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ACS Applied Nano Materials Dec 2022Nanoscale cerium-bismuth oxides/oxynitrates were prepared by a scalable low-temperature method at ambient pressure using water as the sole solvent. Solid solutions were...
Nanoscale cerium-bismuth oxides/oxynitrates were prepared by a scalable low-temperature method at ambient pressure using water as the sole solvent. Solid solutions were formed up to a 1:1 Ce/Bi molar ratio, while at higher doping levels, bismuth oxynitrate photocatalysts with a pronounced layered structure were formed. Bismuth caused significant changes in the structure and surface properties of nanoceria, such as the formation of defects, oxygen-containing surface groups, and Lewis and Brønsted acid sites. The prepared bifunctional adsorbents/photocatalysts were efficient in the removal of toxic organophosphate (methyl paraoxon) from water by reactive adsorption followed by photocatalytic decomposition of the parent compound and its degradation product (-nitrophenol). Bi-doped ceria also effectively adsorbed and photodegraded the endocrine disruptors bisphenols A and S and outperformed pure ceria and the P25 photocatalyst in terms of efficiency, durability, and long-term stability. The very low toxicity of Bi-nanoceria to mammalian cells, aquatic organisms, and bacteria has been demonstrated by comprehensive in vivo/in vitro testing, which, in addition to its simple "green" synthesis, high activity, and durability, makes Bi-doped ceria promising for safe use in abatement of toxic chemicals.
PubMed: 36583119
DOI: 10.1021/acsanm.2c03926 -
International Journal of Molecular... Jul 2019In this study, silica-coated magnetic nanoparticles (SiMNPs) with isocyanatopropyltriethoxysilane as a metal-chelating ligand were prepared for the immobilization of...
In this study, silica-coated magnetic nanoparticles (SiMNPs) with isocyanatopropyltriethoxysilane as a metal-chelating ligand were prepared for the immobilization of His-tagged prolidase (His-PepQ). Under one-hour coupling, the enzyme-loading capacity for the Ni-functionalized SiMNPs (NiNTASiMNPs) was 1.5 mg/mg support, corresponding to about 58.6% recovery of the initial activity. Native and enzyme-bound NiNTASiMNPs were subsequently characterized by transmission electron microscopy (TEM), superparamagnetic analysis, X-ray diffraction, and Fourier transform infrared (FTIR) spectroscopy. As compared to free enzyme, His-EcPepQ@NiNTASiMNPs had significantly higher activity at 70 °C and pH ranges of 5.5 to 10, and exhibited a greater stability during a storage period of 60 days and could be recycled 20 times with approximately 80% retention of the initial activity. The immobilized enzyme was further applied in the hydrolysis of two different organophosphorus compounds, dimethyl -nitrophenyl phosphate (methyl paraoxon) and diethyl -nitrophenyl phosphate (ethyl paraoxon). The experimental results showed that methyl paraoxon was a preferred substrate for His-PepQ and the kinetic behavior of free and immobilized enzymes towards this substance was obviously different. Taken together, the immobilization strategy surely provides an efficient means to deposit active enzymes onto NiNTASiMNPs for His-PepQ-mediated biocatalysis.
Topics: Chelating Agents; Dipeptidases; Hydrolysis; Ions; Magnetite Nanoparticles; Metals; Organophosphorus Compounds; Spectroscopy, Fourier Transform Infrared
PubMed: 31344929
DOI: 10.3390/ijms20153625 -
International Journal of Molecular... Oct 2020Antidotes against organophosphates often possess physicochemical properties that mitigate their passage across the blood-brain barrier. Cucurbit[7]urils may be...
Antidotes against organophosphates often possess physicochemical properties that mitigate their passage across the blood-brain barrier. Cucurbit[7]urils may be successfully used as a drug delivery system for bisquaternary oximes and improve central nervous system targeting. The main aim of these studies was to elucidate the relationship between cucurbit[7]uril, oxime K027, atropine, and paraoxon to define potential risks or advantages of this delivery system in a complex in vivo system. For this reason, in silico (molecular docking combined with umbrella sampling simulation) and in vivo (UHPLC-pharmacokinetics, toxicokinetics; acetylcholinesterase reactivation and functional observatory battery) methods were used. Based on our results, cucurbit[7]urils affect multiple factors in organophosphates poisoning and its therapy by (i) scavenging paraoxon and preventing free fraction of this toxin from entering the brain, (ii) enhancing the availability of atropine in the central nervous system and by (iii) increasing oxime passage into the brain. In conclusion, using cucurbit[7]urils with oximes might positively impact the overall treatment effectiveness and the benefits can outweigh the potential risks.
