Oxidative Neutralisation of Sulfur-based Chemical Warfare Agents Mediated by a Lipase: from Batch to Flow Reactor.

The sulfur-containing chemical warfare agents sulfur mustard HD and nerve agent VX are highly toxic and persistent in the environment. Therefore, their neutralisation requires harsh oxidation conditions, but also precise selectivity. Here we report the safe and effective detoxification of surrogates CEES and PhX by selective oxidation of the sulfur atom by generating peracetic acid from AcOEt and aq.

Fluorogenic detection of cyanide ions in pure aqueous media through an intramolecular crossed-benzoin reaction: limitations unveiled and possible solutions.

Reaction-based fluorogenic sensing of lethal cyanide anions in aqueous matrices remains a big challenge. We have revisited the reported approach about an intramolecular crossed-benzoin reaction leading to the release of a phenol-based fluorophore. Fluorescence assays and RP-HPLC-MS analyses have helped us to highlight its limitations related to poor aqueous stability of probes and impossibility to achieve molecular amplification despite the assumed catalytic activation mechanism.

Light-Induced Unlocking Reactivity of Fragments for Fast Target-Guided Synthesis of Carbonic Anhydrase Inhibitors.

We showcase the successful combination of photochemistry and kinetic target-guided synthesis (KTGS) for rapidly pinpointing enzyme inhibitors. KTGS is a fragment-based drug discovery (FBDD) methodology in which the biological target (BT) orchestrates the construction of its own ligand from fragments featuring complementary reactive functionalities. Notably, fragments interacting with the protein binding sites leverage their spatial proximity, facilitating a preferential reaction.

A Photoredox Thiol-yne Reaction for the Synthesis of Vinyl Sulfide-Based Coumarins and its Effect on Fluorescence Properties.

Coumarins still remain one of the most widely explored fluorescent dyes, with a broad spectrum of applications spanning various fields, such as molecular imaging, bioorganic chemistry, materials chemistry, or medical sciences. Their fluorescence is strongly based on a push-pull mechanism involving an electron-donating group (EDG), mainly located at the C7 or C8 positions of the dye core. Unfortunately, up to now, these positions have been very limited to hydroxyl or amino groups.

Detoxification of V-Nerve Agents Assisted by a Microperoxidase: New Pathway Revealed by the Use of a Relevant VX Simulant.

The biocatalyzed oxidative detoxification of the V-series simulant PhX, by mean of the microperoxidase AcMP11, affords the corresponding phosphonothioate as the prominent product instead of the classical P-S and P-O bond cleavage. While PhX is structurally very close to the live agent VX (the methyl group is replaced by a phenyl), assessment with other surrogates missing the nucleophilic amino function displayed more resistance under the same conditions with no phosphonothioate observed. These encouraging results highlight 1) the efficacy of AcMP11 microperoxidase to efficiently detoxify V-series organophosphorus nerve agents (OPNA), and 2) the necessity to use representative alkyl or aryl phosphonothioates simulants such as PhX bearing the appropriate side chain as well as the P-O and P-S cleavable bond to mimic accurately the V-series OPNA to prevent false positive or false negative results.

Do Not Waste Time─Ensure Success in Your Cross-Linking Mass Spectrometry Experiments before You Begin.

Cross-linking mass spectrometry (XL-MS) has become a very useful tool for studying protein complexes and interactions in living systems. It enables the investigation of many large and dynamic assemblies in their native state, providing an unbiased view of their protein interactions and restraints for integrative modeling. More researchers are turning toward trying XL-MS to probe their complexes of interest, especially in their native environments.

Biological response and cell death signaling pathways modulated by tetrahydroisoquinoline-based aldoximes in human cells.

The uncharged 3-hydroxy-2-pyridine aldoximes with protonatable tertiary amines are studied as antidotes in toxic organophosphates (OP) poisoning. Due to some of their specific structural features, we hypothesize that these compounds could exert diverse biological activity beyond their main scope of application. To examine this further, we performed an extensive cell-based assessment to determine their effects on human cells (SH-SY5Y, HEK293, HepG2, HK-2, myoblasts and myotubes) and possible mechanism of action.

Metalloenzyme-Mediated Thiol-Yne Addition Towards Photoisomerizable Fluorescent Dyes.

Proteins are able to irreversibly assemble biologically active ligands from building blocks bearing complementary reactive functions due their spatial proximity, through a kinetic target-guided synthetic process (also named in situ click chemistry). Although linkages thus formed are mostly passive, some of them have shown to significantly contribute to the protein binding through for instance hydrogen bonding and stacking interactions. Biocompatible reactions and click chemistry are a formidable source of inspiration for developing such new protein-directed ligations.

A New Class of Bi- and Trifunctional Sugar Oximes as Antidotes against Organophosphorus Poisoning.

