排序方式: 共有107条查询结果,搜索用时 31 毫秒
61.
Simone Veronique Fannang Victor Kuete Celine Djama Mbazoa Joseph Itbert Momo Hanh Trinh Van-Dufat Francois Tillequin Elisabeth Seguin Elizabeth Chosson Jean Wandji 《Chemistry of Natural Compounds》2011,47(3):404-407
A new acylated tritrepene, 3β-hexadecanoyloxy-lup-20(29)-en-21-ol (1), along with seven known compounds, lupeol (2), betulinic acid (3), ursonic acid (4), -sitosterol (5), β-stigmasterol (6), 3-O-β-D-glucopyranosyl-β-stigmasterol (7), and palmitic acid (8), were isolated from the leaves of Rauvolfia vomitoria (Apocynaceae). Their structures were established on the basis of spectroscopic
analysis and chemical evidence. The new acylated triterpene exhibited interesting antimicrobial activity against Candida albicans
(a yeast) with the MIC value 64 μg/mL. 相似文献
62.
Detection of the food allergen celery via loop-mediated isothermal amplification technique 总被引:1,自引:0,他引:1
Celine Zahradnik Roland Martzy Robert L. Mach Rudolf Krska Andreas H. Farnleitner Kurt Brunner 《Analytical and bioanalytical chemistry》2014,406(27):6827-6833
Since 2005, celery and celery products have to be labeled according to Directive 2003/89/EC due to their allergenic potential. In order to provide a DNA-based, rapid and simple detection method suitable for high-throughput analysis, a loop-mediated isothermal amplification (LAMP) assay for the detection of celery (Apium graveolens) was developed. The assay was tested for specificity for celery since closely related species also hold food relevance. The limit of detection (LOD) for spiked food samples was found to be as low as 7.8 mg of dry celery powder per kilogram. An evaluation of different amplification and detection platforms was performed to show reliable detection independent from the instrument used for amplification (thermal cycler or heating block) and detection mechanisms (real-time fluorescence detection, agarose gel electrophoresis or nucleic acid staining). The analysis of 10 commercial food samples representing diverse and complex food matrices, and a false-negative rate of 0 % for approximately 24 target copies or 0.08 ng celery DNA for three selected food matrices show that LAMP has the potential to be used as an alternative strategy for the detection of allergenic celery. The performance of the developed LAMP assay turned out to be equal or superior to the best available PCR assay for the detection of celery in food products. 相似文献
63.
Simo A. Mäkiharju Celine Gabillet Bu-Geun Paik Natasha A. Chang Marc Perlin Steven L. Ceccio 《Experiments in fluids》2013,54(7):1-21
To measure the void fraction distribution in gas–liquid flows, a two-dimensional X-ray densitometry system was developed. This system is capable of acquiring a two-dimensional projection with a 225 cm2 area of measurement through 21 cm of water. The images can be acquired at rates on the order of 1 kHz. Common sources of error in X-ray imaging, such as X-ray scatter, image distortion, veiling glare, and beam hardening, were considered and mitigated. The measured average void fraction was compared successfully to that of a phantom target and found to be within 1 %. To evaluate the performance of the new system, the flow in and downstream of a ventilated nominally two-dimensional partial cavity was investigated and compared to measurements from dual-tip fiber optical probes and high-speed video. The measurements were found to have satisfactory agreement for void fractions above 5 % of the selected void fraction measurement range. 相似文献
64.
Jana Sopkov‐de Oliveira Santos Diane Bauchart Celine Besset Isabelle Dez 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(10):o751-o753
The crystal structure of the title compound, C30H25ClN3O5P3, shows that the direct bonding between P and Cl does not modify the structural parameters in the vicinity of this P atom. It also confirms the structural difference between the two P atoms which are each bonded to two phenoxy groups, observed in the 31P NMR spectrum. The crystal packing consists principally of complex stacking interactions. 相似文献
65.
Kay CW Elsässer C Bittl R Farrell SR Thorpe C 《Journal of the American Chemical Society》2006,128(1):76-77
Pulsed electron-electron double resonance (ELDOR) has been used to obtain structural information from a FAD-dependent sulfhydryl oxidase, Augmenter of Liver Regeneration (ALR). ALR is a homodimer with each subunit containing a noncovalently bound FAD cofactor. Both FADs may be converted into the blue neutral radical form by aerobic treatment with DTT. From three-pulse and four-pulse ELDOR experiments, a distance of 26.1 +/- 0.8 A could be determined between the FAD cofactors in human ALR. Taking into account the electron spin density distribution in a neutral flavin radical obtained from density functional theory calculations, a distance of 26.9 A could be estimated for the separation of the spin centers in the X-ray structure of rat ALR. The good agreement confirms that rat ALR may be used as a model for mechanistic discussions of human ALR. The experiments also demonstrate that neutral flavin radicals have the appropriate properties to be used as intrinsic spin labels for distance determinations in proteins. 相似文献
66.
