Aromatic oligoamide foldamers as versatile scaffolds for induced circularly polarized luminescence at adjustable wavelengths

International audienceQuinoline oligoamide foldamers appended with non-chiral fluorophores and derivatized with a camphanyl chiral inducer display strong chiroptical properties at tunable wavelengths as proved by CD and CPL spectroscopies. Induced CPL activity with high luminescence dissymmetry factors was observed in the visible range at wavelengths specific to the fluorophores

Interlocked molecules : conception, photocapture and photoinduced commutation

L’implémentation d’un agent structurant impliquant un macrocycle à 31membres et intégrant un récepteur de type Hamilton / bis(2,6-diamidopyridine) a permis deconcevoir des [2]rotaxanes via une réaction click catalysée par du cuivre(I), soit à partir d’unpseudorotaxane en présence d’un barbiturique fonctionnalisé, soit par une méthode de« gabarit actif ». Ces structures supramoléculaires ont été rendues photochimiquement activesen exploitant des analogues de récepteurs Hamilton incorporant des groupementsphotodimérisables de type 9-anthracène. La photodimérisation et la retrodimérisation de cesrécepteurs en présence d’un fil barbiturique comportant des groupements terminauxencombrants (bouchons) permettent l’assemblage et le désassemblage de rotaxanes via unprocessus de photocapture. Ces unités 9-anthracène jouent également le rôle de bouchonsphotoactifs dans la formation d’un [2]rotaxane composé d’un plus petit anneau de typedibenzo-24-couronne-8, dont la photoirradiation résulte en une interconversion topologiqueinhabituelle entre un rotaxane et un caténane. Deux approches photochimiques ont permis deréguler des machines moléculaires distantes par une communication chimiqueintermoléculaire, c’est à dire soit par un transfert de molécule photoguidée, soit par untransfert d’électron photoinduit exalté par la présence d’un transfert d’énergie électroniqueréversible.A templating motif involving a 31-member macrocycle integrating a bis(2,6-diamidopyridine) / Hamilton-type receptor aided [2]rotaxane sythesis, via a copper(I)catalyzed Huisgen reaction, in the presence of a designer barbiturate or by functionalizationusing an active template synthesis. Homologous supramolecular structures were madephotochemically-active, harnessing Hamilton receptors incorporating photodimerizable 9-anthracene groups. Photodimerization and retrodimerisation of these receptors in the presence of a barbiturate thread bearing terminal bulky stopper groups permitted rotaxane assembly /disassembly. The 9-anthracene units serve as stoppers in the formation of a [2]rotaxanecompound comprising a smaller dibenzo-24-crown-8 ring. Photoirradiation of these photoactive stoppers results in an unusual all-optical topological rotaxane - catenaneinterconversion. Two approaches to photoregulate remote molecular machines byintermolecular chemical communication involving a photoguided molecule or by photoinduced electron transfer aided by reversible electronic energy transfer are considered

Molécules entrelacées : conception, photocapture et commutation photoinduite

A templating motif involving a 31-member macrocycle integrating a bis(2,6-diamidopyridine) / Hamilton-type receptor aided [2]rotaxane sythesis, via a copper(I)catalyzed Huisgen reaction, in the presence of a designer barbiturate or by functionalizationusing an active template synthesis. Homologous supramolecular structures were madephotochemically-active, harnessing Hamilton receptors incorporating photodimerizable 9-anthracene groups. Photodimerization and retrodimerisation of these receptors in the presence of a barbiturate thread bearing terminal bulky stopper groups permitted rotaxane assembly /disassembly. The 9-anthracene units serve as stoppers in the formation of a [2]rotaxanecompound comprising a smaller dibenzo-24-crown-8 ring. Photoirradiation of these photoactive stoppers results in an unusual all-optical topological rotaxane - catenaneinterconversion. Two approaches to photoregulate remote molecular machines byintermolecular chemical communication involving a photoguided molecule or by photoinduced electron transfer aided by reversible electronic energy transfer are considered.L’implémentation d’un agent structurant impliquant un macrocycle à 31membres et intégrant un récepteur de type Hamilton / bis(2,6-diamidopyridine) a permis deconcevoir des [2]rotaxanes via une réaction click catalysée par du cuivre(I), soit à partir d’unpseudorotaxane en présence d’un barbiturique fonctionnalisé, soit par une méthode de« gabarit actif ». Ces structures supramoléculaires ont été rendues photochimiquement activesen exploitant des analogues de récepteurs Hamilton incorporant des groupementsphotodimérisables de type 9-anthracène. La photodimérisation et la retrodimérisation de cesrécepteurs en présence d’un fil barbiturique comportant des groupements terminauxencombrants (bouchons) permettent l’assemblage et le désassemblage de rotaxanes via unprocessus de photocapture. Ces unités 9-anthracène jouent également le rôle de bouchonsphotoactifs dans la formation d’un [2]rotaxane composé d’un plus petit anneau de typedibenzo-24-couronne-8, dont la photoirradiation résulte en une interconversion topologiqueinhabituelle entre un rotaxane et un caténane. Deux approches photochimiques ont permis deréguler des machines moléculaires distantes par une communication chimiqueintermoléculaire, c’est à dire soit par un transfert de molécule photoguidée, soit par untransfert d’électron photoinduit exalté par la présence d’un transfert d’énergie électroniqueréversible

