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International Journal of Molecular... Sep 2023Organophosphorus insecticides (OPs), acting as serine phosphorylating agents in acetylcholinesterase (AChE), are highly effective neurotoxic insecticides. In our...
Organophosphorus insecticides (OPs), acting as serine phosphorylating agents in acetylcholinesterase (AChE), are highly effective neurotoxic insecticides. In our previous research, we found that six herbivorous pests and four ladybirds howed significantly higher AChE LC50 values than seven parasitoids and a predator (), and that there was a significant correlation with the corresponding bimolecular rate constant (Ki) value. The Ki value of pests was much smaller than that of natural enemies and had a higher LC50 value.Then, we speculated that the low sensitivity of the pest AChE to OPs may be associated with its higher recovery and lower aging ability. In this work, the I50 and I90 were calculated, to determine the sensibility of AChE in ten representative species, including , , , and , to paraoxon and malaoxon. The enzyme activities were measured at various time points, and kinetic calculations were used to obtain their spontaneous reactivation (Ks) and aging (Ka) constants, which were comprehensively compared. We conclude that the Ka and Ks of the AChE inhibited by OPs showed primarily species-specific correlations, and little correlation with the sensitivity to OPs. The differences in the AChE sensitivity to paraoxon among the ten species were much greater than in the sensitivity to malaoxon. Compared to paraoxon, malaoxon was more selective for . Coleoptera insects showed a stronger dephosphorylation ability than other insect groups. The recovery ability of phospho-AChE was stronger in mammals than in insects, which could be related to the low sensitivity of the AChE site of action to OPs. The Ka of the AChE inhibited by malaoxon was larger than that inhibited by paraoxon with the corresponding biomaterials, indicating that the OP type had a substantial relationship with the Ka of the AChE. We further discovered that, when insects were inhibited by OP, the tendency of AChE to undergo aging was greater than that of dephosphorylation. Overall, the study provides valuable information on the action mechanism of various OPs on AChE in several species, which could be used to further research into AChE and the potential dangers that organophosphates pose to animals.
PubMed: 37762515
DOI: 10.3390/ijms241814213 -
The Journal of Pharmacology and... Jan 2024Synthesis of the acetylcholinesterase inhibitor paraoxon (POX) as a carbon-11 positron emission tomography tracer ([C]POX) and profiling in live rats is reported. Naïve...
Synthesis of the acetylcholinesterase inhibitor paraoxon (POX) as a carbon-11 positron emission tomography tracer ([C]POX) and profiling in live rats is reported. Naïve rats intravenously injected with [C]POX showed a rapid decrease in parent tracer to ∼1%, with an increase in radiolabeled serum proteins to 87% and red blood cells (RBCs) to 9%. Protein and RBC leveled over 60 minutes, reflecting covalent modification of proteins by [C]POX. Ex vivo biodistribution and imaging profiles in naïve rats had the highest radioactivity levels in lung followed by heart and kidney, and brain and liver the lowest. Brain radioactivity levels were low but observed immediately after injection and persisted over the 60-minute experiment. This showed for the first time that even low POX exposures (∼200 ng tracer) can rapidly enter brain. Rats given an LD dose of nonradioactive paraoxon at the LD 20 or 60 minutes prior to [C]POX tracer revealed that protein pools were blocked. Blood radioactivity at 20 minutes was markedly lower than naïve levels due to rapid protein modification by nonradioactive POX; however, by 60 minutes the blood radioactivity returned to near naïve levels. Live rat tissue imaging-derived radioactivity values were 10%-37% of naïve levels in nonradioactive POX pretreated rats at 20 minutes, but by 60 minutes the area under the curve (AUC) values had recovered to 25%-80% of naïve. The live rat imaging supported blockade by nonradioactive POX pretreatment at 20 minutes and recovery of proteins by 60 minutes. SIGNIFICANCE STATEMENT: Paraoxon (POX) is an organophosphorus (OP) compound and a powerful prototype and substitute for OP chemical warfare agents (CWAs) such as sarin, VX, etc. To study the distribution and penetration of POX into the central nervous system (CNS) and other tissues, a positron emission tomography (PET) tracer analog, carbon-11-labeled paraoxon ([C]POX), was prepared. Blood and tissue radioactivity levels in live rats demonstrated immediate penetration into the CNS and persistent radioactivity levels in tissues indicative of covalent target modification.
