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991.
In the tetraalkylation of p-tert-butyl[3.1.3.1]homooxacalixarene with BrCH2CO2R and K2CO3 in acetone, the initially formed cone conformer is converted into the more stable 1,4-alternate conformer when R = Me or Et, but not when R = i-Pr or t-Bu. In the case of R = i-Pr, derivatives in fixed 1,4-alternate conformation and in partial cone conformation were also isolated. Compounds in fixed cone conformation are good ligands for tetramethylammonium, acetylcholine, and N-methylpyridinium salts in CDCl3, but the partial cone isomer proved to be somewhat better and even the 1,4-alternate conformer turned out to be active. The possible involvement of the ester functions as additional binding sites is discussed; moreover, an insight into the energetics of the complexation and conformational isomerization processes is given. 相似文献
992.
A method for pharmacokinetic studies using cassette dosing associated with serial bleeding in mice is described. PK profiles of four soluble epoxide hydrolase inhibitors were determined following oral, subcutaneous or intraperitoneal administration individually or in cassette dosing. Parent analyses were performed on only 5 μL of whole blood from serial bleeds (up to 10 per animal), by LC/MS/MS. An accuracy (88-100%) and precision (<10% RSD) were observed, leading to reliable datum points for PK calculation. PK profiles, Tmax, Cmax and half-life values after cassette dosing were similar to the individual PK results. This method dramatically increases speed of data collection while dramatically reducing cost and animal usage. The results presented here clearly indicate that this proposed method could be applicable to high-throughput PK studies. 相似文献
993.
The use of photolinkers (photoactivatable heterobifunctional crosslinkers) is a popular method to attach biomolecules to polymer
surfaces. This study addresses the selection of photolinker and the adjustment of reaction conditions, such as the concentration
of biomolecule applied, and irradiation time. The influence of these variables are investigated for four prominent photolinkers:
ketyl-reactive benzophenone (BP) and anthraquinone (AQ), nitrene-reactive nitrophenyl azide (NPA), and carbene-reactive phenyl-(trifluoromethyl)diazirine
(PTD). The influence of substrate material is discussed, and three different polymers served as representative substrates:
poly(methyl methacrylate) (PMMA), polystyrene (PS), and a cycloolefin copolymer (COC). We compared the overall photolinking
efficiency of all photolinkers with respect to the polymer substrate they are applied to, and we found considerable differences
for certain photolinker/substrate combinations. Of all photolinkers and substrates tested, PTD as photolinker and COC as substrate
showed the highest photolinking efficiencies and fastest reaction times. For this study DNA oligonucleotides were chosen as
a model system of biomolecular probes, and fluorescence detection of DNA microarrays served as method of detection. 相似文献
994.
[reaction: see text] The 1-fluoro-1-haloalkenes undergo Pd-catalyzed Negishi cross-couplings with primary alkylzinc bromides to give multisubstituted fluoroalkenes. The alkylation was trans-selective giving pure Z-fluoroalkenes in most cases. The highest yields were obtained with Pd2(dba)3 and PdCl2(dppb) catalysts but the best stereochemical outcome was obtained with less reactive Pd(PPh3)4. The tertiary alkylzincs also produced desired fluoroalkenes in high yields. Coupling of beta,beta-dichlorostyrene with organozinc reagent resulted in the formation of monocoupled product. 相似文献
995.
Gentili A Sergi M Perret D Marchese S Curini R Lisandrin S 《Rapid communications in mass spectrometry : RCM》2006,20(12):1845-1854
Within the European Union the use of anabolic steroids for promoting growth and improving meat-to-fat ratio in food-producing animals has been banned since 1988. For the unequivocal identification of hormone residues in a complex matrix such as meat we have developed a rapid, specific and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method, in combination with a simple extraction procedure based on the matrix solid-phase dispersion (MSPD). The performances of a triple quadrupole (QqQ) and a quadrupole/time-of-flight (QqTOF) were compared: the QqQ mass spectrometer was found to be more sensitive for almost all studied analytes, but the selectivity was superior using the QqTOF system; the full-scan spectra (acquired without losing sensitivity), mass accuracy and resolution of the hybrid instrument enabled a more probatory analyte identification than that obtained selecting two multiple-reaction monitoring (MRM) transitions with a QqQ. Average recoveries ranged from 80 to 100%, and the detection capabilities (CCbetas) were less than 1.06 ppb with the QqQ instrument and less than 5.20 ppb with the QqTOF instrument for the bovine meat, which proved to be the most complex matrix. 相似文献
996.
