Chemical forensic profiling and attribution signature determination of sarin nerve agent using GC-MS, LC-MS and NMR.

Sarin is a highly toxic nerve agent classified by the Chemical Weapon Convention as a Schedule 1 chemical with no use other than to kill or injure. Moreover, in recent times, chemical warfare agents have been deployed against both military and civilian populations. Chemical warfare agents always contain minor impurities that can provide important chemical attribution signatures (CAS) that can aid in forensic investigations. In order to understand the trace molecular composition of sarin, various analytical approaches including GC-MS, LC-MS and NMR were used to determine the chemical markers of a set of sarin samples. Precursor materials were studied and the full characterisation of a synthetic process was undertaken in order to provide new insights into potential chemical attribution signatures for this agent. Several compounds that were identified in the precursor were also found in the sarin samples linking it to its method of preparation. The identification of these CAS contributes critical information about a synthetic route to sarin, and has potential for translation to related nerve agents.

2-Morpholinoisoflav-3-enes as flexible intermediates in the synthesis of phenoxodiol, isophenoxodiol, equol and analogues: vasorelaxant properties, estrogen receptor binding and Rho/RhoA kinase pathway inhibition.

Isoflavone consumption correlates with reduced rates of cardiovascular disease. Epidemiological studies and clinical data provide evidence that isoflavone metabolites, such as the isoflavan equol, contribute to these beneficial effects. In this study we developed a new route to isoflavans and isoflavenes via 2-morpholinoisoflavenes derived from a condensation reaction of phenylacetaldehydes, salicylaldehydes and morpholine. We report the synthesis of the isoflavans equol and deoxygenated analogues, and the isoflavenes 7,4'-dihydroxyisoflav-3-ene (phenoxodiol, haganin E) and 7,4'-dihydroxyisoflav-2-ene (isophenoxodiol). Vascular pharmacology studies reveal that all oxygenated isoflavans and isoflavenes can attenuate phenylephrine-induced vasoconstriction, which was unaffected by the estrogen receptor antagonist ICI 182,780. Furthermore, the compounds inhibited U46619 (a thromboxane A(2) analogue) induced vasoconstriction in endothelium-denuded rat aortae, and reduced the formation of GTP RhoA, with the effects being greatest for equol and phenoxodiol. Ligand displacement studies of rat uterine cytosol estrogen receptor revealed the compounds to be generally weak binders. These data are consistent with the vasorelaxation activity of equol and phenoxodiol deriving at least in part by inhibition of the RhoA/Rho-kinase pathway, and along with the limited estrogen receptor affinity supports a role for equol and phenoxodiol as useful agents for maintaining cardiovascular function with limited estrogenic effects.

Stereoselective total synthesis of (-)-spirofungin†A by utilising hydrogen-bond controlled spiroketalisation.

The stereoselective total synthesis of the spiroketal containing Streptomyces metabolite (-)-spirofungin A (1) is described. A key step involved a spiroketalisation controlled by an intramolecular H-bond which favoured the desired spiroketal 4 (13:1 ratio). The presence of the intramolecular H-bond in 4 is possibly due to a 1,5-alkyne-oxygen interaction. Other key steps include an efficient cross-metathesis to form the spiroketal precursor, a tin mediated syn-aldol reaction and a Stille cross-coupling reaction to create the C22C23 bond. A final Wittig extension followed by deprotection gave (-)-spirofungin A (1).

Investigating the chemical impurity profiles of fentanyl preparations and precursors to identify chemical attribution signatures for synthetic method attribution.

From an analytical chemistry standpoint, determining the chemical attribution signatures (CAS) of synthetic reaction mixtures is an impurity profiling exercise. Identifying and understanding the impurity profile and CAS of these chemical agents would allow them to be exploited for chemical forensic information, such as how a particular chemical agent was synthesised. Being able to determine the synthetic route used to make a chemical agent allows for the possibility of batches of the agent, and individual incidents using that agent, to be forensically linked. This information is of particular benefit to agencies investigating the nefarious and illicit use of chemical agents. One such chemical agent of interest to law enforcement and national security agencies is fentanyl. In this study two acylation methods for the final step of fentanyl production, herein termed the Janssen and Siegfried methods, were investigated by liquid chromatography- high resolution mass spectrometry (LC-HRMS) and multivariate statistical analysis (MVA). From these data, fifty-five chemical impurities were identified. Of these, ten were specific CAS for the Janssen method, and five for the Siegfried method. Additionally, analytical data from four different literature methods for production of the fentanyl precursor 4-anilino-N-phenethylpiperidine (ANPP), were compared to the results obtained from the method of production (Valdez) used in this study. Comparison of the LC-HRMS data for these five methods allowed for four Valdez specific impurities to be identified. These may be useful CAS for the Valdez method of ANPP production.

