共查询到20条相似文献，搜索用时 296 毫秒
1.
Inhibition of S-cysteinyl-hydroxychlorpropham transferase from oat (Avena sativa L.) by various compounds was studied. The β-O-glucoside of the substrate, isopropyl-3′-chloro-4′-hydroxycarbanilate (4-hydroxychlorpropham), and isopropyl-3′-chlorocarbanilate (chlorpropham) did not inhibit the enzyme. Isopropyl-5′-chloro-2′-hydroxycarbanilate (2-hydroxy-5-chlorpropham), was a competitive inhibitor with respect to 4-hydroxychlorpropham, but 2-β-O-glucosyl-5-chlorpropham was not an inhibitor. The inhibition patterns exhibited by 2-hydroxy-5-chlorpropham and other aryl-hydroxylated analogs suggested that the site of aryl-cysteine thioether conjugation might be the ortho (2′) aromatic carbon. Inhibitions by 3-chloro-4-hydroxyaniline and ferulic acid suggest that related phenols and/or naturally occurring phenolic plant acids could serve as substrates for the enzyme system. Glutathione was a competitive inhibitor with respect to cysteine and could also form a conjugate with 4-hydroxychlorpropham. Atypical inhibitions of cysteine conjugation by cysteine ethyl ester or firefly d-luciferin were described. Similarities between S-cysteinyl-hydroxychlorpropham transferase and firefly luciferase were noted. 相似文献
2.
Isopropyl-3′-chlorocarbanilate (chlorpropham) forms phenolic metabolites, isopropyl-3′-chloro-4′-hydroxycarbanilate (I), and isopropyl-5′-chloro-2′-hydroxycarbanilate (II), in several plant species. In oat, which is a chlorpropham-susceptible plant, I was converted to an S-cysteinyl-conjugate (III). The reaction in vitro was catalyzed by a partially purified, soluble enzyme. The formation of III by the enzyme preparation and by oat shoot sections was compared. Mass spectral data indicated the presence of an aryl-thioether bond, and chloro-, hydroxy-, and isopropylcarbanilate groups in III. The results of this investigation indicate that III was isopropyl-[(2-amino-2-carboxyethyl)thio]-chloro-hydroxycarbanilate (S-cysteinyl-hydroxychlorpropham). 相似文献
3.
S-Cysteinyl and glutathione conjugates of isopropyl-3′-chloro-4′-hydroxycarbanilate (4-hydroxychlorpropham) were synthesized directly in the presence of soluble enzyme systems isolated from etiolated shoots of oat seedlings. The enzyme systems responsible for these reactions were partially purified and charaterized. Enzyme A appeared to be a multicomponent system, equally reactive with either cysteine or glutathione. Enzyme B was twice as active as enzyme A in the formation of S-cysteinyl-hydroxychlorpropham. Affinity chromatography of enzyme A produced an enzyme fraction with properties similar to those of enzyme B. Both enzymes (A and B) were significantly inhibited by increased cysteine concentrations. The reaction of glutathione with enzyme B was limited. However, when low concentrations of a nonreacting effector, cysteine ethyl ether, were added, glutathione conjugation increased significantly. At higher concentrations, cysteine ethyl ester formed a conjugate with 4-hydroxychlorpropham. Isopropyl-5′-chloro-2′-hydroxycarbanilate (2-hydroxy-5-chlorpropham) did not conjugate with either cysteine or glutathione but did react with cysteine ethyl ester. Isopropyl-3′-chlorocarbanilate (chlorpropham) was not a substrate for thioether conjugation. These data suggest that para- and/or ortho-hydroxylated carbanilates and cysteine-related substrates may form thioether conjugates when incubated under appropriate conditions with these complex enzyme systems. 相似文献
4.