997.
Schuster D Laggner C Steindl TM Palusczak A Hartmann RW Langer T 《Journal of chemical information and modeling》2006,46(3):1301-1311
Cytochrome P450 19 (P450 19, aromatase) constitutes a successful target for the treatment of breast cancer. This study analyzes chemical features common to P450 19 inhibitors to develop ligand-based, selective pharmacophore models for this enzyme. The HipHop and HypoRefine algorithms implemented in the Catalyst software package were employed to create both common feature and quantitative models. The common feature model for P450 19 includes two ring aromatic features in its core and two hydrogen bond acceptors at the ends. The models were used as database search queries to identify active compounds from the NCI database. 相似文献
998.
Daniela Tardito Marco Milanese Tiziana Bonifacino Laura Musazzi Massimo Grilli Alessandra Mallei Elisabeth Mocaer Cecilia Gabriel-Gracia Giorgio Racagni Maurizio Popoli Giambattista Bonanno 《BMC neuroscience》2010,11(1):1-4
Background
Agomelatine is a melatonergic receptor agonist and a 5HT2C receptor antagonist that has shown antidepressant efficacy. In order to analyze separately the effect of the two receptorial components, rats were chronically treated with agomelatine, melatonin (endogenous melatonergic agonist), or S32006 (5-HT2C antagonist), and then subjected to acute footshock-stress.Results
Only chronic agomelatine, but not melatonin or S32006, completely prevented the stress-induced increase of glutamate release in the rat prefrontal/frontal cortex.Conclusions
These results suggest a potential synergy between melatonergic and serotonergic pathways in the action of agomelatine. 相似文献999.
Moises A. da Silva Daniela C. de Oliveira Andrea T. Papacidero Cesar Mello Eduardo J. Nassar Katia J. Ciuffi Hérica C. Sacco 《Journal of Sol-Gel Science and Technology》2003,26(1-3):329-334
This work describes the preparation of the iron (III) porphyrin, FeTDCNO2, entrapped in a silica matrix in the form of powder (FePD) or thin film using the sol-gel process. The films were obtained from sols using the dip-coating technique. The variables involved in the FePD preparation were analysed by a fractional factorial design with resolution 5, designated by 2
V
5 – 1. The variables which present a positive effect and maximise the loading of the studied ironporphyrin on the FePD material are solvent, water volume and reaction time. The utilization of pyridine or imidazole as template does not affect the preparation of the FePD material. The UV-visible absorption spectra of all prepared materials present the characteristic Soret band of ironporphyrins at 419–420 nm.The materials were analysed by thermogravimetric analysis, isotherm of nitrogen adsorption, 29Si NMR and scanning electron micrograph. The catalytic performance of FePD-imidazole on the epoxidation of z-cyclooctene with iodosylbenzene is similar to that of FeTDCNO2 in homogeneous solution (60 and 52%). 相似文献
1000.
Fuquan Song Daniela Pappalardo Anthony F. Johnson Bernhard Rieger Manfred Bochmann 《Journal of polymer science. Part A, Polymer chemistry》2002,40(10):1484-1497
The copolymerization of propene with 7‐methyl‐1,6‐octadiene (MOD) catalyzed by Cp*TiMe3/B(C6F5)3 ( A ) and rac‐C2H4(Ind)2ZrCl2/methylaluminoxane ( B ) in toluene under 1 bar propene gave copolymers with unsaturated side chains. Under these conditions, catalyst A produced copolymers with an atactic backbone structure of type 1 , with 3.5–19.6 mol % MOD incorporation and weight‐average molecular weight = 0.7–2.7 × 105. Using catalyst B , copolymers 2 with 0.4–3.8 mol % MOD incorporation were prepared. The comonomer incorporation was a linear function of the feed ratio. The titanium catalyst A had a significantly higher affinity for MOD than the sterically more hindered zirconocene B . Postpolymerization modification of the side‐chain C?C bond allowed the facile introduction of a wide variety of functional groups. Epoxidation and especially ozonolysis of the C?C bond, to give ? CHO and ? COOH functionalized copolymers, proved to be very facile routes to functionalized polypropenes. According to monitoring by NMR, most of these transformations proceed in an essentially quantitative conversion. As an example of potential applications of such polymers, polypropenes with covalently attached dyes were prepared that are suitable for blending. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1484–1497, 2002 相似文献