Topics: Rats; Animals; Paraoxon; Tissue Distribution; Acetylcholinesterase; Positron-Emission Tomography; Organophosphorus Compounds; Carbon Radioisotopes
PubMed: 37770203
DOI: 10.1124/jpet.123.001832 -
Toxics Sep 2023The contexts where there are mining and agriculture activities are potential sources of risk to human health due to contamination by chemical mixtures. These contexts...
The contexts where there are mining and agriculture activities are potential sources of risk to human health due to contamination by chemical mixtures. These contexts are frequent in several Colombian regions. This study explored the potential association between the frequency of micronuclei and pesticides and elements in regions with ferronickel (Montelibano, Córdoba) and gold (Nechí, Antioquia) mining, and a closed native mercury mine (Aranzazu, Caldas), with an emphasis in the potential effect of selenium as a potential chelator. A cross-sectional study was carried out with 247 individuals. Sociodemographic, occupational, and toxicological variables were ascertained. Blood and urine samples were taken for pesticide analysis (5 organophosphates, 4 organochlorines, and 3 carbamates), 68 elements were quantified in hair, and micronuclei were quantified in lymphocytes. The mixtures of elements were grouped through principal component analysis. Prevalence ratios were estimated with robust variance Poisson regressions to explore associations. Interactions of selenium with toxic elements were explored. The highest concentrations of elements were in the active mines. The potentially most toxic chemical mixture was observed in the ferronickel mine. Pesticides were detected in a low proportion of participants (<2.5%), except paraoxon-methyl in blood (27.55%) in Montelibano and paraoxon-ethyl in blood (18.81%) in Aranzazu. The frequency of micronuclei was similar in the three mining contexts, with means between 4 to 7 ( = 0.1298). There was great heterogeneity in the exposure to pesticides and elements. The "hormetic effect" of selenium was described, in which, at low doses, it acts as a chelator in Montelibano and Aranzazu, and at high doses, it can enhance the toxic effects of other elements, maybe as in Nechí. Selenium can serve as a protective agent, but it requires adaptation to the available concentrations in each region to avoid its toxic effects.
PubMed: 37888671
DOI: 10.3390/toxics11100821 -
Toxics Aug 2023Organophosphate pesticides (OPs) are toxic substances that contaminate aquatic environments, interfere with the development of the nervous system, and induce...
Organophosphate pesticides (OPs) are toxic substances that contaminate aquatic environments, interfere with the development of the nervous system, and induce Neurodevelopmental Toxicity (NDT) in animals and humans. The canonical mechanism of OP neurotoxicity involves the inhibition of acetylcholinesterase (AChE), but other mechanisms non-AChE are also involved and not fully understood. We used network toxicology and molecular docking to identify molecular targets and toxicity mechanisms common to OPs. Targets related to diazinon-oxon, chlorpyrifos oxon, and paraoxon OPs were predicted using the Swiss Target Prediction and PharmMapper databases. Targets related to NDT were compiled from GeneCards and OMIM databases. In order to construct the protein-protein interaction (PPI) network, the common targets between OPs and NDT were imported into the STRING. Network topological analyses identified EGFR, MET, HSP90AA1, and SRC as hub nodes common to the three OPs. Using the Reactome pathway and gene ontology, we found that signal transduction, axon guidance, cellular responses to stress, and glutamatergic signaling activation play key roles in OP-induced NDT.
