Determination of tissue distribution of VX and its metabolites EMPA and EA-2192 in various rat tissues by LC-ESI-MS/MS after phosphotriesterase treatment.

Phosphotriesterases (PTE) are a new and promising approach for the treatment of organophosphate poisoning, since the current therapy of such intoxications shows some limitations. A previous rat in vivo study confirmed the therapeutic effect of PTE, which were specifically designed for VX breakdown, and demonstrated rapid degradation of VX in whole blood samples. The present study now focuses on the degradation of VX and its distribution in organ tissues of the animals used in the aforementioned study.

Toxicokinetic analysis of the highly toxic nerve agent VX in commercially available multi-organ-chips - Ways to overcome compound absorption.

Organ-on-a-chip technology is considered a next-generation platform in pharmacology and toxicology. Nevertheless, this novel technology still faces several challenges concerning the respective materials which are used for these microfluidic devices. Currently available organ-chips are most often based on polydimethylsiloxane (PDMS).

Post-VX exposure treatment of rats with engineered phosphotriesterases.

The biologically stable and highly toxic organophosphorus nerve agent (OP) VX poses a major health threat. Standard medical therapy, consisting of reactivators and competitive muscarinic receptor antagonists, is insufficient. Recently, two engineered mutants of the Brevundimonas diminuta phosphotriesterase (PTE) with enhanced catalytic efficiency (k/K = 21 to 38 × 10 M min) towards VX and a preferential hydrolysis of the more toxic P(-) enantiomer were described: PTE-C23(R152E)-PAS(100)-10-2-C3(I106A/C59V/C227V/E71K)-PAS(200) (PTE-2), a single-chain bispecific enzyme with a PAS linker and tag having enlarged substrate spectrum, and 10-2-C3(C59V/C227V)-PAS(200) (PTE-3), a stabilized homodimeric enzyme with a double PASylation tag (PAS-tag) to reduce plasma clearance.

Release of protein-bound nerve agents by excess fluoride from whole blood: GC-MS/MS method development, validation, and application to a real-life denatured blood sample.

In analogy to the fluoride-induced regeneration of butyrylcholinesterase (BChE) inhibited by nerve agents a method was developed and optimized for whole blood samples. Compared to the plasma method, regeneration grade was found to be higher for cyclosarin (GF), i-butylsarin from VR, and n-butylsarin from CVX, but lower for sarin (GB), fluorotabun from tabun (GA), and ethylsarin from VX. Regeneration grade of soman (GD) is the same for both matrices because it is released from serum albumin and not from cholinesterases.

Catalytic activity and stereoselectivity of engineered phosphotriesterases towards structurally different nerve agents in vitro.

Highly toxic organophosphorus nerve agents, especially the extremely stable and persistent V-type agents such as VX, still pose a threat to the human population and require effective medical countermeasures. Engineered mutants of the Brevundimonas diminuta phosphotriesterase (BdPTE) exhibit enhanced catalytic activities and have demonstrated detoxification in animal models, however, substrate specificity and fast plasma clearance limit their medical applicability. To allow better assessment of their substrate profiles, we have thoroughly investigated the catalytic efficacies of five BdPTE mutants with 17 different nerve agents using an AChE inhibition assay.

In Vitro Interaction of Organophosphono- and Organophosphorothioates with Human Acetylcholinesterase.

The implementation of the Chemical Weapons Convention (CWC) in 1997 was a milestone in the prohibition of chemical warfare agents (CWA). Yet, the repeated use of CWA underlines the ongoing threat to the population. Organophosphorus (OP) nerve agents still represent the most toxic CWA subgroup.

Influence of cyclic and acyclic cucurbiturils on the degradation pathways of the chemical warfare agent VX.

The highly toxic nerve agent VX is a methylphosphonothioate that degrades via three pathways in aqueous solution, namely through the hydrolysis of the P-O or P-S bonds, or the cleavage of the C-S bond at the 2-aminoethyl residue. In the latter case, an aziridinium ion and a phosphonothioate is formed. Here it is shown that acyclic or cyclic cucurbiturils inhibit these reactions in phosphate buffer at physiological pH and thus stabilise the nerve agent.

Screening of chiral shift reagents suitable to generically separate the enantiomers of V-agents by P-NMR spectroscopy.

Fourteen amino acids protected at the N-terminal and at their side chains were screened for resolving the enantiomers of V-agents by NMR. While none of the shift reagents tested showed really effective separation in proton NMR, two of them (BOC-Gln(Xan)-OH, 16, and Z-Arg(Z)-OH), 21, with 16 superior to 21) were found suitable to separate the enantiomers of all V-agent homologues involved in the test by P-NMR. Molar ratios investigated were 1:0.

