The pyrethroids: Early discovery, recent advances and the future

Elliott, M.

doi:10.1002/ps.2780270403

Cited by 85 publications

(42 citation statements)

References 21 publications

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“…Deltamethrin was discovered by replacing a bromine for a chlorine atom in the acid side chain, making it possible to isolate a single crystalline product ([1R, cis] a-S isomer) with all three centers resolved (Elliott et al 1974). Permethrin, cypermethrin, and deltamethrin were introduced by Elliott et al (1974, , Elliott (1989), and Fisher et al (1983). Phenothrin contains four optical and stereo isomers, with only the [1R, trans] and [1R, cis] isomers being insecticidally active.…”

Section: Discoverymentioning

confidence: 98%

Parameters for Pyrethroid Insecticide QSAR and PBPK/PD Models for Human Risk Assessment

Knaak

Dary²,

Zhang

et al. 2012

Reviews of Environmental Contamination and Toxicology

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In this review we have examined the status of parameters required by pyrethroid QSAR-PBPK/PD models for assessing health risks. In lieu of the chemical,biological, biochemical, and toxicological information developed on the pyrethroids since 1968, the finding of suitable parameters for QSAR and PBPK/PD model development was a monumental task. The most useful information obtained came from rat toxicokinetic studies (i.e., absorption, distribution, and excretion), metabolism studies with 14C-cyclopropane- and alcohol-labeled pyrethroids, the use of known chiral isomers in the metabolism studies and their relation to commercial products. In this review we identify the individual chiralisomers that have been used in published studies and the chiral HPLC columns available for separating them. Chiral HPLC columns are necessary for isomer identification and for developing kinetic values (Vm,, and Kin) for pyrethroid hydroxylation. Early investigators synthesized analytical standards for key pyrethroid metabolites, and these were used to confirm the identity of urinary etabolites, by using TLC. These analytical standards no longer exist, and muste resynthesized if further studies on the kinetics of the metabolism of pyrethroids are to be undertaken.In an attempt to circumvent the availability of analytical standards, several CYP450 studies were carried out using the substrate depletion method. This approach does not provide information on the products formed downstream, and may be of limited use in developing human environmental exposure PBPK/PD models that require extensive urinary metabolite data. Hydrolytic standards (i.e., alcohols and acids) were available to investigators who studied the carboxylesterase-catalyzed hydrolysis of several pyrethroid insecticides. The data generated in these studies are suitable for use in developing human exposure PBPK/PD models.Tissue:blood partition coefficients were developed for the parent pyrethroids and their metabolites, by using a published mechanistic model introduced by Poulin and Thiele (2002a; b) and log DpH 7.4 values. The estimated coefficients, especially those of adipose tissue, were too high and had to be corrected by using a procedure in which the proportion of parent or metabolite residues that are unbound to plasma albumin is considered, as described in the GastroPlus model (Simulations Plus, Inc.,Lancaster, CA). The literature suggested that Km values be adjusted by multiplying Km by the substrate (decimal amount) that is unbound to microsomal or CYPprotein. Mirfazaelian et al. (2006) used flow- and diffusion-limited compartments in their deltamethrin model. The addition of permeability areas (PA) having diffusion limits, such as the fat and slowly perfused compartments, enabled the investigators to bring model predictions in line with in vivo data.There appears to be large differences in the manner and rate of absorption of the pyrethroids from the gastrointestinal tract, implying that GI advanced compartmental transit models (ACAT) need to be included in PBPK mo...

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Section: Discoverymentioning

confidence: 98%

Parameters for Pyrethroid Insecticide QSAR and PBPK/PD Models for Human Risk Assessment

Knaak

Dary²,

Zhang

et al. 2012

Reviews of Environmental Contamination and Toxicology

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“…Compared with the pyrethrins, the pyrethroids display enhanced insecticidal activity, greater environmental stability, greater resistance to metabolism, and increased mammalian toxicity (Elliot, 1989;Soderlund, 1992). There is no evidence that metabolites of the pyrethrins or pyrethroids induce neurobehavioral changes or other toxic effects.…”

mentioning

confidence: 99%

Identification of Rat and Human Cytochrome P450 Isoforms and a Rat Serum Esterase That Metabolize the Pyrethroid Insecticides Deltamethrin and Esfenvalerate