Recent events demonstrated that organophosphorus nerve agents are a serious threat for civilian and military populations. The current therapy includes a pyridinium aldoxime reactivator to restore the enzymatic activity of acetylcholinesterase located in the central nervous system and neuro-muscular junctions. One major drawback of these charged acetylcholinesterase reactivators is their poor ability to cross the blood-brain barrier.

3-Benzoylquinoxalinone as a photoaffinity labelling derivative with fluorogenic properties allowing reaction monitoring under "no-wash" conditions.

Described herein is a quinoxalinone-based photoaffinity probe with caged fluorescence properties. Upon visible blue LED irradiation (λ 450 nm), this photo-crosslinker is able to covalently capture proteins with concomitant fluorescence labelling. This process enables monitoring applications under "no wash" conditions.

Discovery of a Potent Dual Inhibitor of Acetylcholinesterase and Butyrylcholinesterase with Antioxidant Activity that Alleviates Alzheimer-like Pathology in Old APP/PS1 Mice.

The combination of the scaffolds of the cholinesterase inhibitor huprine Y and the antioxidant capsaicin results in compounds with nanomolar potencies toward human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) that retain or improve the antioxidant properties of capsaicin. Crystal structures of their complexes with AChE and BChE revealed the molecular basis for their high potency. Brain penetration was confirmed by biodistribution studies in C57BL6 mice, with one compound () displaying better brain/plasma ratio than donepezil.

Tailored Bioorthogonal and Bioconjugate Chemistry: A Source of Inspiration for Developing Kinetic Target-Guided Synthesis Strategies.

Kinetic target-guided synthesis (KTGS) is a promising tool for the discovery of biologically active compounds. It relies on the identification of potent ligands that are covalently assembled by the biological targets themselves from a pool of reagents. Significant effort is devoted to developing new KTGS strategies; however, only a handful of biocompatible reactions are available, which may be insufficient to meet the specificities (stability, dynamics, active site topology, etc.

Mono- and Poly-unsaturated Phosphatidic Acid Regulate Distinct Steps of Regulated Exocytosis in Neuroendocrine Cells.

Specific forms of fatty acids are well known to have beneficial health effects, but their precise mechanism of action remains elusive. Phosphatidic acid (PA) produced by phospholipase D1 (PLD1) regulates the sequential stages underlying secretory granule exocytosis in neuroendocrine chromaffin cells, as revealed by pharmacological approaches and genetic mouse models. Lipidomic analysis shows that secretory granule and plasma membranes display distinct and specific composition in PA.

Functional characterization of multifunctional ligands targeting acetylcholinesterase and alpha 7 nicotinic acetylcholine receptor.

Alzheimer's disease (AD) is a neurodegenerative disorder associated with cholinergic dysfunction, provoking memory loss and cognitive dysfunction in elderly patients. The cholinergic hypothesis provided over the years with molecular targets for developing palliative treatments for AD, acting on the cholinergic system, namely, acetylcholinesterase and α7 nicotinic acetylcholine receptor (α7 nAChR). In our synthetic work, we used "click-chemistry" to synthesize two Multi Target Directed Ligands (MTDLs) MB105 and MB118 carrying tacrine and quinuclidine scaffolds which are known for their anticholinesterase and α7 nAChR agonist activities, respectively.

Fluorophore-Assisted Click Chemistry through Copper(I) Complexation.

The copper-catalyzed alkyne-azide cycloaddition (CuAAC) is one of the most powerful chemical strategies for selective fluorescent labeling of biomolecules in in vitro or biological systems. In order to accelerate the ligation process and ensure efficient formation of conjugates under diluted conditions, external copper(I) ligands or sophisticated copper(I)-chelating azides are used. This latter strategy, however, increases the bulkiness of the triazole linkage, thus perturbing the biological function or dynamic behavior of the conjugates.

Chromogranin A preferential interaction with Golgi phosphatidic acid induces membrane deformation and contributes to secretory granule biogenesis.

Chromogranin A (CgA) is a key luminal actor of secretory granule biogenesis at the trans-Golgi network (TGN) level but the molecular mechanisms involved remain obscure. Here, we investigated the possibility that CgA acts synergistically with specific membrane lipids to trigger secretory granule formation. We show that CgA preferentially interacts with the anionic glycerophospholipid phosphatidic acid (PA).

Maleimide-based metal-free ligation with dienes: a comparative study.

A brief literature survey reveals that metal-free ligation such as the maleimide-based cycloaddition with electron-rich (hetero)dienes is a widespread tool for the assembly of (bio)molecular systems with applications in biotechnology, materials science, polymers and bio-organic chemistry. Despite their everyday use, only scattered data about their kinetics as well as the stabilities of corresponding products under physiological conditions, are accessible. These key parameters are yet, of paramount importance to ensure the rapid and effective preparation of stable compounds.

