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Annals of the New York Academy of... Aug 2016Accidental or intentional exposures to parathion, an organophosphorus (OP) pesticide, can cause severe poisoning in humans. Parathion toxicity is dependent on its... (Review)
Review
Accidental or intentional exposures to parathion, an organophosphorus (OP) pesticide, can cause severe poisoning in humans. Parathion toxicity is dependent on its metabolism by the cytochrome P450 (CYP) system to paraoxon (diethyl 4-nitrophenyl phosphate), a highly poisonous nerve agent and potent inhibitor of acetylcholinesterase. We have been investigating inhibitors of CYP-mediated bioactivation of OPs as a method of preventing or reversing progressive parathion toxicity. It is well recognized that NADPH-cytochrome P450 reductase, an enzyme required for the transfer of electrons to CYPs, mediates chemical redox cycling. In this process, the enzyme diverts electrons from CYPs to support chemical redox cycling, which results in inhibition of CYP-mediated biotransformation. Using menadione as the redox-cycling chemical, we discovered that this enzymatic reaction blocks metabolic activation of parathion in rat and human liver microsomes and in recombinant CYPs important to parathion metabolism, including CYP1A2, CYP2B6, and CYP3A4. Administration of menadione to rats reduces metabolism of parathion, as well as parathion-induced inhibition of brain cholinesterase activity. This resulted in inhibition of parathion neurotoxicity. Menadione has relatively low toxicity and is approved by the Food and Drug Administration for other indications. Its ability to block parathion metabolism makes it an attractive therapeutic candidate to mitigate parathion-induced neurotoxicity.
Topics: Animals; Cholinesterase Inhibitors; Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme System; Drug Delivery Systems; Humans; Insecticides; Organophosphate Poisoning; Parathion; Vitamin K 3
PubMed: 27441453
DOI: 10.1111/nyas.13156 -
Journal of Toxicology 2020Organophosphorus compounds are extensively used worldwide as pesticides which cause great hazards to human health. Nerve agents, a subcategory of the organophosphorus... (Review)
Review
Organophosphorus compounds are extensively used worldwide as pesticides which cause great hazards to human health. Nerve agents, a subcategory of the organophosphorus compounds, have been produced and used during wars, and they have also been used in terrorist activities. These compounds possess physiological threats by interacting and inhibiting acetylcholinesterase enzyme which leads to the cholinergic crisis. After a general introduction, this review elucidates the mechanisms underlying cholinergic and noncholinergic effects of organophosphorus compounds. The conceivable treatment strategies for organophosphate poisoning are different types of bioscavengers which include stoichiometric, catalytic, and pseudocatalytic. The current research on the promising treatments specifically the catalytic bioscavengers including several wild-type organophosphate hydrolases such as paraoxonase and phosphotriesterase, phosphotriesterase-like lactonase, methyl parathion hydrolase, organophosphate acid anhydrolase, diisopropyl fluorophosphatase, human triphosphate nucleotidohydrolase, and senescence marker protein has been widely discussed. Organophosphorus compounds are reported to be the nonphysiological substrate for many mammalian organophosphate hydrolysing enzymes; therefore, the efficiency of these enzymes toward these compounds is inadequate. Hence, studies have been conducted to create mutants with an enhanced rate of hydrolysis and high specificity. Several mutants have been created by applying directed molecular evolution and/or targeted mutagenesis, and catalytic efficiency has been characterized. Generally, organophosphorus compounds are chiral in nature. The development of mutant enzymes for providing superior stereoselective degradation of toxic organophosphorus compounds has also been widely accounted for in this review. Existing enzymes have shown limited efficiency; hence, more effective treatment strategies have also been critically analyzed.
PubMed: 33029136
DOI: 10.1155/2020/3007984 -
Environment International Jan 2020The present study reports one of the few cases in which organophosphate (OP) and pyrethroid (PYR) pesticide human exposure is evaluated in family contexts by the...
The present study reports one of the few cases in which organophosphate (OP) and pyrethroid (PYR) pesticide human exposure is evaluated in family contexts by the analysis of mother/child pair samples. Urinary concentrations of 6 organic metabolites of organophosphates and 2 pyrethroids were measured in mothers and their 7-to 8-year-old children (n = 168) in a general population from the central area of Slovenia. The results were adjusted for specific gravity and creatinine. The most abundant OP metabolite in children was 4-nitrophenol (PNP) (median 0.7 ng/ml) and in mothers (0.45 ng/ml), representing parathion exposure. 3-Phenoxibenzoic acid (3-PBA) (0.26 ng/ml), the general metabolite of pyrethroids, and 3,5,6-trichloro-2-pyridinol (TCPY) (0.16 ng/ml; chlorpyriphos) were the second most abundant compounds in children and mothers, respectively. The geometric mean specific gravity adjusted concentrations of OPs and PYRs were statistically significantly higher in children than in their mothers (between 3% and 24% higher), with the exception of TCPY (26% lower). All OP and PYR metabolites found in higher concentration in children showed significant positive correlations with the metabolite concentrations found in the mothers (p < 0.05 and 0.01), involving the fact that higher maternal concentrations were associated with higher children levels. These differential mother-children distributions and significant correlations were observed for the 2 types of pesticides studied, OPs and PYRs, which have different chemical properties. This agreement is consistent with the incorporation of the pesticides because of the general activities developed in the family context, instead of pesticide-dependent specific inputs. Comparison of the estimated daily intakes with the acceptable daily intakes of all detected metabolites revealed no significant risk of adverse health effects from exposure to these pesticides.