PubMed: 37624215
DOI: 10.3390/toxics11080710 -
Tuning the Envelope Structure of Enzyme Nanoreactors for In Vivo Detoxification of Organophosphates.International Journal of Molecular... Oct 2023Encapsulated phosphotriesterase nanoreactors show their efficacy in the prophylaxis and post-exposure treatment of poisoning by paraoxon. A new enzyme nanoreactor...
Encapsulated phosphotriesterase nanoreactors show their efficacy in the prophylaxis and post-exposure treatment of poisoning by paraoxon. A new enzyme nanoreactor (E-nRs) containing an evolved multiple mutant (L72C/Y97F/Y99F/W263V/I280T) of phosphotriesterase (PTE) for in vivo detoxification of organophosphorous compounds (OP) was made. A comparison of nanoreactors made of three- and di-block copolymers was carried out. Two types of morphology nanoreactors made of di-block copolymers were prepared and characterized as spherical micelles and polymersomes with sizes of 40 nm and 100 nm, respectively. The polymer concentrations were varied from 0.1 to 0.5% (/) and enzyme concentrations were varied from 2.5 to 12.5 μM. In vivo experiments using E-nRs of diameter 106 nm, polydispersity 0.17, zeta-potential -8.3 mV, and loading capacity 15% showed that the detoxification efficacy against paraoxon was improved: the LD shift was 23.7xLD for prophylaxis and 8xLD for post-exposure treatment without behavioral alteration or functional physiological changes up to one month after injection. The pharmacokinetic profiles of i.v.-injected E-nRs made of three- and di-block copolymers were similar to the profiles of the injected free enzyme, suggesting partial enzyme encapsulation. Indeed, ELISA and Western blot analyses showed that animals developed an immune response against the enzyme. However, animals that received several injections did not develop iatrogenic symptoms.
Topics: Animals; Organophosphates; Paraoxon; Phosphoric Triester Hydrolases; Nanotechnology
PubMed: 37958742
DOI: 10.3390/ijms242115756 -
Scientific Reports Nov 2023Organophosphorus poisoning kills individuals by causing central apnea; however, the underlying cause of death remains unclear. Following findings that the pre-Bötzinger...
Organophosphorus poisoning kills individuals by causing central apnea; however, the underlying cause of death remains unclear. Following findings that the pre-Bötzinger complex impairment alone does not account for central apnea, we analyzed the effect of paraoxon on the brainstem-spinal cord preparation, spanning the lower medulla oblongata to phrenic nucleus. Respiratory bursts were recorded by connecting electrodes to the ventral 4th cervical nerve root of excised brainstem-spinal cord preparations obtained from 6-day-old Sprague-Dawley rats. We observed changes in respiratory bursts when paraoxon, neostigmine, atropine, and 2-pyridine aldoxime methiodide were administered via bath application. The percentage of burst extinction in the paraoxon-poisoning group was 50% compared with 0% and 18.2% in the atropine and 2-pyridine aldoxime methiodide treatment groups, respectively. Both treatments notably mitigated the paraoxon-induced reduction in respiratory bursts. In the neostigmine group, similar to paraoxon, bursts stopped in 66.7% of cases but were fully reversed by atropine. This indicates that the primary cause of central apnea is muscarinic receptor-mediated in response to acetylcholine excess. Paraoxon-induced central apnea is hypothesized to result from neural abnormalities within the inferior medulla oblongata to the phrenic nucleus, excluding pre-Bötzinger complex. These antidotes antagonize central apnea, suggesting that they may be beneficial therapeutic agents.
Topics: Rats; Animals; Antidotes; Paraoxon; Rats, Sprague-Dawley; Neostigmine; Sleep Apnea, Central; Atropine; Pralidoxime Compounds; Pyridines
PubMed: 37990100
DOI: 10.1038/s41598-023-47745-x -
The Journal of Rheumatology Jul 2023This posthoc analysis investigated the relationship between paraoxonase-1 (PON1) genotype and activity, and risk of major adverse cardiovascular events (MACE) and...
