Efficacy of an organophosphorus hydrolase enzyme (OpdA) in human serum and minipig models of organophosphorus insecticide poisoning

Therapeutic potential of 2S-hesperidin against the hepatotoxic effects of dichlorvos in rats

Dichlorvos (DDVP) is an organophosphate insecticide that enhances food production and repels disease vectors. However, it provokes cytotoxicity. 2S-hesperidin (2S-HES) is a potent antioxidant, anti-inflammatory, and anti-lipidemic flavanone. Regardless, the 2S-HES impact on DDVP-occupied hepatic injury remains fuzzy. We evaluated the therapeutic potential of 2S-HES in a rat model of DDVP-elicited hepatic intoxication. Forty-two rats were randomly allotted to seven groups (n = 6/condition): control, DDVP (8 mg kg⁻1day⁻1), DDVP with 2S-HES (50 and 100 mg kg⁻1day⁻1), DDVP with atropine, and 2S-HES alone (50 and 100 mg kg⁻1day⁻1). DDVP was administered orally for 7 days, followed by 14 days of 2S-HES chemotherapy. 2S-HES intervention partially mitigated DDVP-triggered alterations in leakage enzymes (ALT, AST, ALP, LDH-5), total protein, albumin, globulin, bilirubin, electrolytes, ion-transporters, lipid profiles, and HMG-CoA reductase. Furthermore, 2S-HES partially reversed DDVP-provoked increases in hepatic H₂O₂, NO, and malondialdehyde; transposed DDVP-mediated decreased liver GSH amount and activities of GST, SOD, catalase, and GPx; attenuated DDVP-triggered upregulated NF-κB-p65 and caspase-3; and abated DDVP-engendered repressed interleukin-10 mRNA expression. Cytoarchitectural analyses authenticated the 2-HES reduction in DDVP-evoked hepatocellular vacuolation. Altogether, 2S-HES elicited promising alternative or adjunctive therapy for partially mitigating DDVP-incited hepatic injury by attenuating leakage enzymes, ionoregulatory disruptions, ion pump inhibition, dyslipidemias, oxidative stress, inflammation, and apoptosis.

Preparation of surface molecularly imprinted polymers with Fe3O4/ZIF-8 as carrier for detection of Dimethoate in cabbage

In this study, molecularly imprinted polymers (MIPs) were prepared for the specific recognition of organophosphorus pesticides and a rapid, efficient and simple method was established for the detection of dimethoate (DIT) in food samples. Fe3O4 magnetic nanoparticles were synthesized by co-precipitation, and Fe3O4/ZIF-8 complexes were prepared by a modified in-situ polymerization method, and then magnetic molecularly imprinted polymers (MMIPs) were prepared and synthetic route was optimized by applying density functional theory (DFT). The morphological characterization showed that the MMIPs were coarse porous spheres with an average particle size of 50 nm. The synthesized materials are highly selective for the organophosphorus pesticide dimethoate with an adsorption capacity of 461.50 mg·g-1 and are effective resistance to matrix effects. A novel method for the determination of DIT in cabbage was developed using the prepared MMIPs in combination with HPLC. The practical results showed that the method can meet the requirements for the determination of DIT in cabbage with recoveries of 85.6-121.1 % and detection limits of 0.033 μg·kg-1.

Simultaneous determination of fenthion and its metabolites in a case of fenthion self-poisoning

Fenthion (MPP) is a popular organophosphorus pesticide that acts via inhibition of the enzyme cholinesterase. It is well known that fenthion is metabolized by plants, animals and soil microorganisms to sulfone and sulfoxide by oxidation of thioether and is further metabolized by conversion of P = S to P = O (oxon). Although human fenthion poisonings sometimes occur, details of the distribution of fenthion and its metabolites within the bodies of victims are unclear. In this study, we developed and validated an approach that uses liquid chromatography coupled with electrospray ionization-tandem mass spectrometry to quantify the concentrations of fenthion and its five metabolites (MPP-sulfoxide, MPP-sulfone, MPP-oxon, MPP-oxon sulfoxide and MPP-oxon sulfone) in the fluids [blood, cerebral spinal fluid (CSF) and urine] of a human cadaver. The calibration curves were linear in the concentration range 5-200 ng/mL. Our method allowed for repeatable and accurate quantification with intra- and inter-assay coefficients of variation smaller than 8.6% and 11.0%, respectively, for each target compound. We used the developed method to measure the fenthion concentration in the blood of a dead victim of fenthion poisoning and found the concentration to be in the comatose-fatal range. In addition, we detected for the first time fenthion and all five fenthion metabolites in the cadaveric blood and CSF. The concentrations of the oxidized forms of fenthion, including MPP-sulfone and MPP-sulfoxide, were higher in CSF than in the blood.

