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21.
Haggenmueller R Rahatekar SS Fagan JA Chun J Becker ML Naik RR Krauss T Carlson L Kadla JF Trulove PC Fox DF Delong HC Fang Z Kelley SO Gilman JW 《Langmuir : the ACS journal of surfaces and colloids》2008,24(9):5070-5078
The use of single wall carbon nanotubes (SWCNTs) in current and future applications depends on the ability to process SWCNTs in a solvent to yield high-quality dispersions characterized by individual SWCNTs and possessing a minimum of SWCNT bundles. Many approaches for the dispersion of SWCNTs have been reported. However, there is no general assessment which compares the relative quality and dispersion efficiency of the respective methods. Herein we report a quantitative comparison of the relative ability of "wrapping polymers" including oligonucleotides, peptides, lignin, chitosan, and cellulose and surfactants such as cholates, ionic liquids, and organosulfates to disperse SWCNTs in water. Optical absorption and fluorescence spectroscopy provide quantitative characterization (amount of SWCNTs that can be suspended by a given surfactant and its ability to debundle SWCNTs) of these suspensions. Sodium deoxy cholate (SDOCO), oligonucleotides (GT)(15), (GT)(10), (AC)(15), (AC)(10), C(10-30), and carboxymethylcellulose (CBMC-250K) exhibited the highest quality suspensions of the various systems studied in this work. The information presented here provides a good framework for further study of SWCNT purification and applications. 相似文献
22.
Bioorthogonal Probes for the Study of MDM2‐p53 Inhibitors in Cells and Development of High‐Content Screening Assays for Drug Discovery
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Pier Luca D'Alessandro Nicole Buschmann Markus Kaufmann Dr. Pascal Furet Frederic Baysang Reto Brunner Dr. Andreas Marzinzik Dr. Thomas Vorherr Dr. Therese‐Marie Stachyra Dr. Johannes Ottl Dr. Dimitrios E. Lizos Dr. Amanda Cobos‐Correa 《Angewandte Chemie (International ed. in English)》2016,55(52):16026-16030
To study the behavior of MDM2‐p53 inhibitors in a disease‐relevant cellular model, we have developed and validated a set of bioorthogonal probes that can be fluorescently labeled in cells and used in high‐content screening assays. By using automated image analysis with single‐cell resolution, we could visualize the intracellular target binding of compounds by co‐localization and quantify target upregulation upon MDM2‐p53 inhibition in an osteosarcoma model. Additionally, we developed a high‐throughput assay to quantify target occupancy of non‐tagged MDM2‐p53 inhibitors by competition and to identify novel chemical matter. This approach could be expanded to other targets for lead discovery applications. 相似文献
23.
Renato Galli Markus Dobler Rolf Güller Reto Stahl Hans‐Jürg Borschberg 《Helvetica chimica acta》2002,85(10):3400-3413
Two independent total syntheses of the Aristotelia alkaloid (−)‐serratenone ((−)‐ 1 ) are disclosed, one starting with (−)‐α‐pinene, the other one with (S)‐α‐terpineol. These correlations led to a revision of the originally proposed absolute configuration of the natural product. In the course of systematic investigations of the behavior of the indole alkaloids (+)‐makomakine ((+)‐ 18 ) and (−)‐hobartine ((−)‐ 22 ) towards oxidizing reagents, it was found that treatment with I2 leads to no less than five different products. Depending on the exact reaction conditions, each of them can be obtained as the major component in yields between 40 and 60%. One of these compounds was shown to be identical with the natural product (+)‐11,12‐didehydromakonin‐10‐one ((+)‐ 28 ). 相似文献
24.
Heinrich Berger Werner Seebacher Marcel Kaiser Reto Brun Robert Saf Robert Weis 《Monatshefte für Chemie / Chemical Monthly》2009,31(6):495-502
Abstract
Several 4-amino-6,7-diarylbicyclo[2.2.2]octan-2-ols bearing varying substituents on the aromatic rings were synthesized following a manual method for applying the Hansch approach. All new compounds were tested for their activity against the causative organisms of East African sleeping sickness and malaria tropica. Structure activity relationships are discussed. 相似文献25.