Diphenyl ethers exhibit different modes of action according to their chemical constitution. Diphenyl ethers of the m-phenoxybenzamide type, which were found to be effective on carotenogenesis resulting in an accumulation of colorless carotenoid precursors, mostly phytoene, indicative of inhibition of desaturation, are discussed. As seen with other carotenoid biosynthesis inhibitors, a concurrent loss of chlorophyll was observed as a secondary effect caused by the absence of protective carotenoids. In contrast to peroxidative p-nitrodiphenyl ethers like oxyfluorfen (2-chloro-4-trifluoromethylphenyl-3′-ethoxy-4′-nitrophenyl ether), the m-phenoxybenzamides assayed showed the same phytotoxic mode of action in the dark as observed when using heterotrophic Scenedesmus cultures. As expected, chlorophylls were not affected. The decrease of carotenoids was not due to their degradation but to inhibited carotenogenesis. Examination of carotenoid fractions show that the m-phenoxybenzamides, e.g., 3-(2,5-dimethylphenoxy)-N-ethylbenzamide, used here act similarly to 2-phenylpyridazinones like norflurazon [4-chloro-5-methylamino-2-(2-trifluoromethylphenyl)-pyridazin-3(2H)one]. All these inhibitors strongly decrease the α- and β-carotene content, while xanthophyll content is not lowered as much. 相似文献
5.
In the Japanese quail, cytochrome P-450, A- and B-esterase, amidase, and glutathione S-aryl transferase were assayed in postmitochondrial centrifugal fractions, in microsomes, and supernatant fractions of liver, lungs, kidneys, and testes. Liver microsomes contained the highest A-esterase activity and P-450 levels. B-esterase was more generally distributed and higher in the microsomal tissue fractions. Microsomal amidase activity was highest in quail lung and kidney, and lowest in the liver (per mg protein). Very little difference in glutathione S-aryl transferase activity was noted among the tissues assayed. In vitro metabolism of carbaryl, phosphamidon, and chlorotoluron by the various centrifugal fractions revealed that the production of 1-naphthyl-N-hydroxymethylcarbamate and 1-naphthol, the major metabolites, was greatest in the postmitochondrial fraction of the liver. The major carbaryl metabolite in all other quail tissue fractions was 1-naphthol. Phosphamidon metabolism in postmitochondrial preparations of quail liver was higher than in the supernatant and microsomes. Chlorotoluron metabolism occurred only in the postmitochondrial fractions of quail liver. The major products were the oxidative metabolites, N-(3-chloro-4-methylphenyl)-N′-methylurea and N-(3-chloro-4-hydroxymethylphenyl)-N′-methylurea. 相似文献
6.
N.D. Camper Merrill Wilcox K.L. Ellers J.E. Doeller 《Pesticide biochemistry and physiology》1982,18(2):247-252
The activity of two groups of growth regulators, substituted dinitroanilines and nitrophenylhydrazines, were evaluated in a tobacco (Nicotiana tabacum L. “X-73”) callus tissue bioassay. Molar concentrations required to inhibit fresh weight gain by 50% (I50) was determined by using linear regression analysis on data obtained by testing a range of five concentrations of each chemical. All chemicals tested were inhibitory to callus tissue grown in the dark. Cell division seemed to be the primary activity inhibited. The most active of the dinitroaniline series was α,α,α-trifluoro-2,6-dinitro-N-ethyl-N-2′,6′-dichlorobenzyl-p-toluidine (I) (I50 = 1.5 × 10?10M). I and two other N-(o-halobenzyl) dinitroanilines were more active than α,α,α-trifluoro-2,6-dinitro-N-ethyl-N-2′-chloro-6′-fluorobenzyl-p-toluidine (IV), which is being developed commercially for suppression of axillary buds in tobacco. The two most active nitrophenylhydrazines tested were 1,1-dimethyl-2-(2′,6′-dinitro-3′-n-propylamino-α,α,α-trifluoro-p-tolyl)hydrazine (XVIII) and 3′,5′-dinitro-p-(2,2-diethylhydrazino)-N-methoxy-N-methylbenzamide (XIX) (I50 values of 7.9 × 10?9 and 9.3 × 10?9M, respectively). Factors such as electronic distribution, steric hindrance, and lipid solubility were considered to influence the biological activity of the compounds tested. 相似文献
7.