Relationship Between Paraoxonase-1 Genotype and Activity, and Major Adverse Cardiovascular Events and Malignancies in Patients With Rheumatoid Arthritis Receiving Tofacitinib.
OBJECTIVE
This posthoc analysis investigated the relationship between paraoxonase-1 (PON1) genotype and activity, and risk of major adverse cardiovascular events (MACE) and malignancies in clinical studies of tofacitinib in patients with rheumatoid arthritis (RA).
METHODS
Data were pooled from 9 phase II/III studies and the associated long-term extension studies (all completed by October 2017). PON1 activities in plasma were measured using paraoxon (paraoxonase activity), dihydrocoumarin (lactonase activity), and phenylacetate (arylesterase activity) as substrates. PON1 Q192R genotype effect on baseline PON1 activity was assessed using linear regression for each study, with fixed-effects metaanalysis across studies. MACE and malignancy risk by time-varying enzyme activity was determined using Cox proportional hazards regression.
RESULTS
The analysis included 1969 patients with RA. Compared with the QQ genotype, the RR genotype had a significant positive association with baseline paraoxonase activity and a significant negative association with baseline lactonase and arylesterase activity (all < 0.001). Time-varying models demonstrated a significant association of increased paraoxonase activity over time with lower risk of MACE ( < 0.001) and malignancies (excluding nonmelanoma skin cancer [NMSC]; ≤ 0.05), even after controlling for risk factors identified in univariate analysis and RA disease activity. A similar trend was observed for lactonase and arylesterase for MACE.
CONCLUSION
Higher paraoxonase activity over time was associated with significantly reduced risk of future MACE and malignancies (excluding NMSC), but not NMSC, in patients with RA receiving tofacitinib. Further investigation of PON1 as a novel functional lipid biomarker of MACE/malignancy risk in patients with RA is warranted. (ClinicalTrials.gov: NCT01059864, NCT00550446, NCT00687193, NCT00960440, NCT00814307, NCT00856544, NCT00853385, NCT00847613, NCT01039688, NCT00413699, NCT00661661).
PubMed: 37453736
DOI: 10.3899/jrheum.2023-0112 -
ACS Applied Materials & Interfaces Jul 2023The development of bio-MOFs or MOF biocomposites through the combination of MOFs with biopolymers offers the possibility of expanding the potential applications of MOFs,...
The development of bio-MOFs or MOF biocomposites through the combination of MOFs with biopolymers offers the possibility of expanding the potential applications of MOFs, making use of more environmentally benign processes and reagents and giving rise to a new generation of greener and more bio-oriented composite materials. Now, with the increasing use of MOFs for biotechnological applications, the development of new protocols and materials to obtain novel bio-MOFs compatible with biomedical or biotechnological uses is needed. Herein, and as a proof of concept, we have explored the possibility of using short-peptide supramolecular hydrogels as media to promote the growth of MOF particles, giving rise to a new family of bio-MOFs. Short-peptide supramolecular hydrogels are very versatile materials that have shown excellent in vitro and in vivo biomedical applications such as tissue engineering and drug delivery vehicles, among others. These peptides self-assemble by noncovalent interactions, and, as such, these hydrogels are easily reversible, being more biocompatible and biodegradable. These peptides can self-assemble by a multitude of stimuli, such as changes in pH, temperature, solvent, adding salts, enzymatic activity, and so forth. In this work, we have taken advantage of this ability to promote peptide self-assembly with some of the components required to form MOF particles, giving rise to more homogeneous and well-integrated composite materials. Hydrogel formation has been triggered using Zn salts, required to form ZIF-8, and formic acid, required to form MOF-808. Two different protocols for the in situ MOF growth have been developed. Finally, the MOF-808 composite hydrogel has been tested for the decontamination of water polluted with phosphate ions as well as for the catalytic degradation of toxic organophosphate methyl paraoxon in an unbuffered solution.
