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1.
The metabolism of a new, selectively toxic derivative of carbofuran, 2,2-dimethyl-2,3-dihydrobenzofuranyl-7 N-methyl-N-(2-toluenesulfenyl)carbamate has been investigated. The selective toxicity between insect and mammal is due to differing pathways of metabolism. Houseflies appear peculiarly suited for the rapid liberation of the toxic agent, carbofuran, from N-(2-toluenesulfenyl) carbofuran in large amounts. Metabolism in the mouse is more complex and involves a series of oxidative and hydrolytic detoxication processes which do not result in the formation of carbofuran.  相似文献   

2.
The metabolism of a selectively toxic derivative of carbofuran, 2,2-dimethyl-2,3-dihydrobenzofuranyl-7 N-dimethoxyphosphinothioyl N-methylcarbamate (PSC), was examined in the house fly, rat, and mouse. In house flies, PSC is metabolized mainly to carbofuran and related oxidation products containing the intact N-methylcarbamyl ester moiety. Degradation to phenolic products was the principal route of metabolism in rodents. The results indicate that the selective toxicity of PSC between insects and mammals is attributable to differing pathways of metabolism.  相似文献   

3.
The metabolism of carbosulfan, 2,3-dihydro-2,2-dimethylbenzofuran-7-yl (di-n-butylaminothio)-methylcarbamate, was studied in the rat and house fly. Carbosulfan was metabolized via at least two major pathways in the rat, by initial oxidation of the sulfur atom and by NS bond cleavage. The principal rat metabolites were the conjugated keto-phenol from the ring-labeled carbo-sulfan, carbon dioxide from the carbonyl-labeled carbosulfan, and dibutylamine from the dibutylamino-labeled carbosulfan. In house flies, carbosulfan was converted primarily into carbofuran and related oxidation products. The lower mammalian toxicity of carbosulfan compared to its insecticidal activity is explained on the basis of differences in routes and rates of metabolism of carbosulfan in mammals and insects.  相似文献   

4.
The fate of the di-n-butylaminosulfenyl moiety in 2,3-dihydro-2,2-dimethyl-7-benzofuranyl (di-n-butylaminosulfenyl)(methyl)carbamate (DBSC or Marshal) was studied in the cotton plant at 1, 3, 6, and 10 days following foliage treatment with [di-n-butylamino-14C]DBSC. Dibutylamine and two major radioactive metabolites were obtained following extraction of the plant tissue with a methanol-buffer containing N-ethylmaleimide (NEM), a sulfhydryl scavenger which was added to prevent the cleavage of the NS bond during the workup procedure. The most adundant radioactive material recovered from plants was identified as a product arising from the reaction between NEM and dibutylamine. Extraction of plant tissue with straight methanol-buffer solution or with methol-buffer containing other sulfhydryl scavengers resulted in 57–86% of the applied radioactivity being recovered as dibutylamine in the organosoluble fraction. When [14C]dibutylamine was applied to cotton leaves, most of the radioactivity, i.e., 96% of the total recovered radioactivity, was found in the organosoluble fraction as dibutylamine. Dibutylamine is the major metabolite of [di-n-butylamino-14C]DBSC in the cotton plant.  相似文献   

5.
Residues of carbofuran ( 1 ) and 2,3-dihydro-3-hydroxy-2,2-dimethylbenzofuran-7-yl methylcarbamate ( 2 ) in and on mushrooms, cultivated on casing soils containing added carbofuran granular insecticide, were determined. The quantitative estimations in cleaned mushroom extracts were done on thin-layer plates using a cholinesterase inhibition method. Samples were analysed, which had been harvested at different times from cultures, to which different amounts of carbofuran were added. Residues in washed and unwashed mushroom samples were compared. Residues did not exceed 0.5 mg (carbofuran) kg?1 and 0.25 mg (compound 2 ) kg?1 for fresh unwashed mushrooms grown on casing soil treated with carbofuran granules 1 g (a.i.) m?2.  相似文献   

