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Pharmacology Research & Perspectives Feb 2015One of the major signs of severe organophosphate poisoning is seizures. Previous studies have shown that both muscarinic agonist- and organophosphate-induced seizures...
One of the major signs of severe organophosphate poisoning is seizures. Previous studies have shown that both muscarinic agonist- and organophosphate-induced seizures require activation of muscarinic acetylcholine receptors in the central nervous system. Seizures induced by the muscarinic agonist pilocarpine require the M1 receptor and are modulated by cannabinoid CB1 receptors. In this study, we determined whether M1 and CB1 receptors also regulated seizures induced by the organophosphate paraoxon. We found no differences in seizures induced by paraoxon in wild-type (WT) and M1 knockout (KO) mice, indicating that in contrast to pilocarpine seizures, M1 receptors are not required for paraoxon seizures. Furthermore, we found that pilocarpine administration resulted in seizure-independent activation of ERK in the hippocampus in a M1 receptor-dependent manner, while paraoxon did not induce seizure-independent activation of ERK in the mouse hippocampus. This shows that pilocarpine and paraoxon activated M1 receptors in the hippocampus to different extents. There were no differences in seizures induced by paraoxon in WT and CB1 KO mice, and neither CB1 agonist nor antagonist administration had significant effects on paraoxon seizures, indicating that, in contrast to pilocarpine seizures, paraoxon seizures are not modulated by CB1 receptors. These results demonstrate that there are fundamental molecular differences in the regulation of seizures induced by pilocarpine and paraoxon.
PubMed: 25692018
DOI: 10.1002/prp2.100 -
RSC Medicinal Chemistry Apr 2024Previously we reported two salicylaldoxime conjugates (L7R3 and L7R5) showing equal or even higher reactivating efficiency for both organophosphorus nerve agent and...
Previously we reported two salicylaldoxime conjugates (L7R3 and L7R5) showing equal or even higher reactivating efficiency for both organophosphorus nerve agent and pesticide inhibited acetylcholinesterase in comparison to obidoxime and HI-6. In this study, L7R3 and L7R5 were selected as lead compounds and refined by employing a fragment-based drug design strategy, and a total of 32 novel salicylaldoxime conjugates were constructed and screened for DFP and paraoxon inhibited acetylcholinesterase. The findings demonstrate that the conjugate L73R3, which contains a 4-nitrophenyl group, exhibited a higher reactivation efficacy against paraoxon-inhibited acetylcholinesterase compared to obidoxime and HI-6. It was confirmed that the combination of a 4-pyridinyl or 4-nitrophenyl peripheral site ligand, a piperazine linker and a methyl or chloro-substituted salicylaldoxime could construct efficient nonquaternary oxime reactivators. The results hold promise for developing a new generation of highly effective antidotes for organophosphate poisoning.
PubMed: 38665821
DOI: 10.1039/d3md00628j -
Toxicology Dec 2018Some effects of organophosphorus compounds (OPs) esters cannot be explained by action on currently recognized targets acetylcholinesterase or neuropathy target esterase...
Some effects of organophosphorus compounds (OPs) esters cannot be explained by action on currently recognized targets acetylcholinesterase or neuropathy target esterase (NTE). In previous studies, in membrane chicken brain fractions, four components (EPα, EPβ, EPγ and EPδ) of phenyl valerate esterase activity (PVase) had been kinetically discriminated combining data of several inhibitors (paraoxon, mipafox, PMSF). EPγ is belonging to NTE. The relationship of PVase components and acetylcholine-hydrolyzing activity (cholinesterase activity) is studied herein. Only EPα PVase activity showed inhibition in the presence of acetylthiocholine, similarly to a non-competitive model. EPα is highly sensitive to mipafox and paraoxon, but is resistant to PMSF, and is spontaneously reactivated when inhibited with paraoxon. In this papers we shows that cholinesterase activities showed inhibition kinetic by PV, which does not fit with a competitive inhibition model when tested for the same experimental conditions used to discriminate the PVase components. Four enzymatic components (CP1, CP2, CP3 and CP4) were discriminated in cholinesterase activity in the membrane fraction according to their sensitivity to irreversible inhibitors mipafox, paraoxon, PMSF and iso-OMPA. Components CP1 and CP2 could be related to EPα as they showed interactions between substrates and similar inhibitory kinetic properties to the tested inhibitors.