Malathion or diazinon exposure and male reproductive toxicity: a systematic review of studies performed with rodents

Malathion and diazinon are pesticides commonly used in agriculture to avoid insects that damage crops; however, they may cause impairment to the male genital system of exposed humans. The present work carried out a systematic review of the literature concerning the primary studies that assessed the reproductive effects resulting from male rats and mice exposed to malathion or diazinon. The search for articles was performed on the databases PubMed, LILACS, Scopus, and SciELO, using different combinations of the search terms "malathion," "diazinon," "mice," "rats," "male reproduction," "fertility," and "sperm," followed by the Boolean operators AND or OR. The results obtained indicate that both pesticides act as reproductive toxicants by reducing sperm quality, diminishing hormonal concentrations, inducing increased oxidative stress, and provoking histopathological damage in reproductive organs. Then, the exposure to malathion and diazinon may provoke diminished levels of testosterone by increasing acetylcholine stimulation in the testis through muscarinic receptors, thus, providing a reduction in steroidogenic activity in Leydig cells, whose effect is related to lower levels of testosterone in rodents, and consequently, it is associated with decreased fertility. Considering the toxic effects on the male genital system of rodents and the possible male reproductive toxicity in humans, it is recommended the decreased use of these pesticides and their replacement for others that show no or few toxic effects for non-target animals.

Sodium-Alginate-Functionalized Silver Nanoparticles for Colorimetric Detection of Dimethoate

Sodium alginate (SA) was used to functionalize the surfaces of silver nanoparticles (AgNPs) to form SA-AgNPs for sensing dimethoate with a rapid and sensitive visual readout. UV-Vis spectrophotometry, Fourier transform infrared spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and zeta potential measurements were used to characterize SA-AgNPs that were synthesized under the ideal conditions. SA-AgNPs were spherical with an average size of 14.6 nm. The stability of SA-AgNPs was investigated with changes in pH, salinity, and storage time. This colorimetric assay of dimethoate relied on the change in the absorption ratio (A₄₇₅/A₄₀₀) of SA-AgNPs, resulting in their aggregation caused by dimethoate, leading to a visual change for SA-AgNPs from yellow to pale yellow. As a result, the absorption ratio (A₄₇₅/A₄₀₀) of SA-AgNPs showed good linearity in the range of 0.05 to 2.0 ppm (R² = 0.9986) with a limit of detection (LOD) of 30 ppb. Adding other pesticides did not significantly change the absorption ratio of SA-AgNPs, indicating its high selectivity as a colorimetric assay. The sensor was successfully used to detect dimethoate in actual water samples.

Lung injury caused by aspiration of organophosphorus insecticide and gastric contents in pigs

INTRODUCTION

Patients who require mechanical ventilation after self-poisoning with ingested organophosphorus (OP) insecticides often die. Aspiration of stomach contents may contribute to lung injury and lethality. This study was designed to assess the severity of direct and indirect pulmonary injury created by pulmonary instillation of mixtures of OP insecticide, solvent (Solv) and porcine gastric juice (GJ) compared to controls.

METHODS

Terminally anaesthetised minipigs (groups n = 5) were exposed to sham bronchoscopy or given mixtures (0.5 mL/kg) of: saline, GJ, OP insecticide and GJ (OP + GJ), or Solv and GJ (Solv + GJ), placed into the right lung, and monitored for 48 h. Lung injury was assessed through analysis of bronchoalveolar lavage fluid (BALF), computed tomography and histopathology.

RESULTS

OP + GJ created a direct lung injury consisting of neutrophil infiltration, oedema and haemorrhage, as well as indirect injury to the other lung. OP + GJ directly-injured lung parenchyma had increased concentrations of BALF protein, albumin, IL-6, IL-8 and C-reactive protein (CRP) at 24 h (p < 0.05), and BALF protein, albumin and CRP at 48 h (p < 0.05), when compared with controls. Aspiration of GJ produced similar direct effects to OP + GJ but less indirect lung injury. Lung injury was less severe after Solv + GJ, for combined lung histopathology scores (vs. OP + GJ, p < 0.05) and for the proportion of directly-injured lung that was poorly/non-aerated at 48 h.