The identification of chemical attribution signatures of stored VX nerve agents using NMR, GC-MS, and LC-HRMS.

The organophosphorous nerve agent VX is classified by the Chemical Warfare Convention (CWC) as a Schedule 1 chemical; namely a substance that is highly toxic with no use that is of benefit to society. Even with this classification, the nefarious use of the Schedule 1 chemical VX has been observed, as demonstrated in 2017 in Malaysia. Therefore, undertaking chemical analysis on samples of VX to identify chemical attribution signatures (CAS) for chemical forensics is required. To further understand the chemical profile of VX, and to aid in the identification of potential CAS, three in house synthesised stocks of VX were investigated. The three VX stocks analysed were synthesised in 2014, 2017 and 2018 using the same method, allowing for a comparison of data between each of the stocks at different stages of storage. As opposed to a majority of literature reports, these agent stocks were not stabilised, nor were they subjected to forced degradation. Using NMR, high resolution (HR) LC-HRMS, GC-(EI)MS and GC-(CI)MS to gain a full insight into the CAS profile, a total of 44 compounds were identified. Of these compounds, 30 were readily identified through accurate mass measurement and NIST library matches. A further seven were identified through extensive LC-HRMS/MS studies, with seven remaining unresolved. Several compounds, identified in minor amounts, were able to be traced back to impurities in the precursor compounds used in the synthesis of VX, and hence may be useful as CAS for source attribution.

Synthesis and evaluation of dithiolethiones as novel cyclooxygenase inhibitors.

3H-1,2-Dithiole-3-thiones substituted with a 3,5-di-tert-butyl-4-hydroxyphenyl (DTBHP) or a 3,5-di-tert-butyl-4-methoxyphenyl group at the C5 position were prepared and their ability to inhibit the cyclooxygenase isoenzymes, COX-1 and COX-2 was evaluated. Both compounds were potent inhibitors of COX-2 (relative to rofecoxib), and while the phenol was a weak inhibitor of COX-1, the methyl ether gave no measurable inhibition. Docking studies of the two compounds into the COX-1 and -2 active sites showed that the methyl ether could only fit in the COX-2 active site whereas the phenol could be docked into both COX-1 and -2. This study reports a new mode for inhibitor binding to COX-1 and -2 and a novel structural scaffold for the development of COX-2 selective inhibitors.

'Click' cycloaddition catalysts: copper(I) and copper(II) tris(triazolylmethyl)amine complexes.

The CuI complex of the 'click' ligand tris(benzyltriazolylmethyl)amine is an unusual dinuclear dication with one triazole unit bridging two metal centers, and is an effective catalyst for the 'click' cycloaddition reaction.

Total synthesis of the proposed structure for spirofungin B: a reassignment of the stereochemistry.

[structure: see text] The total synthesis of the proposed structure for spirofungin B (2) is described. The data for the synthetic material did not compare with that for the natural product leading to the conclusion that the structure 2 assigned for spirofungin B is incorrect. Analysis of the NMR data reported for spirofungins A and B as well as related spiroketals allowed for the reassignment of the stereochemistry of spirofungin B to be that corresponding to 15-epi-spirofungin A (27).

The galanin-3 receptor antagonist, SNAP 37889, reduces operant responding for ethanol in alcohol-preferring rats.

BACKGROUND/OBJECTIVE: The galanin-3 receptor (GALR3) subtype has been identified as having a role in both feeding behaviour and the regulation of emotional states including anxiety. Despite the evidence for an association between galanin and alcohol, the current study is the first to explore the direct role of GALR3 in this context. The present study investigated the potential of the novel selective GALR3 antagonist, SNAP 37889, to reduce anxiety-like behaviour and voluntary ethanol consumption in the iP (alcohol-preferring) rat. This was achieved through a number of behavioural paradigms testing for anxiety, along with the operant self-administration model. RESULTS: Overall, male iP rats treated with SNAP 37889 at a dose of 30 mg/kg (i.p.) did not show altered locomotor activity or changes in anxiety-like behaviour in the elevated plus maze or light-dark paradigms. Treatment with SNAP 37889 (30 mg/kg, i.p.) reduced operant responding for solutions containing ethanol, sucrose and saccharin. Collectively, results from the current study showed that SNAP 37889 (30 mg/kg, i.p.) is effective in reducing operant responding for ethanol, independent of a sedative effect. CONCLUSIONS: These findings provide evidence that GALR3 antagonism reduces alcohol consumption and further suggest that GALR3 may be implicated in the rewarding effects of natural and drug reinforcers.