Topics: Attention; Child; Environmental Exposure; Female; Humans; Mothers; Organophosphates; Pesticides; Pyrethrins
PubMed: 31706197
DOI: 10.1016/j.envint.2019.105264 -
Neurotoxicology Sep 2015Parathion and chlorpyrifos are organophosphorus insecticides (OPs) that elicit acute toxicity by inhibiting acetylcholinesterase (AChE). The endocannabinoids (eCBs,... (Comparative Study)
Comparative Study
Parathion and chlorpyrifos are organophosphorus insecticides (OPs) that elicit acute toxicity by inhibiting acetylcholinesterase (AChE). The endocannabinoids (eCBs, N-arachidonoylethanolamine, AEA; 2-arachidonoylglycerol, 2AG) are endogenous neuromodulators that regulate presynaptic neurotransmitter release in neurons throughout the central and peripheral nervous systems. While substantial information is known about the eCBs, less is known about a number of endocannabinoid-like metabolites (eCBLs, e.g., N-palmitoylethanolamine, PEA; N-oleoylethanolamine, OEA). We report the comparative effects of parathion and chlorpyrifos on AChE and enzymes responsible for inactivation of the eCBs, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), and changes in the eCBs AEA and 2AG and eCBLs PEA and OEA, in rat striatum. Adult, male rats were treated with vehicle (peanut oil, 2 ml/kg, sc), parathion (27 mg/kg) or chlorpyrifos (280 mg/kg) 6-7 days after surgical implantation of microdialysis cannulae into the right striatum, followed by microdialysis two or four days later. Additional rats were similarly treated and sacrificed for evaluation of tissue levels of eCBs and eCBLs. Dialysates and tissue extracts were analyzed by LC-MS/MS. AChE and FAAH were extensively inhibited at both time-points (85-96%), while MAGL activity was significantly but lesser affected (37-62% inhibition) by parathion and chlorpyrifos. Signs of toxicity were noted only in parathion-treated rats. In general, chlorpyrifos increased eCB levels while parathion had no or lesser effects. Early changes in extracellular AEA, 2AG and PEA levels were significantly different between parathion and chlorpyrifos exposures. Differential changes in extracellular and/or tissue levels of eCBs and eCBLs could potentially influence a number of signaling pathways and contribute to selective neurological changes following acute OP intoxications.
Topics: Acetylcholinesterase; Amides; Amidohydrolases; Animals; Arachidonic Acids; Chlorpyrifos; Cholinesterase Inhibitors; Corpus Striatum; Endocannabinoids; Ethanolamines; Glycerides; Lipid Metabolism; Male; Monoacylglycerol Lipases; Oleic Acids; Palmitic Acids; Parathion; Rats; Rats, Sprague-Dawley; Tandem Mass Spectrometry; Time Factors
PubMed: 26215119
DOI: 10.1016/j.neuro.2015.07.006 -
Environmental Research Nov 2022Organophosphate (OP) and pyrethroid pesticides (PYR) are extensively used in agriculture, resulting in higher exposures among farmworkers. The present study reports the...
Organophosphate (OP) and pyrethroid pesticides (PYR) are extensively used in agriculture, resulting in higher exposures among farmworkers. The present study reports the occurrence of 8 urinary OP and PYR metabolites in a sample of farmworkers and residents from Sucs (n = 87), a rural township in North West Catalonia (Spain). The aim of the present study was to examine differences in urinary pesticide metabolite concentrations between occupationally-exposed (farmworkers; n = 45) and environmentally-exposed subjects (n = 42) and to assess the relationship between pesticide's exposures and occupational activities in a real-case scenario. Six OP and two PYR metabolites have been investigated, urine samples were extracted using SPE extraction and analyzed by UPLC-MS/MS. Three OP metabolites were commonly detectable in urine, namely TCPY (metabolite of chlorpyrifos), PNP (parathion) and DEAMPY (pirimiphos). Regarding pyrethroids, the two analyzed metabolites, 3-PBA and 4F-3-PBA, were detected in a high proportion of urine samples. Differences in concentrations between both groups were statistically significant for TCPY and 4F-3-PBA (Mann-Whitney U Test for independent groups, p < 0.05). In the case of TCPY, the concentrations were higher among the farmworkers, which is consistent with their occupational activity. The small differences found in DEAMPY, PNP, 3-PBA or even the significant higher concentrations of 4F-3-PBA among rural population suggest a general exposure to these compounds, even in those who do not carry an occupational activity. Specific personal protective equipment (PPE) among farmworkers, such as the use of gloves and mask during mixing, showed a decrease in the exposure levels, although the differences were not statistically significant. However, a positive association was found between the use of a cap during mixing (for PNP and 3-PBA) and during application (only for 3-PBA). However, this piece of cloth is mainly used for sun protection, and when not cleaned after the handling of pesticides, it might represent a continuous source of exposure through dermal contact. Farmworkers using tractors with cabin had statistically significant lower concentrations of DEAMPY than those using a tractor without cabin. The previous results suggest that occupational protections should be encouraged among farmworkers and other potential workers handling with pesticides.