Forensic evidence of sulfur mustard exposure in real cases of human poisoning by detection of diverse albumin-derived protein adducts.

We present the forensic analyses of plasma samples of human victims exposed to sulfur mustard (SM) in a crisis region in the Middle East in 2015. A few hours after exposure, poisoned persons showed typical signs and symptoms of percutaneous SM exposure including erythema and later on blisters and hardly healing skin wounds. Blood samples were collected 15 days after poisoning to be analyzed for the presence of long-lived protein-adduct biomarkers to verify SM poisoning.

Fatal sarin poisoning in Syria 2013: forensic verification within an international laboratory network.

During the United Nations fact-finding mission to investigate the alleged use of chemical warfare agents in the Syrian Arab Republic in 2013, numerous tissues from a deceased female victim, who had displayed symptoms of cholinergic crisis, were collected. The Organisation for the Prohibition of Chemical Weapons (OPCW) authorized two specialized laboratories in the Netherlands and Germany for forensic analysis of these samples. Diverse modern mass spectrometry (MS)-based procedures in combination with either liquid chromatography (LC) or gas chromatography (GC) separation were applied.

Detoxification of VX and Other V-Type Nerve Agents in Water at 37 °C and pH 7.4 by Substituted Sulfonatocalix[4]arenes.

Sulfonatocalix[4]arenes with an appended hydroxamic acid residue can detoxify VX and related V-type neurotoxic organophosphonates with half-lives down to 3 min in aqueous buffer at 37 °C and pH 7.4. The detoxification activity is attributed to the millimolar affinity of the calixarene moiety for the positively charged organophosphonates in combination with the correct arrangement of the hydroxamic acid group.

Single treatment of VX poisoned guinea pigs with the phosphotriesterase mutant C23AL: Intraosseous versus intravenous injection.

The recent attacks with the nerve agent sarin in Syria reveal the necessity of effective countermeasures against highly toxic organophosphorus compounds. Multiple studies provide evidence that a rapid onset of antidotal therapy might be life-saving but current standard antidotal protocols comprising reactivators and competitive muscarinic antagonists show a limited efficacy for several nerve agents. We here set out to test the newly developed phosphotriesterase (PTE) mutant C23AL by intravenous (i.

Toxicology of organophosphorus compounds in view of an increasing terrorist threat.

The implementation of the Chemical Weapon Convention (CWC), prohibiting the development, production, storage and use of chemical weapons by 192 nations and the ban of highly toxic OP pesticides, especially class I pesticides according to the WHO classification, by many countries constitutes a great success of the international community. However, the increased interest of terrorist groups in toxic chemicals and chemical warfare agents presents new challenges to our societies. Almost seven decades of research on organophosphorus compound (OP) toxicology was mainly focused on a small number of OP nerve agents despite the fact that a huge number of OP analogues, many of these agents having comparable toxicity to classical nerve agents, were synthesized and published.

Reactivation of nerve agent-inhibited human acetylcholinesterase by obidoxime, HI-6 and obidoxime+HI-6: Kinetic in vitro study with simulated nerve agent toxicokinetics and oxime pharmacokinetics.

Despite extensive research for decades no effective broad-spectrum oxime for the treatment of poisoning by a broad range of nerve agents is available. Previous in vitro and in vivo data indicate that the combination of in service oximes could be beneficial. To investigate the ability of obidoxime, HI-6 and the combination of both oximes to reactivate inhibited human AChE in the presence of sarin, cyclosarin or tabun we adopted a dynamic in vitro model with real-time and continuous determination of AChE activity to simulate inhalation nerve agent exposure and intramuscular oxime administration.

Application of a dynamic in vitro model with real-time determination of acetylcholinesterase activity for the investigation of tabun analogues and oximes.

Tabun-inhibited acetylcholinesterase (AChE) is rather resistant towards reactivation by oximes in vitro while in vivo experiments showed some protection of animals poisoned by this chemical warfare nerve agent after treatment with an oxime and atropine. In addition, AChE inhibited by close tabun analogues, N,N-diethyltabun and N,N-di-n-propyltabun was completely resistant towards reactivation by oximes. In order to get more insight into potential mechanisms of this oxime resistance experiments with these toxic agents and the oximes obidoxime, 2-PAM, MMB-4 and HI-6 were performed utilizing a dynamic model with real-time determination of AChE activity.

