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41.
Stephane Fontanay Francine Kedzierewicz Raphael Emmanuel Duval Igor Clarot 《Journal of inclusion phenomena and macrocyclic chemistry》2012,73(1-4):341-347
Hydroxy pentacyclic triterpenoic acids (HPTAs) have been described to exhibit numerous pharmacological properties. They also exhibit poor hydrosolubility, thus affecting their potential clinical interest. The association of these active substances with cyclodextrins could be employed to improve some properties such as bioavailability and activity. 1:1 Inclusion complexes of ursolic, oleanolic and betulinic acids with γ-cyclodextrin were evaluated by DSC and 1H NMR spectroscopy. The apparent formation constants (Kf) of the formed complexes were determined using RP-HPLC. Thermodynamic parameters ΔGo, ΔHo and ΔSo were calculated with temperatures ranging from 25 to 45?°C to evaluate the complexation process. Finally the influence of γ-CD on the HPTA water solubility was investigated by phase-solubility studies. 相似文献
42.
Romain Sallio Stéphane Lebrun Francine Agbossou-Niedercorn Christophe Michon Eric Deniau 《Tetrahedron: Asymmetry》2012,23(13):998-1004
Two alternative synthetic approaches to a variety of enantioenriched 6-arylated piperidin-2-ones have been developed. The first one is based on the hydrogenation of suitably arylated chiral cyclic enehydrazides. The second approach relies on the asymmetric catalytic hydrogenation of the corresponding N-alkylated precursors. 相似文献
43.
Paul Ionut Dron Francine Cazier David Landy Gheorghe Surpateanu 《Supramolecular chemistry》2013,25(5):473-477
The first results of the complexing ability of cyclobis-(paraquat-p-phenylene) as supramolecular host with different aromatic volatile organic compounds are presented. The formation constants of cyclobis(paraquat-p-phenylene) with toluene and halogenobenzenes were determined in aqueous solution by static headspace associated with gas chromatography and compared with the ones obtained by cyclodextrins. The data indicated the formation of 1:1 inclusion compounds in both cases. The results underlined a greater complexation ability for cyclobis(paraquat-p-phenylene) which was confirmed by a theoretical study. 相似文献
44.
Rafaela G. Pozzobon Renata Rutckeviski Juliane Carlotto Vanessa S. Schneider Lucimara M. C. Cordeiro Graziele Francine Franco Mancarz Lauro M. de Souza Rosiane Guetter Mello Fhernanda Ribeiro Smiderle 《Molecules (Basel, Switzerland)》2023,28(1)
Liquidambar styraciflua L. is an aromatic species, popularly used in traditional Chinese medicine to treat diarrhea, dysentery, coughs, and skin sores. The present study was designed to investigate the chemical composition and biological potential of extracts obtained from the fruits of this plant. For the chemical evaluation, it was used mainly liquid and gas chromatography, plus NMR, and colorimetric methods. The aqueous extract (EA) originated two other fractions: an aqueous (P-EA) and an ethanolic (S-EA). The three extracts were composed of proteins, phenolic compounds, and carbohydrates in different proportions. The analyses showed that the polysaccharide extract (P-EA) contained pectic polysaccharides, such as acetylated and methyl esterified homogalacturonans together with arabinogalactan, while the fraction S-EA presented phenolic acids and terpenes such as gallic acid, protocathecuic acid, liquidambaric acid, combretastatin, and atractyloside A. EA, P-EA, and S-EA showed antioxidant activity, with IC50 values of 4.64 µg/mL, 16.45 µg/mL, and 3.67 µg/mL, respectively. The cytotoxicity followed the sequence S-EA > EA > P-EA, demonstrating that the toxic compounds were separated from the non-toxic ones by ethanol precipitation. While the fraction S-EA is very toxic to any cell line, the fraction P-EA is a promising candidate for studies against cancer due to its high toxicity to tumoral cells and low toxicity to normal cells. 相似文献
45.
