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Catalysis Communications 01/2012; 29:77-81. · 2.99 Impact Factor
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ABSTRACT: During the past fifteen years, the use of chemically modified cyclodextrins (CDs) in aqueous organometallic catalysis has significantly contributed to enlarge the application field of biphasic processes in chemistry. In this paper, we describe how these supramolecular receptors became one of the most efficient solutions to solve mass transfer problems in aqueous organometallic catalysis. The scientific gaps that have been cleared to explain the exact role of the CDs in these biphasic systems are especially emphasized. In particular, the impact of supramolecular interactions between chemically modified CDs and substrates, water soluble ligands or organometallic catalysts is addressed for a better understanding of the recognition processes involved in the catalytic reactions.
Current Organic Chemistry 07/2010; 14(13):1296-1307. · 3.06 Impact Factor
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Chemical Reviews 04/2006; 106(3):767-81. · 40.20 Impact Factor
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Advanced Synthesis & Catalysis 02/2006; 348(3):379 - 386. · 6.05 Impact Factor
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ABSTRACT: Association between doxorubicin (DOX) and gamma-cyclodextrin (gamma-CD) or hydroxypropyl-gamma-CD (HP-gamma-CD) has been examined to increase the delivery of this antitumoral agent to the brain. The stoichiometry and the stability constant of gamma-CD or HP-gamma-CD and DOX complexes were determined in physiological medium by UV-visible spectroscopy. By using an in vitro model of the blood-brain barrier (BBB), endothelial permeability and toxicity toward the brain capillary endothelial cells of DOX, gamma-CD, and HP-gamma-CD were performed. For each CD, endothelial permeability was relatively low and a disruption of the BBB occurred at 20 microM, 20 mM, and 50 mM DOX, gamma-CD, and HP-gamma-CD, respectively. Increasing amounts of CDs were added to a fixed DOX concentration. Addition of gamma-CD or HP-gamma-CD, up to 15 and 35 mM, respectively, decreased the DOX delivery, probably due to the low complex penetration across the BBB and the decrease in free DOX concentration. Higher CD concentrations increased the DOX delivery to the brain, but this effect is due to a loss of BBB integrity. In contrast to what was observed on Caco-2 cell model with various drugs, CDs are not able to increase the delivery of DOX across our in vitro model of BBB.
Journal of Pharmacology and Experimental Therapeutics 01/2005; 311(3):1115-20. · 3.83 Impact Factor
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ABSTRACT: Cyclodextrins (CDs) can be envisaged to cure some diseases related to the brain, but the behavior of these compounds toward the blood-brain barrier (BBB) remains largely unexplored to envisage such clinical applications. To fulfill this gap, the toxicity and endothelial permeability for native, methylated, and hydroxypropylated alpha-, beta-, and gamma-CDs have been studied on an in vitro model of BBB. As shown by the endothelial permeability for sucrose and immunofluorescence stainings, the native CDs are the most toxic CDs (alpha- > beta- > gamma-CD). Whereas the chemical modification of beta-CD did not affect the toxicity of this CD, differences are observed for the alpha- and gamma-CD. To determine the origin of toxicity, lipid effluxes on the brain capillary endothelial cells were performed in the presence of native CDs. It was found that alpha-CD removed phospholipids and that beta-CD extracted phospholipids and cholesterol. gamma-CD was less lipid-selective than the other CDs. Finally, the endothelial permeability of each CD has been determined. Surprisingly, no structure/permeability relationship has been observed according to the nature and chemical modifications of CDs.
Journal of Pharmacology and Experimental Therapeutics 08/2004; 310(2):745-51. · 3.83 Impact Factor
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ABSTRACT: The effect of methylated cyclodextrins on the RhH(CO)(TPPTS)3 complex in hydroformylation conditions [50 atm of CO/H2 (1/1) and 80 °C] has been investigated by high-pressure 31P{1H} NMR spectroscopy. In the presence of methylated β-cyclodextrin, the equilibria between the rhodium species lie in favor of phosphine low-coordinated rhodium species. The formation of a stable inclusion complex between this cyclodextrin and the trisulfonated triphenylphosphine ligand (TPPTS) was found to be the key to understanding the displacement of the equilibria. Indeed, the methylated α-cyclodextrin which does not interact with the TPPTS and the methylated γ-cyclodextrin which can weakly bind to the TPPTS have no and a very low effect on the equilibria, respectively. These results explain for the first time why a decrease in the normal to branched aldehydes ratio is always observed when cyclodextrins are used as mass-transfer agents in aqueous biphasic hydroformylation processes.
Advanced Synthesis & Catalysis 04/2004; 346(4):425 - 431. · 6.05 Impact Factor
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ABSTRACT: Cyclodextrins or calixarenes possessing extended hydrophobic host cavities and surface-active properties were found to be very efficient as mass transfer promoters for the palladium-mediated Suzuki cross-coupling reaction of 1-iodo-4-phenylbenzene and phenylboronic acid in aqueous medium. The cross-coupling rates were up to 92 times higher than those obtained without addition of any compound.
Advanced Synthesis & Catalysis 02/2004; 346(1):83 - 89. · 6.05 Impact Factor
