The extreme toxicity of nerve agents and the broad spectrum of their physical and chemical properties, enabling the use of these agents in a variety of tactical situations, is a continuing challenge in maintaining the knowledge and capability to detect them, as well as in finding new effective methods. Despite significant advances in the instrumentation of the analysis of nerve agents, relatively simple methods based on the evaluation of colour signals (absorption and fluorescence), in particular those using the cholinesterase reaction, continue to be of importance. This review provides a brief presentation of the current status of these simple methods, with an emphasis on military applications, and illustrates the high interest of the professional community in their further development. At the same time, it also contains some peculiarities (high reliability and durability, resistance to extreme climatic conditions, work in deployed means of protection, low purchase prices, economic availability especially in a state of war, etc.) that the authors believe research and development of simple methods and means for the detection of nerve agents should respect.

• Keywords
• biosensors, chemosensors, cholinesterase reaction, colour reactions, fluorescence, nerve agents,
• MeSH
• Cholinesterases MeSH
• Nerve Agents * analysis   MeSH
• Reproducibility of Results MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Cholinesterases MeSH
• Nerve Agents * MeSH

Acetylcholinesterase (AChE) reactivators were developed for the treatment of organophosphate intoxication. Standard care involves the use of anticonvulsants (e.g., diazepam), parasympatolytics (e.g., atropine) and oximes that restore AChE activity. However, oximes also bind to the active site of AChE, simultaneously acting as reversible inhibitors. The goal of the present study is to determine how oxime structure influences the inhibition of human recombinant AChE (hrAChE). Therefore, 24 structurally different oximes were tested and the results compared to the previous eel AChE (EeAChE) experiments. Structural factors that were tested included the number of pyridinium rings, the length and structural features of the linker, and the number and position of the oxime group on the pyridinium ring.

• MeSH
• Acetylcholinesterase chemistry   MeSH
• Cholinesterase Inhibitors chemistry   MeSH
• Catalytic Domain MeSH
• Humans MeSH
• Oximes chemistry   MeSH
• Molecular Docking Simulation MeSH
• Protein Binding MeSH
• Hydrogen Bonding MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• Cholinesterase Inhibitors MeSH
• Oximes MeSH

Assay of acetylcholinesterase (AChE) activity plays an important role in diagnostic, detection of pesticides and nerve agents, in vitro characterization of toxins and drugs including potential treatments for Alzheimer's disease. These experiments were done in order to determine whether indoxylacetate could be an adequate chromogenic reactant for AChE assay evaluation. Moreover, the results were compared to the standard Ellman's method. We calculated Michaelis constant Km (2.06 × 10(-4) mol/L for acetylthiocholine and 3.21 × 10(-3) mol/L for indoxylacetate) maximum reaction velocity V(max) (4.97 × 10(-7) kat for acetylcholine and 7.71 × 10(-8) kat for indoxylacetate) for electric eel AChE. In a second part, inhibition values were plotted for paraoxon, and reactivation efficacy was measured for some standard oxime reactivators: obidoxime, pralidoxime (2-PAM) and HI-6. Though indoxylacetate is split with lower turnover rate, this compound appears as a very attractive reactant since it does not show any chemical reactivity with oxime antidots and thiol used for the Ellman's method. Thus it can be advantageously used for accurate measurement of AChE activity. Suitability of assay for butyrylcholinesterase activity assessment is also discussed.

• Keywords
• 5,5′-dithio-bis-2-nitrobenzoic acid, Alzheimer’s disease, acetylcholinesterase, enzyme activity, indoxylacetate, nerve agents, oxime reactivator,
• MeSH
• Acetylcholinesterase metabolism   MeSH
• Cholinesterase Inhibitors chemistry   metabolism   MeSH
• Enzyme Assays * MeSH
• Indoles chemistry   metabolism   MeSH
• Kinetics MeSH
• Dithionitrobenzoic Acid chemistry   metabolism   MeSH
• Obidoxime Chloride chemistry   metabolism   MeSH
• Oximes chemistry   metabolism   MeSH
• Paraoxon chemistry   metabolism   MeSH
• Pralidoxime Compounds chemistry   metabolism   MeSH
• Pyridinium Compounds chemistry   metabolism   MeSH
• Cholinesterase Reactivators chemistry   metabolism   MeSH
• Substrate Specificity MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• asoxime chloride MeSH Browser
• Cholinesterase Inhibitors MeSH
• Indoles MeSH
• indoxyl acetate MeSH Browser
• Dithionitrobenzoic Acid MeSH
• Obidoxime Chloride MeSH
• Oximes MeSH
• Paraoxon MeSH
• pralidoxime MeSH Browser
• Pralidoxime Compounds MeSH
• Pyridinium Compounds MeSH
• Cholinesterase Reactivators MeSH