Medical documentation, bioanalytical evidence of an accidental human exposure to sulfur mustard and general therapy recommendations.

Sulfur mustard (SM) is a chemical warfare agent (CWA) that was first used in World War I and in several military conflicts afterwards. The threat by SM is still present even today due to remaining stockpiles, old and abandoned remainders all over the world as well as to its ease of synthesis. CWA are banned by the Chemical Weapons Convention (CWC) interdicting their development, production, transport, stockpiling and use and are subjected to controlled destruction.

Detoxification of organophosphorus pesticides and nerve agents through RSDL: efficacy evaluation by (31)P NMR spectroscopy.

Intoxication by organophosphorus compounds, especially by pesticides, poses a considerable risk to the affected individual. Countermeasures involve both medical intervention by means of antidotes as well as external decontamination to reduce the risk of dermal absorption. One of the few decontamination options available is Reactive Skin Decontamination Lotion (RSDL), which was originally developed for military use.

Reactions of methylphosphonic difluoride with human acetylcholinesterase and oximes--Possible therapeutic implications.

Highly toxic organophosphorus (OP) nerve agents are well characterized regarding chemical, biological and toxicological properties and the effectiveness of standard atropine and oxime therapy. Open literature data on the key nerve agent precursor methylphosphonic difluoride (DF) are scarce. To fill this gap the reactions of DF and its main degradation product methylphosphonofluoridic acid (MF) with human acetylcholinesterase (AChE) and the oximes obidoxime, HI-6 and 2-PAM were investigated in vitro.

In vitro toxicokinetic studies of cyclosarin: molecular mechanisms of elimination.

The toxicokinetics of in vitro elimination of highly toxic cyclosarin (GF) in biological systems revealed striking stereoselective differences in the range of 0.01μM to 1mM GF. While weak concentration dependency was detected for elimination of the toxic (-)-enantiomer indicating catalytic processes, elimination of less toxic (+)-GF followed unusual kinetics with relatively high concentration dependency.

Tabun scavengers based on hydroxamic acid containing cyclodextrins.

Arrangement of several hydroxamic acid-derived substituents along the cavity of a cyclodextrin ring leads to compounds that detoxify tabun in TRIS-HCl buffer at physiological pH and 37.0 °C with half-times as low as 3 min.

Structural requirements for effective oximes--evaluation of kinetic in vitro data with phosphylated human AChE and structurally different oximes.

Treatment of poisoning by various organophosphorus (OP) nerve agents with established acetylcholinesterase (AChE) reactivators (oximes) is insufficient. In consequence, extensive research programs have been undertaken in various countries in the past decades to identify more effective oximes. The efficacy of new compounds has been investigated with different in vitro and in vivo models which hamper the comparison of results from different laboratories.

Reactivation kinetics of a series of related bispyridinium oximes with organophosphate-inhibited human acetylcholinesterase--Structure-activity relationships.

Despite extensive research in the last six decades, oximes are the only available drugs which enable a causal treatment of poisoning by organophosphorus compounds (OP). However, numerous in vitro and in vivo studies demonstrated a limited ability of these oximes to reactivate acetylcholinesterase (AChE) inhibited by different OP pesticides and nerve agents. New oximes were mostly tested for their therapeutic efficacy by using different animal models and for their reactivating potency with AChE from different species.

Kinetic interactions of a homologous series of bispyridinium monooximes (HGG oximes) with native and phosphonylated human acetylcholinesterase.

Inhibition of acetylcholinesterase (AChE) is the main toxic mechanism of organophosphorus compounds (OP) and reactivation of OP-inhibited AChE by oximes is a mainstay of antidotal treatment. The inadequate efficacy of clinically used oximes led to the synthesis of numerous new compounds in the past decades to identify more effective reactivators. Despite of extensive in vitro reactivation studies the structural features for the development of effective oximes are not well understood.

Purity of antidotal oxime HI-6 DMS as an active pharmaceutical ingredient for auto-injectors and infusions.

As reactivators of inhibited acetylcholinesterase, oximes are essential antidotes in poisoning by organophosphorus compounds. Due to its superior efficacy in cases of soman, cyclosarin, and sarin poisoning, the oxime HI-6 represents a promising option for an active pharmaceutical ingredient (API) in the further development of antidote therapy for nerve agent poisoning. Developmental lots of HI-6 DMS (dimethanesulfonate) provided by different manufacturers were examined with respect to their content and purity with a view to their future use as an API.