Cationic cyclodextrins: cell penetrating agents and other diverse applications

A novel cationic β-cyclodextrin decorated with a choline-like pendant exhibits Iodophor, Mucoadhesive and bactericidal properties

Iodine is a vital microelement and a powerful antiseptic with a rapid and broad spectrum of action. The development of iodophor compounds to improve the solubility and stability of iodine is still challenging. Here, we report the synthesis of a novel cationic β-cyclodextrin bearing a choline-like pendant (β-CD-Chol) designed to complex and deliver iodine to bacterial cells. The characterization of β-CD-Chol and the investigation of the inclusion complex with iodine were performed by NMR spectroscopy, mass spectrometry, UV-vis spectrophotometry, isothermal titration calorimetry, and dynamic light scattering. The functionalization with the positively charged unit conferred improved water-solubility, mucoadhesivity, and iodine complexation efficiency to the β-CD scaffold. The water-soluble β-CD-Chol/iodine complex efficiently formed both in solution and by solid-vapor reaction. The solid complex exhibited a significant stability for months. Iodine release from the inclusion complex was satisfactory and the bactericidal activity was proved against a Staphylococcus epidermidis strain. The absence of cytotoxicity tested on human keratinocytes and the improved mucoadhesivity make β-CD-Chol a promising drug delivery system and an appealing iodophor candidate for iodine-based antisepsis including mucosa disinfection.

Peptide-Appended Permethylated β-Cyclodextrins with Hydrophilic and Hydrophobic Spacers

A novel synthetic methodology, employing a combination of the strain-promoted azide–alkyne cycloaddition and maleimide–thiol reactions, for the preparation of permethylated β-cyclodextrin-linker-peptidyl conjugates is reported. Two different bifunctional maleimide cross-linking probes, the polyethylene glycol containing hydrophilic linker bicyclo[6.1.0] nonyne-maleimide and the hydrophobic 5′-dibenzoazacyclooctyne-maleimide, were attached to azide-appended permethylated β-cyclodextrin. The successfully introduced maleimide function was exploited to covalently graft a cysteine-containing peptide (Ac-Tyr-Arg-Cys-Amide) to produce the target conjugates. The final target compounds were isolated in high purity after purification by isocratic preparative reverse-phase high-performance liquid chromatography. This novel synthetic approach is expected to give access to many different cyclodextrin–linker peptides.

Enhanced delivery of daidzein into fibroblasts and neuronal cells with cationic derivatives of gamma-cyclodextrin for the control of cellular glycosaminoglycans

Two cationic derivatives of γ-cyclodextrin (GCD) were synthesized by functionalization with glycidyltrimethylammonium chloride (GTMAC) and ethylenediamine (EDA). Both these derivatives (GCD-GTMAC and GCD-EDA) have been shown to interact strongly with anionic biopolymers, unfractionated heparin (UFH) and mucin, the latter showing their mucoadhesive properties. They form inclusion complexes with daidzein (DAI), an isoflavone displaying a multitude of physiological effects, much more efficiently than the unmodified GCD. It was also shown that the complexes of these GCD derivatives with DAI and Nile Red penetrate human fibroblasts and murine hippocampal neuronal cells indicating that cationic GCD derivatives can be considered as potential delivery systems for isoflavones and other poorly water soluble compounds. Moreover, it was found that DAI delivered in cationic GCD complexes decreased the level of the cellular glycosaminoglycans (GAGs) in normal fibroblasts suggesting their possible application in the control of GAGs in mucopolysaccharidoses, lysosomal storage diseases caused by pathological accumulation of GAGs in the cells.

Applications of supramolecular capsules derived from resorcin[4]arenes, calix[n]arenes and metallo-ligands: from biology to catalysis

This review summarizes supramolecular capsules based on resorcin[4]arenes, calix[n]arenes and metal–ligands, having concrete applications in biomedical field, catalysis and material science.

Cyclodextrin-based multivalent glycodisplays: covalent and supramolecular conjugates to assess carbohydrate-protein interactions

Covalent attachment of biorecognizable sugar ligands in several copies at precise positions of cyclomaltooligosaccharide (cyclodextrin, CD) macrocycles has proven to be an extremely flexible strategy to build multivalent conjugates. The commercial availability of the native CDs in three different sizes, their axial symmetry and the possibility of position- and face-selective functionalization allow a strict control of the valency and spatial orientation of the recognition motifs (glycotopes) in low, medium, high and hyperbranched glycoclusters, including glycodendrimer-CD hybrids. "Click-type" ligation chemistries, including copper(i)-catalyzed azide-alkyne cycloaddition (CuAAC), thiol-ene coupling or thiourea-forming reactions, have been implemented to warrant full homogeneity of the adducts. The incorporation of different glycotopes to investigate multivalent interactions in heterogeneous environments has also been accomplished. Not surprisingly, multivalent CD conjugates have been, and continue to be, major actors in studies directed at deciphering the structural features ruling carbohydrate recognition events. Nanometric glycoassemblies endowed with the capability of adapting the inter-saccharide distances and orientations in the presence of a receptor partner or capable of mimicking the fluidity of biological membranes have been conceived by multitopic inclusion complex formation, rotaxanation or self-assembling. Applications in the fields of sensors, site-specific drug and gene delivery or protein stabilization attest for the maturity of the field.