Pharmacokinetics of baricitinib in critically ill COVID-19 patients

International audienceBackground: The use of the selective Janus Kinase 1/2 inhibitor baricitinib has shown a survival benefit in mechanically ventilated COVID-19 patients but this is not without adverse drug reactions. Although critically ill patients are at risk of altered drug exposure, data on baricitinib pharmacokinetics (PK) are scarce. This study describes real-life baricitinib plasma exposure in critically ill COVID-19 patients.Methods: This retrospective observational study was conducted in critically ill patients with COVID-19 treated with baricitinib 4 mg/day. Plasma concentrations were measured at predose (C0), 1 h (C1) and 3 h (C3) after the drug intake. PK and area under the curve (AUC) were estimated using non-compartmental pharmacokinetic analysis.Results: Seven patients contributed to 22 baricitinib plasma concentration measurements after a median [range] of 3 days [2-3] of treatment. Median baricitinib plasma concentrations were 2.2 ng/mL [1.4-8.0], 24.0 ng/mL [4.9-37.3] and 14.1 ng/mL [8.3-15.1] for trough (C0), C1 and C3 concentrations respectively. The median AUC 0-24 h was 188.8 ng.h/mL [141.3-236.3]. No difference was observed in C0 and C1 when comparing patients according to body mass index 30. The patient with the lowest glomerular filtration rate (74 mL/min) had the highest baricitinib trough concentration. Overall, 2 patients had liver function test perturbation and both of them had atypical PK with delayed time to reach maximum concentration.Conclusion: High inter-patient variability and relatively low baricitinib trough concentrations and AUC were observed in critically ill COVID-19 patients receiving the usual dosage of 4 mg/day. This preliminary study encourages further exploration of the concentration-effect relationship of baricitinib in this clinical context

A prototype reversible polymersome-stabilized H2S photoejector operating under pseudophysiological conditions

Persistent self-assembled polymersome capsules are shown to solubilise and stabilize a new hydrosulfide-containing (2), as well as hydroxylated (1), malachite green derivatives in their leuco-forms in aqueous buffer solution. Photoirradiation resulted in reversible hydroxide release/hydrogen sulfide generation. Notably, the efficient augmentation of H2S concentration to physiologically-relevant levels is shown

Selective and Cooperative Photocycloadditions within Multistranded Aromatic Sheets

International audienceA series of aromatic helix-sheet-helix oligoamide foldamers composed of several different photosensitive diazaanthracene units have been designed and synthesized. Molecular objects up to 7 kDa were straightforwardly produced on a 100 mg scale. NMR and crystallographic investigations revealed that helix-sheet-helix architectures can adopt one or two distinct conformations. Sequences composed of an even number of turn units were found to fold in a canonical symmetrical conformation with two helices of identical handedness stacked above and below the sheet segment. Sequences composed of an odd number of turns revealed a coexistence between a canonical fold with helices of opposite handedness, and an alternate fold with a twist within the sheet and two helices of identical handedness. The proportions between these species could be manipulated, in some cases quantitatively, being dependent on solvent, temperature and absolute control of helix handedness. Diazaanthracene units were shown to display distinct reactivity towards 4+4 photocycloadditions according to the substituent in the 9 position. Their organization within the sequences was programmed to allow photoreactions to take place in a specific order. Reaction pathways and kinetics were deciphered and products characterized, demonstrating the possibility to orchestrate successive photoreactions so as to avoid orphan units, or to deliberately produce orphan units at precise locations. Strong cooperative effects were observed in which the photoreaction rate was influenced by the presence (or absence) of photoadducts in the structure. Multiple photoreactions within the aromatic sheet eventually lead to the structure lengthening and stiffening, locking conformational equilibria. Photoproducts could be thermally reverted

Reactivity of a Zn(Cys)2(His)2 Zinc Finger with Singlet Oxygen: Oxidation Directed toward Cysteines but not Histidines

International audienceSinglet oxygen ((1) O2 ) is an important reactive oxygen species in biology that has deleterious effects. Proteins constitute the main target of (1) O2 in cells. Several organisms are able to mount a transcriptional defense against (1) O2 . ChrR and MBS are two proteins with Zn(Cys)2 (His)2 zinc finger sites that are involved in the regulation of the defense against (1) O2 . In this article, we investigate the reactivity of ZnCPF, a Zn(Cys)2 (His)2 classical betabetaalpha zinc finger, with (1) O2 . We show that ZnCPF interacts with (1) O2 mainly by physical quenching using a combination of (1) O2 luminescence quenching and kinetic competition experiments. The chemical reaction, which accounts for 5% of the interaction, leads to oxidation of cysteines but not histidines. Primary photooxidation products, identified by HPLC and mass spectrometry, are sulfinate (75±5%) and disulfides (25±5%). The peptides that have a single cysteine thiolate oxidized into a sulfinate are still able to bind one equivalent Zn(2+) but with a dramatic reduction of the binding constant compared to ZnCPF despite the preservation of the betabetaalpha fold, as shown by NMR and CD titrations. Finally, ZnCPF is compared to ZnLTC , a treble clef Zn(Cys)4 zinc finger, to gain further insight into the behavior of zinc fingers toward (1) O2

Heat Engine Drives Transport of an FeII 4 L4 Cage and Cargo.

The directed motion of species against a chemical potential gradient is a fundamental feature of living systems, underpinning processes that range from transport through cell membranes to neurotransmission. The development of artificial active cargo transport could enable new modes of chemical purification and pumping. Here, a heat engine is described that drives chemical cargo between liquid phases to generate a concentration gradient. The heat engine, composed of a functionalized FeII 4 L4 coordination cage, is grafted with oligoethylene glycol imidazolium chains. These chains undergo a conformational change upon heating, causing the cage and its cargo to reversibly transfer between aqueous and organic phases. Furthermore, sectional heating and cooling allow for the cage to traverse multiple phase boundaries, allowing for longer-distance transport than would be possible using a single pair of phases