first report on CO oxidation utilizing Au/POMs catalysts, and there is a potential for expansion to various gas‐phase reactions. 相似文献
13.
Carbon Monoxide Oxidation by Polyoxometalate‐Supported Gold Nanoparticulate Catalysts: Activity,Stability, and Temperature‐ Dependent Activation Properties
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Dr. Takuya Yoshida Prof. Dr. Toru Murayama Prof. Dr. Norihito Sakaguchi Prof. Dr. Mitsutaka Okumura Prof. Dr. Tamao Ishida Prof. Dr. Masatake Haruta 《Angewandte Chemie (International ed. in English)》2018,57(6):1523-1527
Nanoparticulate gold supported on a Keggin‐type polyoxometalate (POM), Cs4[α‐SiW12O40]?n H2O, was prepared by the sol immobilization method. The size of the gold nanoparticles (NPs) was approximately 2 nm, which was almost the same as the size of the gold colloid precursor. Deposition of gold NPs smaller than 2 nm onto POM (Au/POM) was essential for a high catalytic activity for CO oxidation. The temperature for 50 % CO conversion was ?67 °C. The catalyst showed extremely high stability for at least one month at 0 °C with full conversion. The catalytic activity and the reaction mechanism drastically changed at temperatures higher than 40 °C, showing a unique behavior called a U‐shaped curve. It was revealed by IR measurement that Auδ+ was a CO adsorption site and that adsorbed water promoted CO oxidation for the Au/POM catalyst. This is the first report on CO oxidation utilizing Au/POMs catalysts, and there is a potential for expansion to various gas‐phase reactions. 相似文献
14.
Mingquan Guo Bill X. Huang Hee‐Yong Kim 《Rapid communications in mass spectrometry : RCM》2009,23(13):1885-1891
Amide hydrogen exchange coupled to nano‐electrospray ionization mass spectrometry (nano‐ESI‐MS) has been used to identify and characterize localized conformational changes of Akt upon activation. Active or inactive Akt was incubated in D2O buffer, digested with pepsin, and analyzed by nano‐ESI‐MS to determine the deuterium incorporation. The hydrogen/deuterium (H/D) exchange profiles revealed that Akt undergoes considerable conformational changes in the core structures of all three individual domains after activation. In the PH domain, four β‐strand (β1, β2 β5 and β6) regions containing membrane‐binding residues displayed higher solvent accessibility in the inactive state, suggesting that the PH domain is readily available for the binding to the plasma membrane for activation. In contrast, these β‐strands became less exposed or more folded in the active form, which is favored for the dissociation of Akt from the membrane. The beginning α‐helix J region and the C‐terminal locus (T450‐470P) of the regulatory domain showed less folded structures that probably enable substrate entry. Our data also revealed detailed conformational changes of Akt in the kinase domain due to activation, some of which may be attributed to the interaction of the basic residues with phosphorylation sites. Our H/D exchange results indicating the conformational status of Akt at different activation states provided new insight for the regulation of this critical protein involved in cell survival. Published in 2009 by John Wiley & Sons, Ltd. 相似文献
15.
16.
《中国化学》2018,36(7):639-643
Two types of CeO2 nanocubes (average size of 5 and 20 nm, respectively) prepared via the hydrothermal process were selected to load gold species via a deposition‐precipitation (DP) method. Various measurements, including X‐ray diffraction (XRD), Raman spectra, high resolution transmission electron microscopy (HRTEM), in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS), and temperature‐programmed reduction by hydrogen (H2‐TPR), were applied to characterize the catalysts. It is found that the sample with ceria size of 20 nm (Au/CeO2‐20) was covered by well dispersed both Au3+ and Auδ+ (0 < δ < 1). For the other sample with ceria size of 5 nm (Au/CeO2‐5), Au3+ is the dominant gold species. Au/CeO2‐20 performed better catalytic activity for CO oxidation because of the strong CO adsorption of Auδ+ in the catalysts. The catalytic activity of Au/CeO2‐5 was improved due to the transformation of Au3+ to Auδ+. Based on the CO oxidation and in situ DRIFTS results, Auδ+ is likely to play a more important role in catalyzing CO oxidation reaction. 相似文献
17.
