Unexpected Double Bank Shot of Diisobutylaluminium Hydride for Triple Functionalisation of -Cyclodextrin

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Cyclodextrins selectively modified on both rims using an O-3-debenzylative post-functionalisation, a consequence of the Sorrento meeting

International audienceA de-O-benzylation reaction induced by I-2-Et3SiH and developed by Iadonisi et al. on mono- and disaccharides was applied to per- or polybenzylated alpha-cyclodextrins to furnish compounds deprotected at position 3 of all sugar units. This methodology allows the straightforward post-functionalisation of the secondary rim of cyclodextrins already functionalised on their primary rim

Synthèse de dérivés de calix[6]arène fonctionnalisés par un bras triéthoxysilyle en vue d’applications en chromatographie gazeuse

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Développement de phases stationnaires de type sol-gel à base de dérives de calix[6]arène pour des applications en chromatographie en phase gazeuse

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Beta cyclodextrins bind, stabilize, and remove lipofuscin bisretinoids from retinal pigment epithelium

Accumulation of lipofuscin bisretinoids (LBs) in the retinal pigment epithelium (RPE) is the alleged cause of retinal degeneration in genetic blinding diseases (e.g., Stargardt) and a possible etiological agent for age-related macular degeneration. Currently, there are no approved treatments for these diseases; hence, agents that efficiently remove LBs from RPE would be valuable therapeutic candidates. Here, we show that beta cyclodextrins (β-CDs) bind LBs and protect them against oxidation. Computer modeling and biochemical data are consistent with the encapsulation of the retinoid arms of LBs within the hydrophobic cavity of β-CD. Importantly, β-CD treatment reduced by 73% and 48% the LB content of RPE cell cultures and of eyecups obtained from Abca4-Rdh8 double knock-out (DKO) mice, respectively. Furthermore, intravitreal administration of β-CDs reduced significantly the content of bisretinoids in the RPE of DKO animals. Thus, our results demonstrate the effectiveness of β-CDs to complex and remove LB deposits from RPE cells and provide crucial data to develop novel prophylactic approaches for retinal disorders elicited by LBs

Fluorescent Chemosensors for Anions and Contact Ion Pairs with a Cavity-Based Selectivity

The association of a concave macrocyclic compound to one or multiple fluorophores is an appealing strategy for the design of chemosensors. Indeed, as with biological systems, a cavity-based selectivity can be expected with such fluorescent receptors. Examples of calix[6]arene-based systems using this strategy are rare in the literature, and to our knowledge, no examples of fluorescent receptors that can bind organic contact ion pairs have been reported. This report describes the straightforward synthesis of fluorescent calix[6]arene-based receptors 4a and 4b bearing three pyrenyl subunits and the study of their binding properties toward anions and ammonium salts using different spectroscopies. It was found that receptor 4a exhibits a remarkable selectivity for the sulfate anion in DMSO, enabling its selective sensing by fluorescence spectroscopy. In CDCl3, the receptor is able to bind ammonium ions efficiently only in association with the sulfate anion. Interestingly, this cooperative binding of ammonium sulfate salts was also evidenced in a protic environment. Finally, a cavity-based selectivity in terms of size and shape of the guest was observed with both receptors 4a and 4b, opening interesting perspectives on the elaboration of fluorescent cavity-based systems for the selective sensing of biologically relevant ammonium salts such as neurotransmitters.SCOPUS: ar.jinfo:eu-repo/semantics/publishe