Dieter Seebach Miguel A. Maestro Michael Sefkow Axel Neidlein Francine Sternleld Geo Adam Thimo Sommerfeld 《Helvetica chimica acta》1991,74(8):2112-2118
The antibiotic myxovirescine M2 was synthesized from seven building blocks ( 1 – 7 , Scheme 1), with the following chiral starting materials being employed: (S)-malic acid, (+)-D -ribonolactone, (S)-2-(hydroxymethyl)butanoate, and (2R,4S)-5-hydroxy-2,4-dimethylpenLanoate. Three new nucleophilic reagents, 8 – 10 , for C-C bond formation have been used. The key steps of the synthesis are: a Suzuki coupling between an alkyl borane and a vinyl bromide ( 4 + 12e → 13 ), a Julia olefinalion ( 14 + 17 → 18 ), and a Yamaguchi macrolactonizalion to form the 28-membered lactone ( 18 → 19 ), This extremely convergenl synthetic approach will allow the preparation of a number of the 31 known myxovirescine molecules. 相似文献
46.
A geometric model for active contours in image processing 总被引:58,自引:0,他引:58
Summary We propose a new model for active contours based on a geometric partial differential equation. Our model is intrinsec, stable (satisfies the maximum principle) and permits a rigorous mathematical analysis. It enables us to extract smooth shapes (we cannot retrieve angles) and it can be adapted to find several contours simultaneously. Moreover, as a consequence of the stability, we can design robust algorithms which can be engineed with no parameters in applications. Numerical experiments are presented. 相似文献
47.
Francine Blanger‐Garipy Michle Dartiguenave Frdrique Loiseau Andr L. Beauchamp 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):e338-e339
Pairs of individual molecules of the title compound, C19H17O2P, (I), containing tetrahedrally coordinated P atoms are connected across crystallographic inversion centres via complementary O—H?O=P hydrogen bonds. 相似文献
48.
Kivlehan F Lanyon YH Arrigan DW 《Langmuir : the ACS journal of surfaces and colloids》2008,24(17):9876-9882
This paper reports on the electrochemical behavior of bovine insulin at the interface between two immiscible electrolyte solutions (ITIES). The voltammetric ion-transfer response obtained in the presence of insulin was dependent on the aqueous phase pH conditions and on the nature of the organic phase electrolyte employed in experiments. Optimal detection was obtained at acidic pH below the isoelectric point of insulin where it was positively charged. A shift in transfer potentials to lower potential values was observed with decreasing hydrophobicity of the anion of the organic phase electrolyte. No ion-transfer response was observed at pH values of the aqueous phase above the isoelectric point, where insulin was negatively charged. These results suggest that the voltammetric response is due to ion-pairing interactions at the ITIES between positively charged insulin and the hydrophobic anion of the organic phase electrolyte, together with adsorption of the ion-pair at the interface. The voltammetric response was obtained for insulin at concentrations down to 1 muM. These results show that electrochemistry is useful in studying the behavior of this important protein molecule at the polarized water-1,2-DCE interface and provides an alternative detection mode for bioanalytical applications. 相似文献
49.
Leclercq L Suisse I Agbossou-Niedercorn F 《Chemical communications (Cambridge, England)》2008,(3):311-313
Biphasic hydroformylation of dec-1-ene and styrene, at commercially competitive rates, can be successfully performed in imidazolium triflate ionic liquids; the ionic liquid network forms 'inclusion complexes' with the phosphane ligands used to modify the rhodium catalyst. 相似文献
50.
Mouhamad Jida Guillaume Laconde Olivier-Mohamad Soueidan Nicolas Lebegue Germain Revelant Lydie Pelinski Francine Agbossou-Niedercorn Benoit Deprez Rebecca Deprez-Poulain 《Tetrahedron letters》2012,53(39):5215-5218
An efficient method for a stereoselective synthesis of optically pure N-Boc-3-arylpiperazines has been developed. After optimization of the protecting group strategy and experimental conditions, compounds were obtained via a highly stereoselective synthesis in up to 45% overall yield. This is a practical route to optically pure piperazines for medicinal chemistry. 相似文献