The toxic effect of organophosphates is attributed to irreversible inhibition of acetylcholinesterase (AChE; EC 3.1.1.7), the enzyme that hydrolyses the neurotransmitter acetylcholine. Inhibition potency in vivo of one of the most toxic nerve agents--Russian VX (RVX;N,N-diethyl-2-[methyl-(2-methylpropoxy)phosphoryl]sulfanylethanamine) (1 x LD(50) dose administered intramuscularly, i.m.) was studied in rats. AChE in blood was inhibited by 50%, 3 min after i.m. RVX. Butylcholinesterase (BChE; EC 3.1.1.8) in plasma was inhibited less rapidly and only by 10-20%, 20 min after RVX. AChE and BChE activities in diaphragm were reduced only 35% and 15% at 30 min. While AChE and BChE activities were reduced only about 20% and 15%, respectively, the decline in activity was rapid, occurring within 3 min. These findings indicate that RVX most potently inhibits ChE outside the central nervous system.

• MeSH
• Acetylcholinesterase blood   MeSH
• Diaphragm drug effects   enzymology   MeSH
• Time Factors MeSH
• Behavior, Animal drug effects   MeSH
• Liver drug effects   enzymology   MeSH
• Rats MeSH
• Lethal Dose 50 MeSH
• Brain drug effects   enzymology   MeSH
• Organothiophosphorus Compounds toxicity   MeSH
• Rats, Wistar MeSH
• Tissue Distribution drug effects   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Acetylcholinesterase MeSH
• Organothiophosphorus Compounds MeSH
• S-(N,N-diethylaminoethyl) isobutyl methylphosphothiolate MeSH Browser

A cholinesterase based biosensor was constructed in order to assess the effects of ionizing radiation on exposed AChE. Although the primary objective of the experiment was to investigate the effect of ionizing radiation on the activity of the biosensor, no changes in cholinesterase activity were observed. Current provided by oxidation of thiocholine previously created from acetylthiocholine by enzyme catalyzed reaction was in a range 395-455 nA. No significant influence of radiation on AChE activity was found, despite the current variation. However, a surprising phenomenon was observed when a model organophosphate paraoxon was assayed. Irradiated biosensors seem to be more susceptible to the inhibitory effects of paraoxon. Control biosensors provided a 94 ± 5 nA current after exposure to 1 ppm paraoxon. The biosensors irradiated by a 5 kGy radiation dose and exposed to paraoxon provided a current of 49 ± 6 nA. Irradiation by doses ranging from 5 mGy to 100 kGy were investigated and the mentioned effect was confirmed at doses above 50 Gy. After the first promising experiments, biosensors irradiated by 5 kGy were used for calibration on paraoxon and compared with the control biosensors. Limits of detection 2.5 and 3.8 ppb were achieved for irradiated and non-irradiated biosensors respectively. The overall impact of this effect is discussed.

• Keywords
• acetylcholinesterase, biosensor, cholinesterase, nerve agents, organophosphate, paraoxon, radiation,
• Publication type
• Journal Article MeSH

Cholinesterase activity in blood of laboratory rats was monitored. Rats were intoxicated with paraoxon at dosis of 0 - 65 - 125 - 170 - 250 - 500 nmol. The 250 nmol dose was found to be the LD(50). An electrochemical sensor was found useful to provide information about cholinesterase activity. The decrease of cholinesterase activity was correlated to intoxication symptoms and mortality level. It was found that the symptoms of intoxication are not observed while at least 50% of cholinesterase activity in blood remains. The minimal cholinesterase activity essential to survival is around 10%, when compared with the initial state. No changes in levels of low moleculary weight antioxidants were observed.

• Keywords
• acetylcholinesterase, activity, blood, butyrylcholinesterase, cholinesterase, intoxication, paraoxon, pesticide,
• Publication type
• Journal Article MeSH