67.
Ying Wang Matthias Hamburger Celine H. K. Cheng Brenda Costall Robert J. Naylor Peter Jenner Kurt Hostettmann 《Helvetica chimica acta》1991,74(1):117-123
Ingestion of yellow star thistle (Centaurea solstitialis L.) by horses produces parkinsonism due to nigro-pallidal degeneration. The toxin responsible has not been identified so far. A CH2Cl2 extract from the aerial parts of C. solstitialis exhibited significant neurotoxicity against primary neuronal cultures of foetal rat brain. Activity-guided fractionation yielded the known sesquiterpene lactones solstitialin A ( 1 ), 13-0-acetylsolstitialin A ( 3 ), cynaropicrin ( 4 ), and the hitherto unknown 3-O-acetylsolstitialin A ( 2 ). In the bioassay with rat foetal full cell culture, 3 and 4 were toxic in a concentration-dependent manner and may be responsible for the ability of the plant to cause neurodegenerative changes in the brain of horses. 相似文献
68.
Darren Griffith Alberta Bergamo Sara Pin Marta Vadori Helge Müller-Bunz Gianni Sava Celine J. Marmion 《Polyhedron》2007
Herein, we describe the synthesis and characterisation of a novel class of PtII and PtIV pyridinehydroxamic acid (pyhaH) complexes of general formula cis-[PtIICl2(x-pyhaH)2] and cis-[PtIVCl4(x-pyhaH)2], respectively (where x = 3 or 4) in which the pyridinehydroxamic acid is coordinated to the platinum ion via the pyridine nitrogen only leaving the hydroxamic acid free to potentially release cytotoxic nitric oxide (NO). The crystal structure of the PtIV derivative, cis-[PtCl4(4-pyhaH)2] · 2CH3OH is reported. To establish the biological effect of the uncoordinated hydroxamic acid moiety in the PtII compounds synthesised, the corresponding pyridinecarboxylic acid (pycaH) complexes of general formula cis-[PtIICl2(x-pycaH)2] (where x = 3 or 4) and the PtII pyridine (py) complex, cis-[PtIICl2(py)2] were synthesised and served as reference standards. The NO-releasing properties of each of the PtII compounds, the pyhaH and the pycaH ligands were studied. The PtII pyridinehydroxamic acid derivatives were found to induce potent in vitro effects attributable to either NO-release from the hydroxamic acid moiety and/or stimulation of inducible nitric oxide synthase of endothelial cells. 相似文献
69.
Nicolas Mercier Antoine Seyeux Celine Morel Amedee Riou 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(2):m127-m128
The structure of the title hybrid salt, (C5H8NS)[SnCl3], is built up from segregated layers of organic cations and Sn polyhedra. [SnCl3]? groups are linked together by weak Sn?Cl interactions to form a one‐dimensional polymeric chain of anions. 相似文献
70.
Jason D. Masuda Dr. David Martin Dr. Celine Lyon‐Saunier Dr. Antoine Baceiredo Dr. Heinz Gornitzka Dr. Bruno Donnadieu Guy Bertrand Prof. 《化学:亚洲杂志》2007,2(1):178-187
The conjugate acids (PHCH+s) of P‐heterocyclic carbenes (PHCs) are prepared by formal [3+2] cycloaddition of a 1,3‐diphosphaallyl or 1,3‐phosphinophosphenium cation with various nitriles. The effect of the phosphorus substituent on the fate of the cyclization and on that of the counteranion and base in the subsequent deprotonation reaction are reported. Two PHCs that are indefinitely stable in the solid state are described. In solution, one of them, made from acetonitrile, undergoes a facile [3+2] cycloreversion, whereas the other, based on dimethyl cyanamide, is stable, presumably owing to its zwitterionic structure, which involves a tricoordinate pentavalent phosphorus atom. The reactivity of PHCs is strongly driven by the high electrophilicity of the phosphorus centers, as demonstrated by their reactivity with water and benzaldehyde. Although both PHCs reported in this paper are direct analogues of the least‐basic NHCs, their basicity is comparable to those of the more strongly basic NHCs (as determined by comparison of the carbonyl stretching frequencies of their corresponding cis‐[RhCl‐(CO)2(L)] complexes). 相似文献