Pharmacokinetic Evaluation of Brain Penetrating Morpholine-3-hydroxy-2-pyridine Oxime as an Antidote for Nerve Agent Poisoning.

Nerve agents, the deadliest chemical warfare agents, are potent inhibitors of acetylcholinesterase (AChE) and cause rapid cholinergic crisis with serious symptoms of poisoning. Oxime reactivators of AChE are used in medical practice in the treatment of nerve agent poisoning, but the search for novel improved reactivators with central activity is an ongoing pursuit. For numerous oximes synthesized, reactivation is a standard approach in biological evaluation with little attention given to the pharmacokinetic properties of the compounds.

Diverted Natural Lossen-type Rearrangement for Bioconjugation through in Situ Myrosinase-Triggered Isothiocyanate Synthesis.

Fluorescein isothiocyanate (FITC) is one of the most extensively used fluorescent probes for the labeling of biomolecules. The isothiocyanate function reacts with lysine residues of proteins to provide a chemically stable thiourea linkage without releasing any byproduct. However, diversification of isothiocyanate-based reagents is still hampered by the lack of mild conditions to generate isothiocyanate chemical functions, as well as by their poor stability and limited solutions available to increase water solubility, restricting the use of isothiocyanate labeling to highly water-soluble fluorophores.

Design, biological evaluation and X-ray crystallography of nanomolar multifunctional ligands targeting simultaneously acetylcholinesterase and glycogen synthase kinase-3.

Both cholinesterases (AChE and BChE) and kinases, such as GSK-3α/β, are associated with the pathology of Alzheimer's disease. Two scaffolds, targeting AChE (tacrine) and GSK-3α/β (valmerin) simultaneously, were assembled, using copper(I)-catalysed azide alkyne cycloaddition (CuAAC), to generate a new series of multifunctional ligands. A series of eight multi-target directed ligands (MTDLs) was synthesized and evaluated in vitro and in cell cultures.

Real-time molecular optical micro-imaging of EGFR mutations using a fluorescent erlotinib based tracer.

Background: EGFR mutations are routinely explored in lung adenocarcinoma by sequencing tumoral DNA. The aim of this study was to evaluate a fluorescent-labelled erlotinib based theranostic agent for the molecular imaging of mutated EGFR tumours in vitro and ex vivo using a mice xenograft model and fibred confocal fluorescence microscopy (FCFM).

Methods: The fluorescent tracer was synthesized in our laboratory by addition of fluorescein to an erlotinib molecule.

Investigation of tetrazine reactivity towards C-nucleophiles: pyrazolone-based modification of biomolecules.

Chemoselective, biocompatible ligation reactions are the key components for efficient and modular access to biomolecular scaffolds. Tetrazine ligation leads to the formation of a mixture of isomers, which makes reaction monitoring, purification and characterization of conjugates difficult. We report herein a modified tetrazine ligation strategy based on the use of a pyrazolone coupling partner, which provides a single molecule conjugate.

Combination delivery of two oxime-loaded lipid nanoparticles: Time-dependent additive action for prolonged rat brain protection.

A novel approach for brain protection against poisoning by organophosphorus agents is developed based on the combination treatment of dual delivery of two oximes. Pralidoxime chloride (2-PAM) and a novel reactivator, 6-(5-(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)pentyl)-3-hydroxy picolinaldehyde oxime (3-HPA), have been loaded in solid-lipid nanoparticles (SLNs) to offer distinct release profile and systemic half-life for both oximes. To increase the therapeutic time window of both oximes, SLNs with two different compartments were designed to load each respective drug.

Use of an Air-Stable Cu(I)-NHC Catalyst for the Synthesis of Peptidotriazoles.

We report the use of air-stable Cu(I)-NHC complex 4a as a catalyst for the efficient microwave-assisted synthesis of peptidotriazoles on solid phase. Compared with the usual conditions (CuI or CuSO/NaAsc), catalyst 4a allowed the preparation of a series of peptidomimetic compounds containing a 1,2,3-triazole ring in their backbone without the oxidation of common side-chains. Overall, the peptidotriazoles were obtained in good yields (61-87%), in excellent purity (higher than 94%) and with low copper contamination.

Structure-Based Optimization of Nonquaternary Reactivators of Acetylcholinesterase Inhibited by Organophosphorus Nerve Agents.

Acetylcholinesterase (AChE), a key enzyme in the central and peripheral nervous systems, is the principal target of organophosphorus nerve agents. Quaternary oximes can regenerate AChE activity by displacing the phosphyl group of the nerve agent from the active site, but they are poorly distributed in the central nervous system. A promising reactivator based on tetrahydroacridine linked to a nonquaternary oxime is also an undesired submicromolar reversible inhibitor of AChE.