Metabolism of four resmethrin isomers by liver microsomes

Ueda, Kenzo; Gaughan, Loretta C.; Casida, John E.

doi:10.1016/0048-3575(75)90010-3

Cited by 55 publications

(40 citation statements)

References 9 publications

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“…Malathion also inhibits hydrolysis of fenothrin and vice versa, and the identity of pyrethroid esterases with malathion carboxylesterase is suspected (27). What is interesting here is that none of the cis isomers tested, whether it be the (+) -or (-)-enantiomer, is a good substrate for the esterases, and they are hydrolyzed at a far slower rate, as shown in Figure 1 (18,(24)(25)(26)) (also Table 3). As is evident from the results, (+ )-cis-resmethrin is hydrolyzed at a rate one-tenth of that of (+ )-trans resmethrin by mouse hepatic esterases.…”

Section: Metabolism In Mammalsmentioning

confidence: 99%

“…Not only fenothrin shown here, but all (+ )-and (-)-trans isomers of resmethrin, tetramethrin, and permethrin are well hydrolyzed by the enzymes (25)(26)(27). Organophosphorus compounds such as S,S,S-tributyl phosphorothiolate, paraoxon, malaoxon and NIA16388 as well as insecticidal carbamates -inhibit the hydrolysis reaction (23,25,26,28). Malathion also inhibits hydrolysis of fenothrin and vice versa, and the identity of pyrethroid esterases with malathion carboxylesterase is suspected (27).…”

Section: Metabolism In Mammalsmentioning

confidence: 99%

“…More or less similar relationships hold true for the isomers of fenothrin, permethrin, and tetramethrin. In vitro, the cis isomers of these pyrethroids are degraded oxidatively by NADPH-fortified mfo (23,26).…”

Section: Metabolism In Mammalsmentioning

confidence: 99%

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Degradation, metabolism and toxicity of synthetic pyrethroids.

Miyamoto¹

1976

Environ Health Perspect

202

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Synthetic pyrethroidal compounds undergo biodegradation in mammals both oxidatively and hydrolytically, and depending on the type of compound, either of the pathways may predominate. Thus, (+) -or (±) -trans isomers of the chrysanthemumate ester of primary alcohols such as fenothrin, furamethrin, proparthrin, resmethrin, and tetramethrin (and possibly permethrin, too) are metabolized mainly through hydrolysis of the ester linkage, with subsequent oxidation and/or conjugation of the component alcohol and acid moieties. On the other hand, the corresponding (+ )-cis enantiometers and chrysanthemumate of secondary alcohols like allethrin are resistant to hydrolytic attack, and biodegraded via oxidation at various sites of the molecule. These rapid metabolic degradations, together with the presumable incomplete absorption from the gastrointestinal tract, would generally contribute to the low acute toxicity of synthetic pyrethroids.These compounds are neither skin irritants nor skin sensitizers, and inhalation toxicity as well as dermal toxicity are fairly low. Neither is teratogenic in rats, mice, and/or rabbits or mutagenic on various bacterial strains. Subacute and chronic feeding of higher amounts of the compounds to rats invariably causes some histopathological changes in liver; however, these are neither indicative nor suggestive of tumorigenicity.Based on existing toxicological information, the present recommended use patterns might afford sufficient safety margin on human population.However, in extending usage to agricultural pest control, much more extensive investigations should be forthcoming from both chemical and biological aspects, since there is scant information on the fate of these pyrethroids in the environment. Also several of the compounds may be very toxic to certain kinds of fish and arthropods.

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Section: Metabolism In Mammalsmentioning

confidence: 99%

Section: Metabolism In Mammalsmentioning

confidence: 99%

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Degradation, metabolism and toxicity of synthetic pyrethroids.

Miyamoto¹

1976

Environ Health Perspect

202

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“…Since varying stereoisomers of both OPs and pyrethroids exhibit differential toxic effects, 50,[56][57][58][59] stereospecific hydrolysis is essential in the determination of their toxic properties. In studies on the metabolism of pyrethroids such as allethrin, 50) resmethrin, 60,61) phenothrin, 62) permethrin, 63,64) and cypermethrin, 64) it has been demonstrated that the trans-isomers are more rapidly hydrolyzed than the corresponding cis-isomers in both mammals and insects. These findings support the generally observed lower toxicity of trans-isomers.…”

Section: Agrochemical Metabolism and Role In Insecticide Resistancementioning

confidence: 99%

Overview of Carboxylesterases and Their Role in the Metabolism of Insecticides

Shan²,

2005

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Carboxylesterases hydrolyze numerous endogenous and exogenous ester-containing compounds. They play a role in the detoxification of many agrochemicals including pyrethroids, organophosphates, and carbamates. Research on these enzymes is still developing and there are several topics that should be addressed to further investigations in this area. This paper focuses on a number of these issues including enzyme nomenclature, catalytic mechanism, substrate specificity, agrochemical metabolism, role in insecticide resistance and environmental significance. It is expected that carboxylesterase research will increase with specific emphasis on isozyme and substrate identification. Future research directions are discussed and the current state of the field is evaluated.

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“…The less desirable properties of chlorinated hydrocarbon insecticides are associated with their lipophilicity and inert chemical structures so that they are stored in the fatty tissues of organisms rather than being metabolized and eliminated. Although pyrethroids are similar to the chlorinated hydrocarbons in some of their physical properties, much evidence from research in the past decade (59)(60)(61)(62)(63)(64)(65)(66)(67)(68) suggests that the structural features of pyrethroids render them susceptible to mammalian detoxification systems, so that by one or more of several possible pathways they are rapidly converted to more polar compounds and are excreted in the urine or feces.…”

Section: Physical Properties Of Pyrethroids and Other Insecticidesmentioning

confidence: 99%

Properties and applications of pyrethroids.

Elliott¹

1976

Environ Health Perspect

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Improved understanding of the factors determining the insecticidal activity, the mammalian toxicity, and the stability in air and light of natural and synthetic pyrethroids has led to a series of new compounds with a very favorable combination of properties. Their characteristicsinclude outstanding potency to insects, low toxicity to mammals associated with rapid metabolic breakdown and, in appropriate cases, adequate stability on plant surfaces even in bright sunlight. Initial tests indicate that even the more stable compounds are degraded rapidly in soil, so if the trials at present in progress reveal no toxicological or environmental hazards, within a few years synthetic pyrethroids should be available to control a wide range of domestic, veterinary, horticultural, agricultural, and forest pests at low rates of application.

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Metabolism of four resmethrin isomers by liver microsomes

Cited by 55 publications

References 9 publications

Degradation, metabolism and toxicity of synthetic pyrethroids.

Degradation, metabolism and toxicity of synthetic pyrethroids.

Overview of Carboxylesterases and Their Role in the Metabolism of Insecticides

Properties and applications of pyrethroids.

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