Topics: Animals; Binding, Competitive; Brain; Carboxylic Ester Hydrolases; Chickens; Cholinesterase Inhibitors; Cholinesterases; Kinetics; Membranes; Organophosphorus Compounds
PubMed: 30176330
DOI: 10.1016/j.tox.2018.08.018 -
Annals of the New York Academy of... Jun 2016In addition to the global use of organophosphate (OP) pesticides for agriculture, OP nerve agents and pesticides have been employed on battlefields and by terrorists... (Review)
Review
In addition to the global use of organophosphate (OP) pesticides for agriculture, OP nerve agents and pesticides have been employed on battlefields and by terrorists (e.g., a recent sarin attack in Syria). These occurrences highlight the need for an effective countermeasure against OP exposure. Human butyrylcholinesterase (HuBChE) is a leading candidate, but injection of the high doses required for protection present pharmacokinetic challenges. An aerosolized recombinant form (aer-rHuBChE) that can neutralize inhaled OPs at the portal of entry has been assessed for its efficacy in protecting macaques against respiratory toxicity following inhalation exposure to the pesticide paraoxon (aer-Px). While protection in macaques has been demonstrated using the MicroSprayer® delivery device, administration to humans will likely employ a vibrating mesh nebulizer (VMN). Compared to the 50-70% lung deposition achieved in adult humans with a VMN, deposition in macaques is <5%, an initial major obstacle to demonstrating protection. Such problems have been partly overcome by using a more efficient modified VMN and proportionally higher doses, which together generate an effective rHuBChE pulmonary bioshield and protect against high levels of inhaled Px.
Topics: Aerosols; Animals; Drug Delivery Systems; Humans; Inhalation Exposure; Lung; Organophosphorus Compounds; Protective Agents
PubMed: 27371808
DOI: 10.1111/nyas.13106 -
Analytical Chemistry Nov 2022Mn(II)-based electron spin resonance (ESR) spectroscopy was used for detecting butyrylcholinesterase (BChE) and organophosphorus pesticides (OPs). MnO nanosheets were...
Label-Free and Ultrasensitive Detection of Butyrylcholinesterase and Organophosphorus Pesticides by Mn(II)-Based Electron Spin Resonance Spectroscopy with a Zero Background Signal.
Mn(II)-based electron spin resonance (ESR) spectroscopy was used for detecting butyrylcholinesterase (BChE) and organophosphorus pesticides (OPs). MnO nanosheets were synthesized with manganese chloride and hydrogen peroxide. With the catalysis of BChE, S-butyrylthiocholine iodide (BTCh) was hydrolyzed into thiocholine which has a reducing -SH group. In the presence of thiocholine, MnO nanosheets were broken down and Mn(IV) in MnO nanosheets was reduced into Mn(II). Mn is a paramagnetic ion and gives a good ESR signal. In contrast, MnO nanosheets have no ESR signal and need not be separated from Mn. Mn can be determined directly by ESR spectroscopy, and no further sensing probe is needed. ESR spectroscopy based on directly detecting Mn is much simpler than those using other probes besides MnO. The ESR signal of Mn is proportional to the catalytic activity of BChE. OPs which inhibit the activity of BChE can also be detected by probing the ESR signal of Mn. Since there is no ESR signal of MnO nanosheets, the background signal in the absence of BChE was close to zero. The limit of detection (LOD) of BChE was as low as 0.042 U L. The standard curve for determining the OP paraoxon was established by measuring the inhibition of BChE by paraoxon, and the LOD of paraoxon was found to be 0.076 ng mL. The spiked Chinese cabbage extract samples were analyzed, and the experimental results indicated that the recoveries were from 96.5 to 102.8%. The planted Chinese cabbage was sprayed with the paraoxon solution, and the residue amount of paraoxon in the extract was estimated by the method. The result obtained by the present method was consistent with that obtained by HPLC, which proved the practicability of this new method.
Topics: Butyrylcholinesterase; Manganese Compounds; Pesticides; Paraoxon; Organophosphorus Compounds; Electron Spin Resonance Spectroscopy; Oxides; Thiocholine
PubMed: 36332200
DOI: 10.1021/acs.analchem.2c03708 -
Environmental Science. Processes &... Dec 2022Parathion, a once commonly used pesticide known for its potential toxicity, can follow several degradation mechanisms in the environment. Given the species stability and...
Parathion, a once commonly used pesticide known for its potential toxicity, can follow several degradation mechanisms in the environment. Given the species stability and persistence, parathion can be washed into waterways from rain, and therefore an atomistic perspective of the hydrolysis of parathion, and its byproduct paraoxon, is required in order to understand its fate in the environment. Experimental studies have determined that pH plays an important role in the calculated hydrolysis rate constants of parathion degradation. In this work, the degradation of parathion into either paraoxon or 4-nitrophenol, and the degradation of paraoxon to 4-nitrophenol are explored through density functional theory using the M06-2X functional. How the level of basicity affects the reaction mechanism is explored through two different hydroxide/water environments. Our calculations support the anticipated mechanisms determined by previous experimental work that the formation of 4-nitrophenol is the predominant pathway in hydrolysis of parathion.