6.
The organophosphate insecticides dichlorvos, trichlorphon and isofenphos have been extracted from soil and ryegrass by blending with acetone+ benzene (19+1, v/v) and charcoal. After filtering, water and waxes were precipitated from the extract at ? 78°. The extracts were analysed for insecticide by gas chromatography using alkali flameionisation detection. Trichlorphon was converted to the acetate by on-column acetylation. Recoveries ranged from 73 to 93% for levels of insecticide from 0.1 to 10mg/kg. The carbamate insecticides methomyl and carbofuran plus the metabolite 2,3-dihydro-3-hydroxy-2,2-dimethylbenzofuran-7-yl methylcarbamate have been extracted from soil and ryegrass samples by shaking with acidified ammonium acetate. Following filtration and neutralisation, the aqueous phase was extracted with dichloromethane. The carbamates in the extracts were determined by gas chromatography using on-column trans-esterification to methyl methylcarbamate. Recoveries ranged from 79 to 97% for levels of insecticide from 0.1 to 10 mg/kg.  相似文献   

7.
Major methanol-soluble metabolites of cisanilide (cis-2,5-dimethyl-1-pyrrolidinecarboxanilide) were isolated from excised, pulse-treated carrot and cotton leaves. They were identified as O-glucoside conjugates of primary aryl and alkyl oxidation products, 2,5-dimethyl-1-pyrrolidine-4-hydroxycarboxanilide and 2,5-dimethyl-3-hydroxy-1-pyrrolidinecarboxanilide. Comparative studies with carrot and cotton cell cultures showed similar initial pathways of cisanilide metabolism. Time-course studies with [14C-pyrrolidine]- and [14C-phenyl]cisanilide showed little, if any, cleavage of the herbicide molecule in either excised leaves or cell cultures. Quantitative differences in the metabolism of cisanilide by cell cultures and excised leaves included; a reduced capacity of cell cultures to form secondary glycoside conjugates and an increased ability of cell cultures to form methanol-insoluble residues.  相似文献   

8.
The metabolism of the carbamate insecticide bendiocarb (2,2-dimethylbenzo-1, 3-dioxol-4-yl methylcarbamate) has been investigated in male and female rats and in a male human volunteer using radiolabelled material. The compound was rapidly and extensively absorbed and completely metabolised following oral administration. In man, absorption was complete, >99% of the dose being excreted in the urine within 22 h. In the rat, > 86% of the radiolabel was excreted in the urine within the first 24 h. Faecal excretion from the rat was minor (3–8% of dose) and a small amount of the compound (1–3%) was metabolised and excreted as [14C]carbon dioxide. The major metabolic pathway in both species involved cleavage of the carbamate ester group to yield the phenol,2,2-dimethylbenzo-1, 3-dioxol-4-ol (I). This metabolite, occurring as sulphate and glucuronide conjugates, accounted for more than 95% of the dose excreted by the human volunteer. In man, small amounts of conjugates of 2, 2-dimethylbenzo-1, 3-dioxol-4-yl N-(hydroxymethyl)carbamate (II) were also found in early samples. In the rat, the metabolism was more complex with the formation of small amounts of conjugates of II and several minor metabolites, thought to be ring-hydroxylated derivatives of bendiocarb and I.  相似文献   

