-
Toxicology Mechanisms and Methods May 2024Organophosphate (OP) poisoning, both accidental and with suicidal intent, is a global medical challenge. While the primary toxicity of these pesticides is based on the...
Organophosphate (OP) poisoning, both accidental and with suicidal intent, is a global medical challenge. While the primary toxicity of these pesticides is based on the inhibition of acetylcholinesterase (AChE), case reports describe patients developing OP-mediated renal insufficiency. We set out to investigate possible pathomechanisms utilizing rat precision-cut kidney slices (PCKS). Depending on the method of investigation, PCKS were observed for a maximum of 10 days. PCKS exposed to OP compounds (malaoxon, malathion, paraoxon, parathion) showed a dose-dependent loss of viability and a reduction of total protein content over the course of 10 days. A concentration of 500 µM OP showed the most differences between OP compounds. After two days of incubation parathion showed a significantly lower level of viability than malathion. The respective effects of paraoxon and malaoxon were not significantly different from the control. However, effects of OP were only observed in concentrations exceeding those that were needed to achieve significant AChE inhibition in rat kidney tissue. In addition, we observed histological changes, without inducing LDH leakage. Overall, results suggest that OP exert effects in kidney tissue, that exceed those expected from the sole inhibition of AChE and vary between compounds. Without signs of necrosis, findings call for studies that address other possible pathomechanisms, including inflammatory response, oxidative stress or activation of apoptosis to further understand the nephrotoxicity of OP compounds. Monitoring oxon concentration over time, we demonstrated reduced enzyme-inhibiting properties in the presence of PCKS, suggesting interactions between OP compound and kidney tissue.
PubMed: 38745427
DOI: 10.1080/15376516.2024.2356184 -
Clinical Toxicology (Philadelphia, Pa.) May 2024Intentional and unintentional organophosphorus pesticide exposure is a public health concern. Organothiophosphate compounds require metabolic bioactivation by the...
INTRODUCTION
Intentional and unintentional organophosphorus pesticide exposure is a public health concern. Organothiophosphate compounds require metabolic bioactivation by the cytochrome P450 system to their corresponding oxon analogues to act as potent inhibitors of acetylcholinesterase. It is known that interactions between cytochrome P450 and pesticides include the inhibition of major xenobiotic metabolizing cytochrome P450 enzymes and changes on the genetic level.
METHODS
In this study, the influence of the pesticides parathion and paraoxon on human cytochrome P450 and associated oxygenases was investigated with a metabolically competent cell line (HepaRG cells). First, the viability of the cells after exposure to parathion and paraoxon was evaluated. The inhibitory effect of both pesticides on cytochrome P450 3A4, which is a pivotal enzyme in the metabolism of xenobiotics, was examined by determining the dose-response curve. Changes on the transcription level of 92 oxygenase associated genes, including those for important cytochrome P450 enzymes, were evaluated.
RESULTS
The exposure of HepaRG cells to parathion and paraoxon at concentrations up to 100 µM resulted in a viability of 100 per cent. After exposure for 24 hours, pronounced inhibition of cytochrome P450 3A4 enzyme activity was shown, indicating 50 per cent effective concentrations of 1.2 µM (parathion) and 2.1 µM (paraoxon). The results revealed that cytochrome P450 involved in parathion metabolism were significantly upregulated.
DISCUSSION
Relevant changes of the cytochrome P450 3A4 enzyme activity and significant alteration of genes associated with cytochrome P450 suggest an interference of pesticide exposure with numerous metabolic processes. The major limitations of the work involve the use of a single pesticide and the model as surrogate to human hepatocytes.
CONCLUSION
The data of this study might be of relevance after survival of acute, life-threatening intoxications with organophosphorus compounds, particularly for the co-administration of drugs, which are metabolized by the affected cytochrome P450.
Topics: Humans; Paraoxon; Parathion; Cell Survival; Pesticides; Dose-Response Relationship, Drug; Cytochrome P-450 Enzyme System; Cytochrome P-450 CYP3A; Insecticides; Cell Line; Cholinesterase Inhibitors
PubMed: 38874383
DOI: 10.1080/15563650.2024.2361879 -
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 -
Sustainable ionic liquids-based molecular platforms for designing acetylcholinesterase reactivators.Chemico-biological Interactions Nov 2023We report a green chemistry approach for preparation of oxime-functionalized ILs as AChE reactivators: amide/ester linked IL, l-alanine, and l-phenylalanine derived...
We report a green chemistry approach for preparation of oxime-functionalized ILs as AChE reactivators: amide/ester linked IL, l-alanine, and l-phenylalanine derived salts bearing pyridinium aldoxime moiety. The reactivation capacities of the novel oximes were evaluated towards AChE inhibited by typical toxic organophosphates, sarin (GB), VX, and paraoxon (PON). The studied compounds are mostly non-toxic up to the highest concentrations screened (2 mM) towards Gram-negative and Gram-positive bacteria cell lines and both filamentous fungi and yeasts in the in vitro screening experiments as well as towards the eukaryotic cell (CHO-K1 cell line). Introduction of the oxime moiety in initially biodegradable structure decreases its ability to biodegradation. The compound 3d was shown to reveal remarkable activity against the AChE inhibited by VX, exceeding conventional reactivators 2-PAM and obidoxime. The regularities on antidotal activity, cell viability, plasma stability, biodegradability as well as molecular docking study of the newly synthesized oximes will be used for further improvement of their structures.
Topics: Acetylcholinesterase; Ionic Liquids; Molecular Docking Simulation; Oximes; Antidotes; Cholinesterase Reactivators; Cholinesterase Inhibitors; Pyridinium Compounds
PubMed: 37802409
DOI: 10.1016/j.cbi.2023.110735 -
Talanta Jun 2024Methyl paraoxon (MP) is a highly toxic, efficient and broad-spectrum organophosphorus pesticide, which poses significant risks to ecological environment and human...