Topics: Animals; Atropine; Blood-Brain Barrier; Bridged-Ring Compounds; Cholinesterase Reactivators; Computer Simulation; Imidazoles; Mice; Molecular Docking Simulation; Oximes; Paraoxon; Pyridinium Compounds
PubMed: 33114215
DOI: 10.3390/ijms21217883 -
Neuropharmacology Sep 2020More frequent and widespread nerve agent attacks highlight the need for efficacious pre- and post-exposure organophosphate (OP) counter-measures to protect military and... (Review)
Review
More frequent and widespread nerve agent attacks highlight the need for efficacious pre- and post-exposure organophosphate (OP) counter-measures to protect military and civilian populations. Because of critical targeting of acetylcholinesterase (AChE) in the CNS by OPs, a pre-treatment candidate for preventing/reducing poisoning will be a broadly acting molecule that scavenges OPs in blood before they reach their physiological targets. Prophylactic human butyrylcholinesterase (HuBChE), the leading pretreatment candidate, has been shown to protect against multiple LD's of nerve agents in rodents, macaques, and minipigs. This review describes the development of a HuBChE bioscavenger pretreatment from early proof-of-concept studies to pre-clinical studies with the native injectable enzyme and the development of aerosolized forms of recombinant enzyme, which can be delivered by inhalation nebulizer devices, to effect protection against inhaled OP nerve agents and insecticides. Early animal studies utilized parenteral exposure. However, lungs are the portal of entry for most volatile OP vapors and represent the major means of OP intoxication. In this regard, pretreat-ment with 7.5 mg/kg of HuBChE by IM injection protected minipigs against lethal sarin vapor and prevented AChE inhibition in the blood. This is similar to the five-day protection in macaques by an aerosolized rHuBChE using a nebulizer against aerosolized paraoxon (estimated to be an 8 mg/kg estimated human dose). Importantly, lethal inhaled doses of OP may be smaller relative to the same dose delivered by injection, thus reducing the protective HuBChE dose, while a combination of HuBChE and post-exposure oxime may prolong protection.
Topics: Acetylcholinesterase; Animals; Butyrylcholinesterase; Cholinesterase Inhibitors; Humans; Inhalation Exposure; Macaca; Organophosphates; Species Specificity; Swine; Swine, Miniature
PubMed: 32442543
DOI: 10.1016/j.neuropharm.2020.108150 -
Toxicology Research Jun 2020Pest management in stored grain industry is a global issue due to the development of insecticide resistance in stored grain insect pests. Excessive use of insecticides...
Pest management in stored grain industry is a global issue due to the development of insecticide resistance in stored grain insect pests. Excessive use of insecticides at higher doses poses a serious threat of food contamination and residual toxicity for grain consumers. Since the development of new pesticide incurs heavy costs, identifying an effective synergist can provide a ready and economical tool for controlling resistant pest populations. Therefore, the synergistic property of quercetin with paraoxon and tetraethyl pyrophosphate has been evaluated against the larvae and adults of (Herbst). Comparative molecular docking analyses were carried out to further identify the possible mechanism of synergism. It was observed that quercetin has no insecticidal when applied at the rate of 1.5 and 3.0 mg/g; however, a considerable synergism was observed when applied in combination with paraoxon. The comparative molecular docking analyses of CYP450 monooxygenase (CYP15A1, CYP6BR1, CYP6BK2, CYP6BK3) family were performed with quercetin, paraoxon and tetraethyl pyrophosphate which revealed considerable molecular interactions, predicting the inhibition of CYP450 isoenzyme by all three ligands. The study concludes that quercetin may be an effective synergist for organophosphate pesticides depending upon the dose and type of the compound. In addition, analyses of the structurally diversified organophosphates can effectively differentiate the organophosphates which are synergistic with quercetin.
PubMed: 32670552
DOI: 10.1093/toxres/tfaa023 -
International Journal of Molecular... Jul 2021Organophosphorus nerve agents (OPNAs) are highly toxic compounds inhibiting cholinergic enzymes in the central and autonomic nervous systems and neuromuscular junctions,...
Organophosphorus nerve agents (OPNAs) are highly toxic compounds inhibiting cholinergic enzymes in the central and autonomic nervous systems and neuromuscular junctions, causing severe intoxications in humans. Medical countermeasures and efficient decontamination solutions are needed to counteract the toxicity of a wide spectrum of harmful OPNAs including G, V and Novichok agents. Here, we describe the use of engineered OPNA-degrading enzymes for the degradation of various toxic agents including insecticides, a series of OPNA surrogates, as well as real chemical warfare agents (cyclosarin, sarin, soman, tabun, VX, A230, A232, A234). We demonstrate that only two enzymes can degrade most of these molecules at high concentrations (25 mM) in less than 5 min. Using surface assays adapted from NATO AEP-65 guidelines, we further show that enzyme-based solutions can decontaminate 97.6% and 99.4% of 10 g∙m of soman- and VX-contaminated surfaces, respectively. Finally, we demonstrate that these enzymes can degrade ethyl-paraoxon down to sub-inhibitory concentrations of acetylcholinesterase, confirming their efficacy from high to micromolar doses.