Topics: Parathion; Paraoxon; Hydrolysis; Density Functional Theory
PubMed: 36129094
DOI: 10.1039/d2em00296e -
ACS Applied Materials & Interfaces Dec 2019Inspired by blood coagulation and mussel adhesion, we report novel adhesive fibrin-bone@polydopamine (PDA)-shell composite matrix as highly efficient immobilization...
Inspired by blood coagulation and mussel adhesion, we report novel adhesive fibrin-bone@polydopamine (PDA)-shell composite matrix as highly efficient immobilization platform for biomacromolecules and nanomaterials. Fibrin, as a bioglue, and PDA, as a chemical adhesive, are integrated in a one-pot simultaneous polymerization consisting of biopolymerization of fibrinogen and chemical polymerization of dopamine. Fibrin fibers act as adhesive bones to construct scaffold, while PDA coat on the scaffold to form adhesive shell, generating 3D porous composite matrix with unique bone@shell structure. Two types of enzymes (glucose oxidase and acetylcholinesterase) and Au nanoparticles were adopted as respective model biomolecules and nanomaterials to investigate the immobilization capability of the matrix. The bionanocomposites showed high efficiency in capturing nanoparticles and enzymes, as well as significant mass-transfer and biocatalysis efficiencies. Therefore, the bionanocomposites exhibited significant potential in biosensing of glucose and paraoxon with limits of detection down to 5.2 μM and 4 ppt, respectively. The biological-chemical-combined polymerization strategy and composite platform with high immobilization capacity and mass-transfer efficiency open up a novel way for the preparation of high-performance bionanocomposites for various applications, in particular, biosensing.
Topics: Adhesives; Biocatalysis; Biosensing Techniques; Dopamine; Enzymes, Immobilized; Fibrin; Fibrinogen; Glucose; Glucose Oxidase; Gold; Humans; Indoles; Limit of Detection; Metal Nanoparticles; Paraoxon; Polymerization; Polymers
PubMed: 31742992
DOI: 10.1021/acsami.9b15376 -
International Journal of Analytical... 2022Biosensors containing cholinesterase are analytical devices suitable for the assay of neurotoxic compounds. In the research on biosensors, a new platform has appeared...
Biosensors containing cholinesterase are analytical devices suitable for the assay of neurotoxic compounds. In the research on biosensors, a new platform has appeared some years ago. It is the digital photography and scoring of coloration (photogrammetry). In this paper, a colorimetric biosensor is constructed using 3D-printed multiwell pads treated with indoxylacetate as a chromogenic substrate and gold nanoparticles with the immobilized enzyme butyrylcholinesterase. A smartphone camera served for photogrammetry. The biosensor was tested for the assay of carbofuran and paraoxon ethyl as two types of covalently binding inhibitors: irreversible and pseudoirreversible. The biosensor exerted good sensitivity to the inhibitors and was able to detect carbofuran with a limit of detection for carbofuran 7.7 nmol/l and 17.6 nmol/l for paraoxon ethyl. A sample sized 25 l was suitable for the assay lasting approximately 70 minutes. Up to 121 samples can be measured contemporary using one multiwell pad. The received data fully correlated with the standard spectrophotometry. The colorimetric biosensor exerts promising specifications and appears to be competitive to the other analytical procedures working on the principle of cholinesterase inhibition. Low-cost, simple, and portable design represent an advantage of the assay of the biosensor. Despite the overall simplicity, the biosensor can fully replace the standard spectroscopic methods.
PubMed: 35432544
DOI: 10.1155/2022/2623155 -
ACS Applied Materials & Interfaces May 2022A nanoreactor containing an evolved mutant of phosphotriesterase (L72C/Y97F/Y99F/W263V/I280T) as a catalytic bioscavenger was made for detoxification of...