Methyl paraoxon (MP) is a highly toxic, efficient and broad-spectrum organophosphorus pesticide, which poses significant risks to ecological environment and human health. Many detection methods for MP are based on the enzyme catalytic or inhibition effect. But natural biological enzymes are relatively expensive and easy to be inactivated with a short service life. As a unique tool of nanotechnology with enzyme-like characteristics, nanozyme has attracted increasing concern. However, a large proportion of nanozymes lack the intrinsic specificity, becoming a main barrier of constraining their use in biochemical analysis. Here, we use a one-pot reverse microemulsion polymerization combine the gold nanoclusters (AuNCs) with molecularly imprinted polymers (MIPs), polydopamine (PDA) and hollow CeO nanospheres to synthesize the bright red-orange fluorescence probe (CeO@PDA@AuNCs-MIPs) with high phosphatase-like activity for selective detection of MP. The hollow structure possesses a specific surface area and porous matrix, which not only increases the exposure of active sites but also enhances the efficiency of mass and electron transport. Consequently, this structure significantly enhances the catalytic activity by reducing transport distances. The introduced MIPs provide the specific recognition sites for MP. And Ce (III) can excite aggregation induced emission of AuNCs and enhance the fluorescent signal. The absolute fluorescence quantum yield (FLQY) of CeO@PDA@AuNCs-MIPs (1.41 %) was 12.8-fold higher than that of the GSH-AuNCs (0.11 %). With the presence of MP, Ce (IV)/Ce (III) species serve as the active sites to polarize and hydrolyze phosphate bonds to generate p-nitrophenol (p-NP), which can quench the fluorescent signal through the inner-filter effect. The as-prepared CeO@PDA@AuNCs-MIPs nanozyme-based fluorescence method for MP detection displayed superior analytical performances with wide linearities range of 0.45-125 nM and the detection limit of 0.15 nM. Furthermore, the designed method offers satisfactory practical application ability. The developed method is simple and effective for the in-field detection.
PubMed: 38879946
DOI: 10.1016/j.talanta.2024.126434 -
Laboratory Animal Research Jun 2024The aim of the study was to develop a technique for quantitative determination of rat urine metabolites by HPLC-MS/MS, which can be used to search for biomarkers of...
BACKGROUND
The aim of the study was to develop a technique for quantitative determination of rat urine metabolites by HPLC-MS/MS, which can be used to search for biomarkers of acute intoxication with organophosphates (OPs).
RESULTS
The content of metabolites in the urine of rats exposed to a single dose of paraoxon (POX1x); interval, twice daily administration of paraoxon (POX2x); exposure to 2-(o-cresyl)-4H-1, 3, 2-benzodioxaphosphorin-2-oxide and paraoxon (CBPOX) was investigated. New data were obtained on the content in the urine of intact rats as well as rats in 3 models of OP poisoning: 3-methylhistidine, threonine, creatine, creatinine, lactic acid, acetylcarnitine, inosine, hypoxanthine, adenine, 3-hydroxymethyl-butyrate and 2-hydroxymethyl-butyrate.
CONCLUSIONS
The proposed assay procedure is a simple and reliable tool for urine metabolomic studies. Within 1-3 days after OP exposure in all three models of acute intoxication, the concentration of metabolites in rat urine, with the exception of adenine, changes similarly and symmetrically, regardless of the method of poisoning modeling, in all three models of acute intoxication. Further studies are needed to determine the specificity and reliability of using urinary metabolite concentration changes as potential biomarkers of acute organophosphate intoxication.
PubMed: 38845041
DOI: 10.1186/s42826-024-00209-3 -
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 -
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 -
Biomolecules May 2024Olesoxime, a cholesterol derivative with an oxime group, possesses the ability to cross the blood-brain barrier, and has demonstrated excellent safety and tolerability...
Olesoxime, a cholesterol derivative with an oxime group, possesses the ability to cross the blood-brain barrier, and has demonstrated excellent safety and tolerability properties in clinical research. These characteristics indicate it may serve as a centrally active ligand of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), whose disruption of activity with organophosphate compounds (OP) leads to uncontrolled excitation and potentially life-threatening symptoms. To evaluate olesoxime as a binding ligand and reactivator of human AChE and BChE, we conducted kinetic studies with the active metabolite of insecticide parathion, paraoxon, and the warfare nerve agents sarin, cyclosarin, tabun, and VX. Our results showed that both enzymes possessed a binding affinity for olesoxime in the mid-micromolar range, higher than the antidotes in use (i.e., 2-PAM, HI-6, etc.). While olesoxime showed a weak ability to reactivate AChE, cyclosarin-inhibited BChE was reactivated with an overall reactivation rate constant comparable to that of standard oxime HI-6. Moreover, in combination with the oxime 2-PAM, the reactivation maximum increased by 10-30% for cyclosarin- and sarin-inhibited BChE. Molecular modeling revealed productive interactions between olesoxime and BChE, highlighting olesoxime as a potentially BChE-targeted therapy. Moreover, it might be added to OP poisoning treatment to increase the efficacy of BChE reactivation, and its cholesterol scaffold could provide a basis for the development of novel oxime antidotes.
Topics: Humans; Butyrylcholinesterase; Acetylcholinesterase; Ligands; Oximes; Cholinesterase Reactivators; Cholinesterase Inhibitors; Cholestenones; Kinetics; Sarin; GPI-Linked Proteins; Antidotes; Cholesterol; Organophosphorus Compounds
PubMed: 38785995
DOI: 10.3390/biom14050588