CONCLUSION

Pulmonary instillation of OP + GJ created more lung damage than controls or Solv + GJ. In patients with severe OP insecticide poisoning and reduced consciousness, early airway protection is likely to reduce pulmonary damage.

CON: Oximes should be used routinely in organophosphorus insecticide poisoning

Organophosphorus (OP) insecticide poisoning causes respiratory failure due to acetylcholinesterase (AChE) inhibition. The AChE reactivating antidote pralidoxime was developed in the 1950s and soon noted to benefit patients occupationally poisoned with the highly potent OP insecticide parathion. Routine use of pralidoxime and other oximes such as obidoxime then became widely recommended. However, nearly all severe cases of OP poisoning now result from self-poisoning with large volumes of less potent (WHO hazard class Ib and II) insecticides and co-formulated solvents. Unfortunately, oxime clinical trials have never shown benefit from their use for these patients, and some have shown that pralidoxime may be associated with harm, including increased mortality. Oximes should not be used routinely for the care of OP insecticide poisoned patients until translational and clinical studies have identified a safe and effective oxime regimen and identified the patients who benefit.

Selected Ion Flow Tube-Mass Spectrometry (SIFT-MS) as an Alternative to Gas Chromatography/Mass Spectrometry (GC/MS) for the Analysis of Cyclohexanone and Cyclohexanol in Plasma

Self-poisoning with professional agricultural pesticide products is responsible for about 20% of global suicide, with most cases occurring in South Asia and China. Treatment of severe poisoning involves long-term intensive clinical care and is often unsuccessful. Solvent co-formulants (such as cyclohexanone) also contribute to mortality themselves or via more toxic metabolic products (such as cyclohexanol). Faster detection of co-formulants could aid earlier identification of pesticide poisoning and faster intervention, reducing mortality. Conventional analysis of volatiles in blood uses headspace (HS)-GC/MS. This paper evaluates SIFT-MS, a direct MS technique that provides higher sample throughput than GC/MS, as a potential tool for cyclohexanone and cyclohexanol analysis in plasma. Both instruments were calibrated using a conventional approach prior to analysis of each porcine plasma sample on both instruments. Comparative data were evaluated using Bland-Altman plots, demonstrating that the techniques were in good agreement. Compared with GC/MS, SIFT-MS provides fourfold higher sample throughput and shows great promise as an alternative analytical tool.

Organophosphorus pesticide tolerance of transgenic Arabidopsis thaliana by bacterial ophB gene encode organophosphorus hydrolase

Organophosphate hydrolase (OphB) gene from Pseudomonas sp. was transferred into Arabidopsis plants to observe the bioremediation ability and tolerance level of the transgenic plant to organophosphate pesticides contaminants. Gene transfer was observed by PCR of the transgenic Arabidopsis plants' genomic DNA. Expression of ophB gene and protein levels in the transgenic Arabidopsis plants was observed by western blot analysis. The transgenic plants were resistant and tolerant to chlorpyrifos (an organophosphate pesticide), as evidenced by a toxicity test, where the transgenic plants produced greater shoot and root biomass than that of wild type plants. The fresh weight of transgenic Arabidopsis plants' did not reduced significantly till 400 ppm chlorpyrifos treatment, but fresh weight of wild type Arabidopsis plants' significantly reduced by the application of 100 ppm chlorpyrifos. Moreover, in 600 ppm chlorpyrifos liquid culture, transgenic Arabidopsis plants' produced 1.34 g biomass from 100 seeds, but wild type Arabidopsis plants' produced only 0.24 g biomass from 100 seeds. This study indicates that transgenic Arabidopsis plants having ophB gene increase the tolerance level of organophosphate pesticides.

Overview of a bioremediation tool: organophosphorus hydrolase and its significant application in the food, environmental, and therapy fields

In the past decades, the organophosphorus compounds had been widely used in the environment and food industries as pesticides. Owing to the life-threatening and long-lasting problems of organophosphorus insecticide (OPs), an effective detection and removal of OPs have garnered growing attention both in the scientific and practical fields in recent years. Bacterial organophosphorus hydrolases (OPHs) have been extensively studied due to their high specific activity against OPs. OPH could efficiently hydrolyze a broad range of substrates both including the OP pesticides and some nerve agents, suggesting a great potential for the remediation of OPs. In this review, the microbial identification, molecular modification, and practical application of OPHs were comprehensively discussed.Key points• Microbial OPH is a significant bioremediation tool against OPs.• Identification and molecular modification of OPH was discussed in detail.• The applications of OPH in food, environmental, and therapy fields are presented.