A nanoreactor containing an evolved mutant of phosphotriesterase (L72C/Y97F/Y99F/W263V/I280T) as a catalytic bioscavenger was made for detoxification of organophosphates. This nanoreactor intended for treatment of organophosphate poisoning was studied against paraoxon (POX). Nanoreactors were low polydispersity polymersomes containing a high concentration of enzyme (20 μM). The polyethylene glycol-polypropylene sulfide membrane allowed for penetration of POX and exit of hydrolysis products. simulations under second order conditions showed that 1 μM enzyme inactivates 5 μM POX in less than 10 s. LD-shift experiments of POX-challenged mice through intraperitoneal () and subcutaneous () injections showed that intravenous administration of nanoreactors (1.6 nmol enzyme) protected against 7 × LD . in prophylaxis and 3.3 × LD in post-exposure treatment. For mice -challenged, LD shifts were more pronounced: 16.6 × LD in prophylaxis and 9.8 × LD in post-exposure treatment. Rotarod tests showed that transitory impaired neuromuscular functions of challenged mice were restored the day of experiments. No deterioration was observed in the following days and weeks. The high therapeutic index provided by prophylactic administration of enzyme nanoreactors suggests that no other drugs are needed for protection against acute POX toxicity. For post-exposure treatment, co-administration of classical drugs would certainly have beneficial effects against transient incapacitation.
Topics: Animals; Mice; Nanotechnology; Organophosphate Poisoning; Organophosphates; Paraoxon; Phosphoric Triester Hydrolases
PubMed: 35440137
DOI: 10.1021/acsami.2c03210 -
International Journal of Molecular... Dec 2021The delayed effects of acute intoxication by organophosphates (OPs) are poorly understood, and the various experimental animal models often do not take into account...
The delayed effects of acute intoxication by organophosphates (OPs) are poorly understood, and the various experimental animal models often do not take into account species characteristics. The principal biochemical feature of rodents is the presence of carboxylesterase in blood plasma, which is a target for OPs and can greatly distort their specific effects. The present study was designed to investigate the nephrotoxic effects of paraoxon (O,O-diethyl O-(4-nitrophenyl) phosphate, POX) using three models of acute poisoning in outbred Wistar rats. In the first model (, POX2x group), POX was administered twice at doses 110 µg/kg and 130 µg/kg subcutaneously, with an interval of 1 h. In the second model (, CBPOX group), 1 h prior to POX poisoning at a dose of 130 µg/kg subcutaneously, carboxylesterase activity was pre-inhibited by administration of specific inhibitor cresylbenzodioxaphosphorin oxide (CBDP, 3.3 mg/kg intraperitoneally). In the third model (), POX was administered subcutaneously just once at doses of LD16 (241 µg/kg), LD50 (250 µg/kg), and LD84 (259 µg/kg). Animal observation and sampling were performed 1, 3, and 7 days after the exposure. Endogenous creatinine clearance (ECC) decreased in 24 h in the POX2x group ( = 0.011). Glucosuria was observed in rats 24 h after exposure to POX in both M1 and M2 models. After 3 days, an increase in urinary excretion of chondroitin sulfate (CS, = 0.024) and calbindin ( = 0.006) was observed in rats of the CBPOX group. Morphometric analysis revealed a number of differences most significant for rats in the CBPOX group. Furthermore, there was an increase in the area of the renal corpuscles ( = 0.0006), an increase in the diameter of the lumen of the proximal convoluted tubules (PCT, = 0.0006), and narrowing of the diameter of the distal tubules ( = 0.001). After 7 days, the diameter of the PCT lumen was still increased in the nephrons of the CBPOX group ( = 0.0009). In the model, histopathological and ultrastructural changes in the kidneys were revealed after the exposure to POX at doses of LD50 and LD84. Over a period from 24 h to 3 days, a significant ( = 0.018) expansion of Bowman's capsule was observed in the kidneys of rats of both the LD50 and LD84 groups. In the epithelium of the proximal tubules, stretching of the basal labyrinth, pycnotic nuclei, and desquamation of microvilli on the apical surface were revealed. In the epithelium of the distal tubules, partial swelling and destruction of mitochondria and pycnotic nuclei was observed, and nuclei were displaced towards the apical surface of cells. After 7 days of the exposure to POX, an increase in the thickness of the glomerular basement membrane (GBM) was observed in the LD50 and LD84 groups ( = 0.019 and 0.026, respectively). Moreover, signs of damage to tubular epithelial cells persisted with blockage of the tubule lumen by cellular detritus and local destruction of the surface of apical cells. Comparison of results from the three models demonstrates that the nephrotoxic effects of POX, evaluated at 1 and 3 days, appear regardless of prior inhibition of carboxylesterase activity.
Topics: Animals; Biomarkers; Bowman Capsule; Creatinine; Kidney; Kidney Tubules, Proximal; Male; Nephrons; Paraoxon; Rats; Rats, Wistar
PubMed: 34948422
DOI: 10.3390/ijms222413625