Topics: Decontamination; Enzymes; Insecticides; Nerve Agents; Organophosphorus Compounds
PubMed: 34360916
DOI: 10.3390/ijms22158152 -
Environment International May 2020Human variability in paraoxonase-1 (PON1) activities is driven by genetic polymorphisms that affect the internal dose of active oxons of organophosphorus (OP)... (Meta-Analysis)
Meta-Analysis
Human variability in paraoxonase-1 (PON1) activities is driven by genetic polymorphisms that affect the internal dose of active oxons of organophosphorus (OP) insecticides. Here, an extensive literature search has been performed to collect human genotypic frequencies (i.e. L55M, Q192R, and C-108T) in subgroups from a range of geographical ancestry and PON1 activities in three probe substrates (paraoxon, diazoxon and phenyl acetate). Bayesian meta-analyses were performed to estimate variability distributions for PON1 activities and PON1-related uncertainty factors (UFs), while integrating quantifiable sources of inter-study, inter-phenotypic and inter-individual differences. Inter-phenotypic differences were quantified using the population with high PON1 activity as the reference group. Results from the meta-analyses provided PON1 variability distributions and these can be implemented in generic physiologically based kinetic models to develop quantitative in vitro in vivo extrapolation models. PON1-related UFs in the Caucasian population were above the default toxicokinetic UF of 3.16 for two specific genotypes namely -108CC using diazoxon as probe substrate and, -108CT, -108TT, 55MM and 192QQ using paraoxon as probe substrate. However, integration of PON1 genotypic frequencies and activity distributions showed that all UFs were within the default toxicokinetic UF. Quantitative inter-individual differences in PON1 activity are important for chemical risk assessment particularly with regards to the potential sensitivity to organophosphates' toxicity.
Topics: Aryldialkylphosphatase; Bayes Theorem; Genotype; Humans; Paraoxon; Polymorphism, Genetic; Risk Assessment
PubMed: 32114288
DOI: 10.1016/j.envint.2020.105609 -
Journal of Microbiology and... Jan 2021Organophosphorus nerve agents (OPNAs), including both G- and V-type nerve agents such as sarin, soman, tabun and VX, are extremely neurotoxic organophosphorus compounds....
Organophosphorus nerve agents (OPNAs), including both G- and V-type nerve agents such as sarin, soman, tabun and VX, are extremely neurotoxic organophosphorus compounds. Catalytic bioscavengers capable of hydrolyzing OPNAs are under development because of the low protective effects and adverse side effects of chemical antidotes to OPNA poisoning. However, these bioscavengers have certain limitations for practical application, including low catalytic activity and narrow specificity. In this study, we generated a fusion-hybrid form of engineered recombinant human paraoxonase 1 (rePON1) and bacterial organophosphorus hydrolase (OPH), referred to as GV-hybrids, using a flexible linker to develop more promising catalytic bioscavengers against a broad range of OPNAs. These GV-hybrids were able to synergistically hydrolyze both G-type OPNA analogs (paraoxon: 1.7 ~ 193.7-fold, -nitrophenyl diphenyl phosphate (PNPDPP): 2.3 ~ 33.0-fold and diisopropyl fluorophosphates (DFP): 1.4 ~ 22.8-fold) and V-type OPNA analogs (demeton-Smethyl (DSM): 1.9 ~ 34.6-fold and malathion: 1.1 ~ 4.2-fold above) better than their individual enzyme forms. Among the GV-hybrid clones, the GV7 clone showed remarkable improvements in the catalytic activity toward both G-type OPNA analogs (/ (10 M min): 59.8 ± 0.06 (paraoxon), 5.2 ± 0.02 (PNPDPP) and 47.0 ± 6.0 (DFP)) and V-type OPNA analogs (/ (M min): 504.3 ± 48.5 (DSM) and 1324.0 ± 47.5 (malathion)). In conclusion, we developed GV-hybrid forms of rePON1 and bacterial OPH mutants as effective and suitable catalytic bioscavengers to hydrolyze a broad range of OPNA analogs.