Mitigation of organophosphorus insecticides from environment: Residual detoxification by bioweapon catalytic scavengers

Organophosphorus insecticides (OPIs) have low persistence and are easily biodegradable in nature. The United States and India are the major countries producing OPIs of about 25% and 17% of the world, respectively. OPIs commonly used for agricultural practices occupy a major share in the global market, which leads to the increasing contamination of OPIs residues in various food chains. To overcome this issue, an enzymatic degradation method has been approved by several environmental toxic, and controlling agencies, including United States Environmental Protection Agency (USEPA). Different catalytic enzymes have been isolated and identified from various microbial sources to neutralize the toxic pesticides and/or insecticides. In this review, we have gathered information on OPIs biotransformation and their residual toxicity in the environment. Particularly, it focuses on OPIs degrading enzymes such as chlorpyrifos hydrolase, diisopropylfluorophosphatase, organophosphate acid anhydrolase, organophosphate hydrolases, and phosphotriesterases like lactonasesspecific activity either P-O link group type or P-S link group of pesticides. To summarize, the catalytic degradation of organophosphorus insecticides is not only profitable but also environmentally friendly. Hence, the enzymatic catalyst is an ultimate and super bio-weapon to mitigate or decontaminate various OPIs residues in both terrestrial and aqueous environments.

Transitioning from Oxime to the Next Potential Organophosphorus Poisoning Therapy Using Enzymes

For years, organophosphorus poisoning has been a major concern of health problems throughout the world. An estimated 200,000 acute pesticide poisoning deaths occur each year, many in developing countries. Apart from the agricultural pesticide poisoning, terrorists have used these organophosphorus compounds to attack civilian populations in some countries. Recent misuses of sarin in the Syrian conflict had been reported in 2018. Since the 1950s, the therapy to overcome this health problem is to utilize a reactivator to reactivate the inhibited acetylcholinesterase by these organophosphorus compounds. However, many questions remain unanswered regarding the efficacy and toxicity of this reactivator. Pralidoxime, MMB-4, TMB-4, obidoxime, and HI-6 are the examples of the established oximes, yet they are of insufficient effectiveness in some poisonings and only a limited spectrum of the different nerve agents and pesticides are being covered. Alternatively, an option in the treatment of organophosphorus poisoning that has been explored is through the use of enzyme therapy. Organophosphorus hydrolases are a group of enzymes that look promising for detoxifying organophosphorus compounds and have recently gained much interest. These enzymes have demonstrated remarkable protective and antidotal value against some different organophosphorus compounds in vivo in animal models. Apart from that, enzyme treatments have also been applied for decontamination purposes. In this review, the restrictions and obstacles in the therapeutic development of oximes, along with the new strategies to overcome the problems, are discussed. The emerging interest in enzyme treatment with its advantages and disadvantages is described as well.

Poisoning by organophosphorus nerve agents and pesticides: An overview of the principle strategies and current progress of mass spectrometry-based procedures for verification

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Evidence of poisoning with organophosphorus (OP) nerve agents requires biomedical verification.

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OP nerve agents undergo common biotransformation pathways producing valuable biomarkers.

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Internationally accepted methods target remaining poison, hydrolysis products and protein-adducts.

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Mass spectrometry-based methods provide optimum selectivity and sensitivity for identification.

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Methods, strategies, current proceedings, quality criteria and real cases of poisoning are presented.

Intoxication by organophosphorus (OP) poisons, like nerve agents and pesticides, is characterized by the life-threatening inhibition of acetylcholinesterase (AChE) caused by covalent reaction with the serine residue of the active site of the enzyme (phosphylation). Similar reactions occur with butyrylcholinesterase (BChE) and serum albumin present in blood as dissolved proteins. For forensic purposes, products (adducts) with the latter proteins are highly valuable long-lived biomarkers of exposure to OP agents that are accessible by diverse mass spectrometric procedures. In addition, the evidence of poison incorporation might also succeed by the detection of remaining traces of the agent itself, but more likely its hydrolysis and/or enzymatic degradation products. These relatively short-lived molecules are distributed in blood and tissue, and excreted via urine. This review presents the mass spectrometry-based methods targeting the different groups of biomarkers in biological samples, which are already internationally accepted by the Organisation for the Prohibition of Chemical Weapons (OPCW), introduces novel approaches in the field of biomedical verification, and outlines the strict quality criteria that must be fulfilled for unambiguous forensic analysis.