Characterization of the Transient Oxaphosphetane BChE Inhibitor Formed from Spontaneously Activated Ethephon

Lantz, Stephen R.; Casida, John E.

doi:10.1021/tx4002429

Cited by 3 publications

(4 citation statements)

References 13 publications

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“…2,3 Phosphonic acid can accumulate and be stored for years and remobilized by the plant, suggesting a long-term persistence and nonpredictable residual effects in fruits and vegetables. 3,4 In case of a treatment with the phosphonate fungicide fosetyl aluminum, phosphonic acid is the main metabolite. 5 The application of fosetyl aluminum is allowed for a quite large number of commodities.…”

Section: ■ Introductionmentioning

confidence: 99%

Determination of Fosetyl and Phosphonic Acid at 0.010 mg/kg Level by Ion Chromatography Tandem Mass Spectrometry

Bauer

Luetjohann

Rohn

et al. 2017

J. Agric. Food Chem.

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A new sensitive, fast, and robust method using ion chromatography tandem mass spectrometry (IC-MS/MS) for the determination of fosetyl and phosphonic acid in plant-derived matrices was developed. For compensation of matrix effects and differences in recovery rates the isotopically labeled internal standard (ILIS) O-labeled phosphonic acid was added to the samples prior to the extraction of the target compounds. The validation of the method for the matrices tomato, apple, lemon, sultana, avocado, and wheat was performed according to the actual EU guidance document SANTE/11945/2015. The precision and accuracy were determined in five replicates at spiking levels of 0.010 and 0.100 mg/kg with recovery rates between 76 and 105% and RSDs between 1.2 and 17.8%. In this paper, it was achieved for the first time to detect both fosetyl and phosphonic acid at the reporting level of 0.010 mg/kg most relevant for organic plant food commodities.

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Section: ■ Introductionmentioning

confidence: 99%

Determination of Fosetyl and Phosphonic Acid at 0.010 mg/kg Level by Ion Chromatography Tandem Mass Spectrometry

Bauer

Luetjohann

Rohn

et al. 2017

J. Agric. Food Chem.

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“…The toxicity of glufosinate to mammals may involve the N-methyl-D-aspartate receptor (84,85). Ethephon (Figure 2, OP 11) is an important OP plant growth regulator acting as an ethylene generator but with the intriguing side reaction of inhibiting BChE by a spontaneously formed cyclic oxaphosphetane (Figure 2, proposed structure OP 11) (86,87). Ethylene acts as a plant growth regulator in signal translation, a property that does not pose a hazard for mammals.…”

Section: Herbicidesmentioning

confidence: 99%

Organophosphorus Xenobiotic Toxicology

Casida

2017

Annu. Rev. Pharmacol. Toxicol.

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Originally, organophosphorus (OP) toxicology consisted of acetylcholinesterase inhibition by insecticides and chemical threat agents acting as phosphorylating agents for serine in the catalytic triad, but this is no longer the case. Other serine hydrolases can be secondary OP targets, depending on the OP structure, and include neuropathy target esterase, lipases, and endocannabinoid hydrolases. The major OP herbicides are glyphosate and glufosinate, which act in plants but not animals to block aromatic amino acid and glutamine biosynthesis, respectively, with safety for crops conferred by their expression of herbicide-tolerant targets and detoxifying enzymes from bacteria. OP fungicides, pharmaceuticals including calcium retention agents, industrial chemicals, and cytochrome P450 inhibitors act by multiple noncholinergic mechanisms, often with high potency and specificity. One type of OP-containing fire retardant forms a highly toxic bicyclophosphate γ-aminobutyric acid receptor antagonist upon combustion. Some OPs are teratogenic, mutagenic, or carcinogenic by known mechanisms that can be avoided as researchers expand knowledge of OP chemistry and toxicology for future developments in bioregulation.

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“…20 The plant growth regulator ethephon, 4C, at physiological pH undergoes spontaneous activation not only to ethylene but also to a butyrylcholinesterase inhibitor tentatively proposed to be a cyclic oxaphosphetane. 21,22 ■ CYP INHIBITORS AS SYNERGISTS CYP inhibitors increase the toxicity of many insecticides 23−25 by intention (synergists shown in Figure 5) or inadvertent exposure (fungicidal ergosterol biosynthesis inhibitors). The most important insecticide synergist is piperonyl butoxide, 5A, with the methylenedioxy carbon as the critical site of CYP interaction.…”

Section: ■ Procyclic Phosphatesmentioning

confidence: 99%

“…OC 6 H 4 -4-NO 2 or SC 2 H 5 ), is activated by CYP-mediated or in vivo cyclization . The plant growth regulator ethephon, 4C , at physiological pH undergoes spontaneous activation not only to ethylene but also to a butyrylcholinesterase inhibitor tentatively proposed to be a cyclic oxaphosphetane. , …”

Section: Procyclic Phosphatesmentioning

confidence: 99%

Unexpected Metabolic Reactions and Secondary Targets of Pesticide Action

Casida

2016

J. Agric. Food Chem.

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Pesticides provide a fascinating combination of substituents not present in other environmental chemicals, leading to unexpected metabolites and toxicological effects in pests, mammals, and other organisms. The parent compound and/or metabolites of some pesticides have multiple targets, requiring identification of the causal agents and their modes of action. This review considers a few of the author's observations in the past six decades, some solved and others still puzzling. It illustrates that a new substituent combination not only confers specific chemical and physical properties to a class of compounds but often yields metabolites with a surprising variety of biological activities. Examples considered include proinsecticides, procyclic phosphates, CYP inhibitors as synergists, thiocarbamate sulfoxides, promutagens, carcinogens, and hepatotoxins, and stress tolerance inducers in plants. Although the discoveries considered are based on pesticide toxicology, they are broadly applicable to environmental toxicology and xenobiotics in animals, plants, and microorganisms.

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Characterization of the Transient Oxaphosphetane BChE Inhibitor Formed from Spontaneously Activated Ethephon

Cited by 3 publications

References 13 publications

Determination of Fosetyl and Phosphonic Acid at 0.010 mg/kg Level by Ion Chromatography Tandem Mass Spectrometry

Determination of Fosetyl and Phosphonic Acid at 0.010 mg/kg Level by Ion Chromatography Tandem Mass Spectrometry

Organophosphorus Xenobiotic Toxicology

Unexpected Metabolic Reactions and Secondary Targets of Pesticide Action

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