Topics: Antidotes; Aryldialkylphosphatase; Catalysis; Genetic Engineering; Humans; Hydrolysis; Nerve Agents; Organophosphates; Organophosphorus Compounds; Phosphoric Triester Hydrolases; Recombinant Fusion Proteins; Substrate Specificity
PubMed: 33144547
DOI: 10.4014/jmb.2006.06044 -
Biochemistry Mar 2019Organophosphorus flame retardants are stable toxic compounds used in nearly all durable plastic products and are considered major emerging pollutants. The...
Organophosphorus flame retardants are stable toxic compounds used in nearly all durable plastic products and are considered major emerging pollutants. The phosphotriesterase from Sphingobium sp. TCM1 ( Sb-PTE) is one of the few enzymes known to be able to hydrolyze organophosphorus flame retardants such as triphenyl phosphate and tris(2-chloroethyl) phosphate. The effectiveness of Sb-PTE for the hydrolysis of these organophosphates appears to arise from its ability to hydrolyze unactivated alkyl and phenolic esters from the central phosphorus core. How Sb-PTE is able to catalyze the hydrolysis of the unactivated substituents is not known. To interrogate the catalytic hydrolysis mechanism of Sb-PTE, the pH dependence of the reaction and the effects of changing the solvent viscosity were determined. These experiments were complemented by measurement of the primary and secondary 18-oxygen isotope effects on substrate hydrolysis and a determination of the effects of changing the p K of the leaving group on the magnitude of the rate constants for hydrolysis. Collectively, the results indicated that a single group must be ionized for nucleophilic attack and that a separate general acid is not involved in protonation of the leaving group. The Brønsted analysis and the heavy atom kinetic isotope effects are consistent with an early associative transition state with subsequent proton transfers not being rate limiting. A novel binding mode of the substrate to the binuclear metal center and a catalytic mechanism are proposed to explain the unusual ability of Sb-PTE to hydrolyze unactivated esters from a wide range of organophosphate substrates.
Topics: Bacterial Proteins; Catalysis; Catalytic Domain; Deuterium; Hydrogen-Ion Concentration; Hydrolysis; Kinetics; Magnetic Resonance Spectroscopy; Organophosphates; Paraoxon; Phosphoric Triester Hydrolases; Solvents; Sphingomonadaceae; Viscosity
PubMed: 30730705
DOI: 10.1021/acs.biochem.9b00041 -
Lipids in Health and Disease Apr 2020Recent studies emphasize the importance of HDL function over HDL cholesterol measurement, as an important risk for cardiovascular diseases (CVD). We compared the HDL...
BACKGROUND
Recent studies emphasize the importance of HDL function over HDL cholesterol measurement, as an important risk for cardiovascular diseases (CVD). We compared the HDL function of patients with acute coronary syndrome (ACS) and healthy controls.
METHODS
We measured cholesterol efflux capacity of HDL using THP-1 macrophages labelled with fluorescently tagged (BODIPY) cholesterol. PON1 activities toward paraoxon and phenyl acetate were assessed by spectrophotometric methods.
RESULTS
We recruited 150 ACS patients and 110 controls. The HDL function of all patients during acute phase and at six month follow-up was measured. The mean age of the patients and controls was 51.7 and 43.6 years respectively. The mean HDL cholesterol/apolipoprotein A-I levels (ratio) of patients during acute phase, follow-up and of controls were 40.2 mg/dl/ 112.5 mg/dl (ratio = 0.36), 38.3 mg/dl/ 127.2 mg/dl (ratio = 0.30) and 45.4 mg/dl/ 142.1 mg/dl (ratio = 0.32) respectively. The cholesterol efflux capacity (CEC) of HDL was positively correlated with apolipoprotein A-I levels during acute phase (r = 0.19, p = 0.019), follow-up (r = 0.26, p = 0.007) and of controls (r = 0.3, p = 0.0012) but not with HDL-C levels (acute phase: r = 0.07, p = 0.47; follow-up: r = 0.1, p = 0.2; control: r = 0.02, p = 0.82). Higher levels of cholesterol efflux capacity, PON1 activity and apolipoprotein A-I were associated with lower odds of development of ACS. We also observed that low CEC is associated with higher odds of having ACS if PON1 activity of HDL is also low and vice versa.
CONCLUSION
ACS is associated with reduced HDL functions which improves at follow-up. The predicted probability of ACS depends upon individual HDL functions and the interactions between them.
Topics: Adult; Apolipoprotein A-I; Aryldialkylphosphatase; Case-Control Studies; Cholesterol, HDL; Female; Humans; Lipoproteins, HDL; Male; Middle Aged; ST Elevation Myocardial Infarction
PubMed: 32293456
DOI: 10.1186/s12944-020-01260-4