9.
The metabolism of the pyrethroid insecticide cypermethrin ([S,R,]-α-cyano-3-phenoxybenzyl-(1R,1S,cis,trans)-2,2-dimethyl-3-(2′,2′-dichlorovinyl)cyclopropane carboxylate), I, has been examined in lettuce plants grown and treated twice under outdoor conditions with 14C-cyclopropyllabeled material. The application rate at each treatment was equivalent to 0.3 kg/ha. At harvest, 21 days after the last application, the plants contained mainly unchanged cypermethrin (33% of the total radiolabel present) and polar materials (54%) which were shown to be conjugates of trans-2(2′,2′-dichlorovinyl)-3,3-dimethylcyclopropane carboxylic acid (II). One of these was identified as the β,d-glucopyranose ester. In separate experiments the uptake and metabolism of the acid (II) in cotton leaves were examined in the laboratory and the acid was shown to be readily converted into a mixture of the β,d-glucopyranose ester, an acidic derivative of this, and disaccharide derivatives including the glucosylarabinose ester and the glycosylxylose ester. Subsequently, cotton leaves were exposed to solutions of these individual conjugates, and interconversions between these metabolites were observed.  相似文献   

10.
Methyl benzimidazol-2-yl carbamate was metabolized by Aspergillus nidulans mycelium to two metabolites, one of which was identified as methyl 5-hydroxybenzimidazol-2-yl carbamate. This compound was further converted to a second metabolite which was not identified. Conversion rate was highest when the culture medium was depleted of nutrients. Especially in aged concentrated mycelial suspensions conversion was rapid and complete. Since strains differing in MBC sensitivity metabolized MBC at equal rates, conversion of MBC to the nonfungitoxic metabolites has no bearing on the mechanism of resistance to this compound.  相似文献   

11.
As part of an extensive study on insect antijuvenile hormones (AJH) structurally related to 2,2-dimethyl-7-methoxychromene and 6,7-dimeth-oxy-2,2-dimethylchromene (precocenes I and II, respectively), four furophenols, six furochromenes, three benzofuran derivatives and two benzochromenes were tested for biological effects on Oncopeltus fasciatus and Locusta migratoria. Exposure to ajar deposit of the chemical was used for O. fasciatus and topical application in acetone for L. migratoria, with precocenes I and II as standards for comparison. All compounds were toxic to O. fasciatus and in some cases, this may have concealed any potential AJH activity, which was not observed for any compound tested. Toxicity to L. migratoria was less evident and three of the furochromene derivatives, allprecocene-I (PI) analogues, showed AJH activity seven to ten-fold lower than that of PI. Neither of the benzochromenes tested showed any AJH activity. The results are discussed in terms of the known structure-activity relationships for precocene-like AJH activity.  相似文献   

12.
Metabolism of [phenyl-14C] and [(2,5) pyrrolidine-14C] cisanilide was investigated in vitro with microsomal preparations from rat liver. Microsomal activity was associated with a mixed-function oxidase system that required O2 and NADPH and was inhibited by CO. Two major ether-soluble metabolites were isolated. They were identified as primary oxidation products: 2-hydroxy-2,5-dimethyl-1-pyrrolidinecarboxanilide (A) and 4′-hydroxy-2,5-dimethyl-1-pyrrolidinecarboxanilide (B). Minor ether-soluble metabolites were also isolated. Precursor product studies and qualitative thin layer chromatography analysis of [pyrrolidine-14C] and methylated [phenyl-14C] hydrolysis products suggested that these metabolites were secondary oxidation products formed from metabolites A or B. One of these metabolites appeared to be the dihydroxy product 2,4′-dihydroxy-2,5-dimethyl-1-pyrrolidinecarboxanilide. Crude microsomal preparations (postmitochondrial supernatant fractions) also formed small quantities (<10%) of polar metabolites. Enzyme hydrolysis with β-glucuronidase (Escherichia coli) indicated that approximately 50% of these metabolites were glucuronides. Similarities and differences in cisanilide oxidation in vivo in plants and in vitro with rat liver microsomal preparations were discussed.  相似文献   

13.
The absorption of the fungicide methyl benzimidazole-2-yl carbamate (M.B.C. or carbendazim) by excised corn (Zea mays L.) roots was studied to determine whether absorption was due to active or passive mechanisms. Carbendazim was probably taken up passively because the temperature coefficient was low, anaerobic conditions or metabolic inhibitors had little effect and the rate of absorption was a linear function of the external concentration.In aqueous solutions, carbendazim can exist at the cationic, anionic or unionized (molecular) forms. Molecular carbendazim was taken up preferentially by corn roots and an accumulation occurred. The efflux of carbendazim from roots was studied and the compartment analysis was utilized.Maximal carbendazim absorption generally occurred in the basal parts of the roots (far from the apex).  相似文献   

