Synthesis of N-arylpyridinium salts bearing a nitrone spin trap as potential mitochondria-targeted antioxidants

The generation of excess reactive oxygen species (ROS) in mitochondria is responsible for much of the oxidative stress associated with ageing (aging), and mitochondrial dysfunction is part of the pathology of neurodegeneration and type 2 diabetes. Lipophilic pyridinium ions are known to accumulate in mitochondria and this paper describes a general route for the preparation of nitrone-containing N-arylpyridinium salts having a range of lipophilicities, as potential therapeutic antioxidants. The compatibility of nitrones with the Zincke reaction is the key to their synthesis. Their trapping of carbon-centred radicals and the EPR spectra of the resulting nitroxides are reported

High binding yet accelerated guest rotation within a cucurbit[7]uril complex. Toward paramagnetic gyroscopes and rolling nanomachines †

International audienceThe (15-oxo-3,7,11-triazadispiro[5.1.5.3]hexadec-7-yl)oxidanyl, a bis-spiropiperidinium nitroxide derived from TEMPONE, can be included in cucurbit[7]uril to form a strong (K a ∼ 2 × 10 5 M −1) CB[7]@bPTO complex. EPR and MS spectra, DFT calculations, and unparalleled increased resistance (a factor of ∼10 3) toward ascorbic acid reduction show evidence of deep inclusion of bPTO inside CB[7]. The unusual shape of the CB[7]@bPTO EPR spectrum can be explained by an anisotropic Brownian rotational diffusion, the global tumbling of the complex being slower than rotation of bPTO around its " long molecular axis " inside CB[7]. The CB[7] (stator) with the encapsulated bPTO (rotator) behaves as a supramolecular para-magnetic rotor with increased rotational speed of the rotator that has great potential for advanced nano-scale machines requiring wheels such as cucurbiturils with virtually no friction between the wheel and the axle for optimum wheel rotation (i.e. nanopulleys and nanocars)

Nitroxide Radicals with Cucurbit[n]urils and Other Cavitands

WOS:000430466900016The interface of nitroxide radicals with cucurbit[n]urils (CB[n]) is covered in this review. Either used as spin probes, spin labels, or stoppers for paramagnetic rotaxanes, nitroxides offer new opportunities to investigate CB[n] and their inclusion complexes, especially thanks to EPR spectroscopy. On the other hand, CB[n] also offer interesting opportunities to modulate nitroxide properties such as protection or structuring. The multiple back and forth between the two well-established areas where nitroxides bring information about CB[n], and CB[n] modulate nitroxide properties, have enabled to shed some light at this new interesting interface

The Diversity of Cucurbituril Molecular Switches and Shuttles

International audienceAbstract Ring translocation switches and shuttles featuring a macrocycle (or a ring molecule) navigating between two or more stations continue to attract attention. While the vast majority of these systems are developed in organic solvents, the cucurbituril (CB) macrocycles are ideally suited to prepare such systems in water. Indeed, their stability and their relatively high affinity for relevant guest molecules are key attributes toward translating the progresses made in organic solvents, into water. This concept article summarizes the findings, key advances and multiple possibilities offered by CBs toward advanced molecular switches and shuttles in water

Développement de pièges à radicaux libres dérivés de b-cyclodextrines pour l'étude in vitro et in vivo des situations de stress oxydatif

L'influence de b-cyclodextrines (b-CDs) sur la détection du radical anion superoxyde (O2.-) responsable de pathologies liées au stress oxydatif a été étudiée par la technique du piégeage de SPIN couplé à la RPE. Des nitrones de type PBN et EMPO ont été préparées. Les adduits superoxyde sont complexés par la DM-b-CD et la RM-b-CD et montrent des constantes d'association supérieures à celles des équilibres nitrone-CD. Les adduits les plus stables donnent les nitroxydes résistant le mieux à la bioréduction. Un nitroxyde de type TIPNO-TM-b-CD a ensuite été préparé (236CDTIPNO) et s'auto-associe dans l'eau entre formes faiblement et fortement complexées avec une barrière de 30 kJ.mol-1. La PBN a ensuite été liée de façon covalente à la TM-b-CD (236CDPBN) et la DM-b-CD (26CDPBN), et la DEPMPO liée à la TM-b-CD (236CDDEP). L'auto-inclusion des nitrones dans l'eau, le piégeage radicalaire et la résistance à la bioréduction des adduits du superoxyde ont été évalués.AIX-MARSEILLE1-BU Sci.St Charles (130552104) / SudocSudocFranceF