Hepatitis C Virus (HCV) is associated with a severe liver disease and increased frequency in the development of hepatocellular carcinoma. Overexpression of HCV core protein is known to transform fibroblast cells. Phospholipase D (PLD) activity is commonly elevated in response to mitogenic signals, and has also been overexpressed and hyperactivated in some human cancer cells. The aim of this study was to understand how PLD was regulated in the HCV core protein-transformed NIH3T3 mouse fibroblast cells. We observed that PLD activity was elevated in the NIH3T3 cells overexpressing HCV core protein over the vector alone-transfected control cells, however, expression levels of PLD protein and protein kinase C (PKC) in the HCV core protein-transformed cells was similar to the control cells. Phorbol 12-myristate 13-acetate (PMA), which is known to activate PKC, stimulated PLD activity significantly more in the core protein-transformed cells, in comparison with that of the control cells. PLD activity assay using PKC isozyme-specific inhibitor and PKC translocation experiment showed that PKC-delta was mainly involved in the PMA- induced PLD activation in the core-transformed cells. Moreover, in cells overexpressing HCV core protein, PMA also stimulated p38 kinase more potently than that of the control cells, and an inhibitor of p38 kinase abolished PMA-induced PLD activation in cells overexpressing HCV core protein. Taken together, these results suggest that PLD might be implicated in core protein-induced transformation. 相似文献
18.
Mononuclear Nonheme High‐Spin (S=2) versus Intermediate‐Spin (S=1) Iron(IV)–Oxo Complexes in Oxidation Reactions
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Seong Hee Bae Dr. Mi Sook Seo Dr. Yong‐Min Lee Dr. Kyung‐Bin Cho Prof. Dr. Won‐Suk Kim Prof. Dr. Wonwoo Nam 《Angewandte Chemie (International ed. in English)》2016,55(28):8027-8031
Mononuclear nonheme high‐spin (S=2) iron(IV)–oxo species have been identified as the key intermediates responsible for the C?H bond activation of organic substrates in nonheme iron enzymatic reactions. Herein we report that the C?H bond activation of hydrocarbons by a synthetic mononuclear nonheme high‐spin (S=2) iron(IV)–oxo complex occurs through an oxygen non‐rebound mechanism, as previously demonstrated in the C?H bond activation by nonheme intermediate (S=1) iron(IV)–oxo complexes. We also report that C?H bond activation is preferred over C=C epoxidation in the oxidation of cyclohexene by the nonheme high‐spin (HS) and intermediate‐spin (IS) iron(IV)–oxo complexes, whereas the C=C double bond epoxidation becomes a preferred pathway in the oxidation of deuterated cyclohexene by the nonheme HS and IS iron(IV)–oxo complexes. In the epoxidation of styrene derivatives, the HS and IS iron(IV) oxo complexes are found to have similar electrophilic characters. 相似文献
19.
The total synthesis of the diarylheptanoids (?)‐diospongin A ( 1 ) and B ( 2 ) was achieved stereoselectively via the δ‐lactone intermediate 6 . The key reactions involved are a stereoselective reduction of β‐keto ester and the Horner–Wadsworth–Emmons and intramolecular oxy‐Michael reactions. 相似文献
20.
Dirk Lützenkirchen‐Hecht Hans‐Henning Strehblow 《Surface and interface analysis : SIA》2009,41(10):820-829
Silver (II) oxide layers (AgO) were prepared by anodic oxidation of pre‐oxidized, Ag2O‐covered silver electrodes in 1 M NaOH (pH 13.8). The oxidized electrodes were investigated using a combination of electrochemical techniques, ex situ X‐ray photoelectron spectroscopy (XPS) and in situ surface‐sensitive grazing incidence X‐ray absorption spectroscopy (EXAFS) under full potential control. The application of these different techniques leads to a detailed, consistent picture of the anodic silver (II) oxide layer formation. The experiments have shown that the chemical composition of the AgO layer varies significantly with oxidation potential, revealing a decreasing oxygen deficiency with increasing anodization potential and oxidation time. XPS as well as EXAFS experiments support the interpretation of the oxide as a mixed valence Ag + Ag3 + O2 with different contributions of Ag + and Ag3 + species, depending on potential and anodization time. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献