Johanna Faist Werner Seebacher Marcel Kaiser Reto Brun Robert Saf Robert Weis 《Monatshefte für Chemie / Chemical Monthly》2009,31(6):1261-1268
Abstract
Aroyl derivatives of 2-aminobicyclo-octanes and 2-azabicyclo-nonanes have been synthesized and tested for their activities against the causative organisms of East African trypanosomiasis and malaria tropica. The acylation induced in general loss of antiprotozoal activity, but a single compound showed good antiplasmodial activity against a multiresistant strain of Plasmodium falciparum. 相似文献26.
Bringmann G Kajahn I Reichert M Pedersen SE Faber JH Gulder T Brun R Christensen SB Ponte-Sucre A Moll H Heubl G Mudogo V 《The Journal of organic chemistry》2006,71(25):9348-9356
The isolation and structural elucidation of three novel-type naphthylisoquinoline alkaloids, ancistrocladinium A and B (the latter along with its atropisomer), from a Congolese Ancistrocladus species collected in the habitat Yeteto is reported. Their structures, including all stereochemical features, were elucidated by spectroscopic, chemical, and chiroptical methods. Ancistrocladinium A and B are the first N,C-coupled naphthyldihydroisoquinoline alkaloids found in nature, i.e., with an iminium-aryl axis. Although ancistrocladinium A, which is N,8'-coupled, is configurationally stable at this axis, ancistrocladinum B and its rotational isomer are based on a hitherto unprecedented N,6'-coupling type, with a slow rotation about the hetero biaryl axis at room temperature; they thus occur as a 46:54 mixture of two configurationally semistable atropo-diastereomers. For the isomerization of (P)-ancistrocladinium B to its (M)-diastereomer and for the opposite direction, the Gibbs free energies of activation were determined to be DeltaG double dagger1 = 105.8 kJ mol-1 and DeltaG double dagger2 = 105.7 kJ mol-1, respectively. In addition, the compounds were shown to have promising antileishmanial activities. 相似文献
27.
Farimani MM Taheri S Ebrahimi SN Bahadori MB Khavasi HR Zimmermann S Brun R Hamburger M 《Organic letters》2012,14(1):166-169
Hydrangenone, a new heptacyclic isoprenoid with a 6/7/6/5/5 membered carbon ring skeleton, was isolated from the aerial parts of Salvia hydrangea. The structure was established by extensive NMR spectroscopic methods. The relative and absolute configuration of 1 was assigned by NOESY and X-ray crystallographic analysis and by comparison of experimental and calculated electronic circular dichroism (ECD) spectra. Compound 1 showed in vitro antiplasmodial activity, with an IC(50) value of 1.4 μM against P. falciparum. A plausible biosynthetic pathway of 1 was also proposed. 相似文献
28.
29.
Reto Beeli Mathias Steger Anthony Linden John A. Robinson 《Helvetica chimica acta》1996,79(8):2235-2248
A tricyclic diketopiperazine, formally derived by coupling (2S,4S)-4-aminoproline (Pro(NH2)) and (2S,4R)-4-(carboxymethyl)proline (Pro(CH2COOH)), is synthesized starting from readily available (2S,4R)-4-hydroxyproline. The resulting tricyclic template has carboxy and amino groups to which a peptide chain may be attached. The Fmoc-protected template 5 is incorporated into the cyclic molecule cyclo(-Ala1-Asn2-Pro3-Asn4-Ala5-) ( 6 ) where Pro(NH2)7 = Pro(CH2COOH)8 represents the template, using solid-phase peptide synthesis with cyclization in solution. The molecule is shown by NMR and dynamic simulated annealing methods to adopt a preferred conformation in aqueous solution, which includes an extended backbone at the residues Asn2-Pro3-Asn4, and a type-Iβ-turn at . These studies show that this novel template may be used in the synthesis of cyclic peptide and protein mimetics having defined secondary structure in aqueous environments. 相似文献
30.
Barium carbonate nanoparticles (50-100 nm) were prepared by flame spray pyrolysis. The rapid quenching during the preparation process resulted in the unprecedented formation of pure monoclinic BaCO3. The as-prepared materials were characterized by electron microscopy, X-ray diffraction as well as by thermogravimetric and differential scanning calorimetric analyses. At ambient conditions the metastable monoclinic phase transformed easily into the thermodynamically stable orthorhombic BaCO3 (witherite) within a few days. 相似文献