Topics: Agriculture; Chlorpyrifos; Chromatography, Liquid; Humans; Occupational Exposure; Pesticides; Pyrethrins; Rural Population; Tandem Mass Spectrometry
PubMed: 36030920
DOI: 10.1016/j.envres.2022.114186 -
Biochimica Et Biophysica Acta Jan 2013Phosphotriesters are one class of highly toxic synthetic compounds known as organophosphates. Wide spread usage of organophosphates as insecticides as well as nerve... (Review)
Review
Phosphotriesters are one class of highly toxic synthetic compounds known as organophosphates. Wide spread usage of organophosphates as insecticides as well as nerve agents has lead to numerous efforts to identify enzymes capable of detoxifying them. A wide array of enzymes has been found to have phosphotriesterase activity including phosphotriesterase (PTE), methyl parathion hydrolase (MPH), organophosphorus acid anhydrolase (OPAA), diisopropylfluorophosphatase (DFP), and paraoxonase 1 (PON1). These enzymes differ widely in protein sequence and three-dimensional structure, as well as in catalytic mechanism, but they also share several common features. All of the enzymes identified as phosphotriesterases are metal-dependent hydrolases that contain a hydrophobic active site with three discrete binding pockets to accommodate the substrate ester groups. Activation of the substrate phosphorus center is achieved by a direct interaction between the phosphoryl oxygen and a divalent metal in the active site. The mechanistic details of the hydrolytic reaction differ among the various enzymes with both direct attack of a hydroxide as well as covalent catalysis being found. This article is part of a Special Issue entitled: Chemistry and mechanism of phosphatases, diesterases and triesterases.
Topics: Animals; Aryldialkylphosphatase; Binding Sites; Catalysis; Catalytic Domain; Cations, Divalent; Humans; Metals; Models, Chemical
PubMed: 22561533
DOI: 10.1016/j.bbapap.2012.04.004 -
Journal of Medical Toxicology :... Dec 2018The gap between the number of patients on transplant waiting lists and patients receiving transplants is growing. Use of organs from donors who have died following... (Review)
Review
INTRODUCTION
The gap between the number of patients on transplant waiting lists and patients receiving transplants is growing. Use of organs from donors who have died following pesticide exposure remains controversial. This study reviews the literature related to transplantation from this group.
METHODS
A literature search was undertaken on PubMed using the following keywords: 'insecticide', 'pesticide', 'rodenticide', 'organophosphate', 'carbamate', 'paraquat', 'poisoning', 'toxicity', 'overdose', 'intoxication', 'ingestion', 'organ donation or procurement', 'transplant', 'allograft transplant', and 'expanded criteria organ donation'; 21 specific pesticides/insecticides were also added to the search; the indexes for EAPCCT/NACCT meeting abstracts 2008-2017 were also searched. Identified publications were reviewed and if described human donation/transplantation of ≥ 1 solid organ(s), the following was extracted: (i) compound(s) ingested; (ii) donor demographics; (iii) organ(s) transplanted; and (iv) graft function at follow-up.
RESULTS
Ten papers were identified describing 20 fatalities (1999-2017) related to the following pesticide exposures: organophosphate, 8 cases; aldicarb, 4; paraquat, 3; parathion, 1; malathion, 1; carbofuran/carbamate, 1; carbamate, 1; and brodifacoum, 1 and no further cases were identified from EAPCCT/NACCT abstracts. Donors were aged 12-50 (25.9 ± 11.9) years. Forty-four organs were transplanted: 28 kidneys, 7 livers, 6 corneas, and 3 hearts. Forty recipients had outcome reported: 3 (7.5%) patients died, 3 (7.5%) had graft failure/dysfunction and 34 (85.0%) had good graft function. Overall survival with good function was 96%, 71%, 83%, and 67% for kidneys, livers, corneas and hearts respectively.
CONCLUSION
Review of the published literature suggests that solid organ donation following exposure to a pesticide is associated with good short-to-medium-term graft organ function following transplantation, particularly for transplanted kidneys and corneas.
Topics: Humans; Organ Transplantation; Pesticides; Tissue Donors; Treatment Outcome
PubMed: 29987646
DOI: 10.1007/s13181-018-0673-5