14.
The metabolism of R-20458 [(E)-6,7-epoxy-1-(4-ethylphenoxy)-3,7-dimethyl-2-octene] by rat hepatocytes has been analyzed and compared with that of juvenile hormone I [methyl-(E,E)-cis-10,11-epoxy-7-ethyl-3,11-dimethyl-2,6-tridecadienoate] under identical conditions. The metabolism of R-20458 is characterized by the predominance of NADPH-dependent cytochrome P-450 and epoxide hydrolase reactions; whereas, JH I is metabolized mainly by carboxylesterase, epoxide hydrolase, and glutathione S-transferases. The metabolites of R-20458 have been shown to correspond to (E)-6,7-epoxy-1-(4-hydroxyethylphenoxy)-3,7-dimethyl-2-octene; (E)-6,7-epoxy-1-(4-acetylphenoxy)-3,7-dimethyl-2-octene; (E)-6,7-dihydroxy-1-(4-ethylphenoxy)-3,7-dimethyl-2-octene; and, (E)-6,7-dihydroxy-1-(4-acetylphenoxy)-3,7-dimethyl-2-octene. The production of the α-hydroxyethyl, p-acetylphenoxy, and acetylphenoxy-6,7-diol metabolites is markedly inhibited by SKF 525-A. No dramatic effects are produced by diethylmaleate and 1,2-epoxy-3,3,3-trichloropropane.  相似文献   

15.
Clomazone may be safely used in cotton to manage weeds when applied following treatments of the organophosphate insecticides phorate or disulfoton. The loss of chlorophyll and carotenoids with 6 days of 100 nM clomazone treatment of cotton seedlings was partially prevented with phorate in hydroponic solution in a rate-dependent manner. In a study to examine the timing of safening from a one-day clomazone (100 nM) treatment, maximum safening was achieved when phorate (50 μM) was applied the same day as clomazone. Phorate decreased metabolism of 14C-clomazone to polar metabolites in excised cotton shoots and shoots of intact cotton plants. Microsomal studies of corn shoots showed an NADPH-dependent/cytochrome P450 reaction was inhibited by phorate. Additional studies with corn microsomes, corn seedlings and cotton seedlings supported the basis of clomazone safening is the inhibition of toxic clomazone metabolism by P450 inhibitors.  相似文献   

16.
A comparison of different tissues indicated that fat bodies of both the cabbage looper (Trichoplusia ni Hubner) and the European corn borer (Ostrinia nubilalis Hubner) fifth-instar larvae possessed the greatest in vitro metabolic activity towards the anti-juvenile hormone, precocene II (6,7-dimethoxy-2,2-dimethylchromene). Although the metabolic pathway suggested possible involvement of an epoxide hydratase, addition of epoxide hydratase inhibitors to incubation mixtures containing fat body homogenates of either species did not result in an accumulation of intermediate metabolites. However, all of the compounds tested inhibited metabolism of precocene II by mixed-function oxidase(s) as follows: 1,1,1-trichloropropane-2,3-epoxide, 14%; 1,2,3,4-tetradydronapthalene-1,2-epoxide, 63 to 74%; 2,2-bis[4-(2,3-epoxypropyloxy)phenyl] propane, 39 to 63%; cyclohexane oxide, 23 to 63%; and 1-(4-propargylphenoxy)-2,3-epoxypropane, 85 to 92%.  相似文献   