Godin

Crow²,

Scollon³

et al. 2007

Drug Metab Dispos

123

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ABSTRACT:The metabolism of (␣S)-cyano-3-phenoxybenzyl (1R, 3R)-cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylate (deltamethrin) and (␣S)-cyano-3-phenoxybenzyl 2-(4-chlorophenyl)-3-methylbutyrate (esfenvalerate) by rat and human liver microsomes differs with respect to the biotransformation pathway (oxidation versus hydrolysis) responsible for their clearance. This study aims to further explore the species differences in the metabolism of these chemicals. Using a parent depletion approach, rat and human cytochromes P450 (P450s) were screened for their ability to eliminate deltamethrin or esfenvalerate during in vitro incubations. Rat P450 isoforms CYP1A1, CYP2C6, CYP2C11, and CYP3A2 and human P450 isoforms CYP2C8, CYP2C19, and CYP3A5 were capable of metabolizing either pyrethroid. Human CYP2C9 metabolized esfenvalerate but not deltamethrin. Rat and human P450s that metabolize esfenvalerate and deltamethrin do so with similar kinetics. In addition to the liver, a potential site of metabolic elimination of pyrethroids is the blood via serum carboxylesterase (CE) hydrolysis. The serum of rats, but not humans, contains significant quantities of CE. Deltamethrin and esfenvalerate were metabolized effectively by rat serum and a purified rat serum CE. In contrast, neither pyrethroid was metabolized by human serum or purified human serum esterases (acetylcholinesterase and butyrylcholinesterase). These studies suggest that the difference in rates of oxidative metabolism of pyrethroids by rat and human hepatic microsomes is dependent on the expression levels of individual P450 isoforms rather than their specific activity. Furthermore, these studies show that the metabolic elimination of deltamethrin and esfenvalerate in blood may be important to their disposition in rats but not in humans.

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“…This property causes strong sorption to soil organic matter, and limited its leaching into groundwater (Oudou and Hansen 2002). In soil, deltamethrin undergoes various dissipation processes and is degraded via hydrolysis, photolysis, and microbial activity with halflife ranged from 11 to 72 days, depending on the soil type and oxygen availability (Elliott 1989;WHO 1990). Degradation of deltamethrin is slower under anaerobic or sterile conditions, indicating important role of soil microorganisms in this process (Chapman et al 1981;Zhang et al 1984;Grant and Betts 2004).…”

Section: Introductionmentioning

confidence: 99%

Enhancement of deltamethrin degradation by soil bioaugmentation with two different strains of Serratia marcescens

Cycoń

Żmijowska

Piotrowska‐Seget

2013

Int. J. Environ. Sci. Technol.

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Deltamethrin is one of the most commonly used pyrethroid in agricultural practice in different geographic regions of the world. It is detected in many environments, especially in soil and water, and can exhibit toxic effect to human and other organisms. In this study, we describe two bacterial strains DeI-1 and DeI-2, isolated from soil, and both identified as Serratia marcescens based on profile of the fatty acid methyl esters, biochemical test, and 16S RNA gene analysis, which were shown to efficiently degrade deltamethrin. Degradation of deltamethrin in mineral salt medium (50 mg l -1 ) proceeded by strains DeI-1 or DeI-2 reached the values of 88.3 or 82.8 % after 10 days, and DT50 was 2.8 or 4.0 days, respectively. Bioaugmentation of deltamethrin-contaminated non-sterile soils (100 mg kg -1 ) with strains DeI-1 or DeI-2 (3 9 10 6 cells g -1 of soil) enhanced the disappearance rate of pyrethroid, and its DT50 was reduced by 44.9, 33.1, 44.4, and 58.2 days or 39.1, 25.8, 35.6, and 46.0 days in sandy, sandy loam, silty loam, and silty soils, respectively, in comparison with non-sterile soils with only indigenous microflora. The three-way ANOVA indicated that DT50 of deltamethrin was significantly (P \ 0.01) affected by soil type, microflora presence, and inoculum, and the interaction between these factors. Generally, the lower content of clay and organic carbon in soil, the higher degradation rate of deltamethrin was observed. Obtained results show that both strains of S. marcescens may possess potential to be used in bioremediation of deltamethrincontaminated soils.

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The pyrethroids: Early discovery, recent advances and the future

Cited by 85 publications

References 21 publications

Parameters for Pyrethroid Insecticide QSAR and PBPK/PD Models for Human Risk Assessment

Parameters for Pyrethroid Insecticide QSAR and PBPK/PD Models for Human Risk Assessment

Identification of Rat and Human Cytochrome P450 Isoforms and a Rat Serum Esterase That Metabolize the Pyrethroid Insecticides Deltamethrin and Esfenvalerate

Enhancement of deltamethrin degradation by soil bioaugmentation with two different strains of Serratia marcescens

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