Topics: Metal-Organic Frameworks; Hydrogels; Salts; Peptides; Drug Delivery Systems
PubMed: 37390355
DOI: 10.1021/acsami.3c06943 -
Frontiers in Pharmacology 2023Organophosphate-based chemical agents (OP), including nerve agents and certain pesticides such as paraoxon, are potent acetylcholinesterase inhibitors that cause severe...
Organophosphate-based chemical agents (OP), including nerve agents and certain pesticides such as paraoxon, are potent acetylcholinesterase inhibitors that cause severe convulsions and seizures, leading to permanent central nervous system (CNS) damage if not treated promptly. The current treatment regimen for OP poisoning is intramuscular injection of atropine sulfate with an oxime such as pralidoxime (2-PAM) to mitigate cholinergic over-activation of the somatic musculature and autonomic nervous system. This treatment does not provide protection against CNS cholinergic overactivation and therefore convulsions require additional medication. Benzodiazepines are the currently accepted treatment for OP-induced convulsions, but the convulsions become refractory to these GABA agonists and repeated dosing has diminishing effectiveness. As such, adjunct anticonvulsant treatments are needed to provide improved protection against recurrent and prolonged convulsions and the associated excitotoxic CNS damage that results from them. Previously we have shown that brief, 4-min administration of 3%-5% isoflurane in 100% oxygen has profound anticonvulsant and CNS protective effects when administered 30 min after a lethal dose of paraoxon. In this report we provide an extended time course of the effectiveness of 5% isoflurane delivered for 5 min, ranging from 60 to 180 min after a lethal dose of paraoxon in rats. We observed substantial effectiveness in preventing neuronal loss as shown by Fluoro-Jade B staining when isoflurane was administered 1 h after paraoxon, with diminishing effectiveness at 90, 120 and 180 min. magnetic resonance imaging (MRI) derived T2 and mean diffusivity (MD) values showed that 5-min isoflurane administration at a concentration of 5% prevents brain edema and tissue damage when administered 1 h after a lethal dose of paraoxon. We also observed reduced astrogliosis as shown by GFAP immunohistochemistry. Studies with continuous EEG monitoring are ongoing to demonstrate effectiveness in animal models of soman poisoning.
PubMed: 38230376
DOI: 10.3389/fphar.2023.1293280 -
RSC Advances Oct 2023The use of organophosphate (OPs) pesticides is widespread in agriculture and horticulture, but these chemicals can be lethal to humans, causing fatalities and deaths...
The use of organophosphate (OPs) pesticides is widespread in agriculture and horticulture, but these chemicals can be lethal to humans, causing fatalities and deaths each year. The inhibition of acetylcholinesterase (AChE) by OPs leads to the overstimulation of cholinergic receptors, ultimately resulting in respiratory arrest, seizures, and death. Although 2-pralidoxime (2-PAM) is the FDA-approved drug for treating OP poisoning, there is difficulty in blood-brain barrier permeation. To address this issue, we designed and evaluated a series of 2-PAM analogs by substituting electron-donating groups on the and/or positions of the pyridinium core using techniques. Our PCM-ONIOM2 (MP2/6-31G*:PM7//B3LYP/6-31G*:UFF) binding energy results demonstrated that 13 compounds exhibited higher binding energy than 2-PAM. The analog with phenyl and methyl groups substituted on the and positions, respectively, showed the most favorable binding characteristics, with aromatic residues in the active site (Y124, W286, F297, W338, and Y341) and the catalytic residue S203 covalently bonding with paraoxon. The results of DS-MD simulation revealed a highly favorable apical conformation of the potent analog, which has the potential to enhance reactivation of AChE. Importantly, newly designed compound demonstrated appropriate drug-likeness properties and blood-brain barrier penetration. These results provide a rational guide for developing new antidotes to treat organophosphate insecticide toxicity.
PubMed: 37928857
DOI: 10.1039/d3ra03087c