17.
The cotton bollworm, Helicoverpa armigera is a polyphagous pest of several crops in Asia, Africa, and the Mediterranean Europe. Organophosphate and carbamate insecticides are used on a large-scale to control Helicoverpa. Therefore, we studied the effect of methylparathion and carbofuran, an organophosphate and carbamate insecticide, respectively, on oxidative phosphorylation and oxidative stress in H. armigera larvae to gain an understanding of the different target sites of these insecticides. It was observed that state III and state IV respiration, respiratory control index (RCI), and P/O ratios were inhibited in a dose-dependent manner by methylparathion and carbofuran under in vitro and in vivo conditions. Methylparathion and carbofuran inhibited complex II by ∼45% and 30%, respectively. Lipid peroxidation, H2O2 content, and lactate dehydrogenase (LDH) activity increased and glutathione reductase (GR) activity decreased in a time- and dose-dependent manner in insecticide-fed larvae. However, catalase activity was not affected in insecticide-fed larvae. Larval growth decreased by ∼64% and 67% in larvae fed on diets with 100 μM of methylparathion and carbofuran. The results suggested that both the insecticides impede the mitochondrial respiratory functions and induced lipid peroxidation, H2O2, and LDH leak, leading to oxidative stress in cells, which contribute to deleterious effects of these insecticides on the growth of H. armigera larvae, along with their neurotoxic effects.  相似文献   

18.
The movement of the organophosphate nematicide-insecticide ethoprophos (ethoprop; O-ethyl S,S-dipropyl phosphorodithioate) and the carbamate insecticide-nematicide carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yI methylcarbamate) was studied under steady-state flow in small-scale laboratory soil columns. Miscible displacement column experiments, mass balance calculations, and batch incubation studies furnished information on insecticide sorption and degradation processes that occur during transport through soil. Miscible displacement studies demonstrated that ethoprophos degradation could be described as first-order and that both insecticides exhibited non-equilibrium sorption. Both batch and miscible displacement results showed ethoprophos to be more strongly sorbed by soil than carbofuran. Measured equilibrium sorption coefficients were 1.29 cm3 g?1 for ethoprophos and 0.29 cm3 g?1 for carbofuran on a Riverhead soil (0.011 organic carbon fraction); 035 cm3 g?1 for carbofuran on Valois soil (0.016 organic carbon fraction); and 2.38 cm3 g?1 for ethoprophos on Rhinebeck soil (0.031 organic carbon fraction). Two solutions to the convection-dispersion equation, one that incorporated equilibrium sorption and another (bicontinuum model) that included a non-equilibrium sorption term, allowed quantitative evaluation of transport processes. The bicontinuum model used in conjunction with experimental batch and mass balance techniques provided estimates of insecticide sorption and degradation parameters.  相似文献   

19.
The uptake and translocation of 14C-labelled ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethylbenzofuran-5-yl methanesulphonate] was studied in sugar-beet seedlings following soil and foliar applications. After soil applications, the roots absorbed and translocated to the foliage more ethofumesate or its metabolites than did the emerging hypocotyls. Ethofumesate or its metabolites did not accumulate in either roots or hypocotyls after exposure to treated soil. When sugar-beet leaves were treated with the herbicide at the two-leaf stage, acropetal translocation was rapid but there was no translocation out of the treated leaves. Furthermore, ethofumesate or its metabolites were not translocated basipetally after either soil or foliar application.  相似文献   

20.
Fourteen oxime ethers and eleven other unsaturated compounds derived from 2,2-dimethyl-3-(3-phenoxybenzyloxy)propanal were synthesised and their insecticidal activity against Musca domestica, Locusta migratoria, Dysdercus cingulatus, Aedes aegypti, Plutella xylostella, Drosophila melanogaster, Tetranychus urticae and Spodoptera littoralis tested. Structural variations including chain length, branching and unsaturation of the oxime ether O-alkyl group and substituent exchange at the carbon-carbon double bond of the unsaturated compounds were made in order to examine the structure-activity relationship. All biological activities were compared with the activity of the ether pyrethroid MTI-500.  相似文献   

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