The inhibition site of the phenylpyridazinone herbicide, norflurazon [SAN 9789, 4-chloro-5-(methylamino)-2-(3-trifluoromethylphenyl)-pyridazin-3(2H)one] was determined in a cell-free carotenogenic enzyme system from a mutant strain of Phycomyces blakesleeanus (Mucoraceae). The presence of norflurazon resulted in a reduced flow of radioactivity from [2-14C]mevalonic acid to phytoene (7,8,11,12,7′,8′,11′,12′-octahydro-ψ,ψ-carotene) and β-carotene (β,β-carotene), whereas an increased incorporation occurred in the C30 terpenoids, squalene, and ergosterol. Furthermore, radioactivity accumulated in geranylgeranyl pyrophosphate. Since no radioactivity was found in prephytoene pyrophosphate and the radioactivity in phytoene decreased upon addition of norflurazon, this herbicide exerts its primary inhibitory action on the reaction catalyzed by phytoene synthetase. The nonbleaching phenylpyridazinone BAS 13761 [4-chloro-5-methoxy-2-phenyl-pyridazin-3(2H)-one] did not show this effect. Other inhibitory sites of norflurazon, either on prenyl pyrophosphate synthetase or on the desaturation of phytoene, were excluded. 相似文献
8.
Chlorella pyrenoidosa, Chlorococcum sp., Lyngbya sp., and Anabaena variabilis were cultured in Bold's basal medium. They were treated with 0.1, 1.0, and 10 μM concentrations of 2-chloro-2′, 6′-diethyl-N-(methoxymethyl)acetanilide (alachlor), 2-chloro-4-(ethylamino)-6-(tert-butyl-amino)-s-triazine (terbuthylazine), 2-sec-butyl-4,6-dinitrophenol (dinoseb), 1,1-dimethyl-3-(α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine) (profluralin), 2, 4-bis(isopropylamino)-6-(methylthio)-s-triazine (prometryne), and (2,4-dichlorophenoxy)acetic acid (2,4-D). Growth of all algal species tested was markedly reduced by the triazines. Alachlor, dinoseb, and fluometuron inhibited growth of some algae at higher concentrations while 2,4-D and profluralin did not inhibit growth at the concentrations tested. Photosynthesis was greatly inhibited by the triazines, even at the 0.1 μM concentration. Fluometuron was very toxic to the blue-green algae but had less effect on the green algae tested. Lyngbya was most susceptible to photosynthesis reduction by the herbicides. The concentrations of herbicides tested had little effect on respiration of the algae species. It appears that effects on algal growth were due primarily to inhibition of photosynthesis rather than to other metabolic processes. 相似文献
9.
Terry R. Roberts 《Pest management science》1977,8(5):463-472
The metabolism of the wild oat herbicide flamprop-methyl, methyl (±)-2-[N-(3-chloro-4-fluorophenyl)benzamido]propionate, in spring wheat grown to maturity has been studied under glasshouse and outdoor conditions. [14C]-Flamprop-methyl labelled separately in the halophenyl ring and the carbonyl of the benzoyl group was used. The major metabolite formed in plants was the corresponding carboxylic acid, II, which also occurred as conjugates. Other minor metabolites detected under glasshouse conditions only were the 3- and 4-hydroxybenzoyl analogues of flamprop-methyl and 3′-chloro-4′-fluorobenzanilide. The soil in which the plants were grown contained residues comprising mainly flamprop-methyl and II together with smaller amounts of unidentified polar material. 相似文献
10.
3-Chloro-4-methoxyaniline at concentrations of 10ppm or more in soil is converted to a mixture of 3,3′dichloro-4,4′-dimethoxyazobenzene, 3-chlorobenzoquinone-4-(3-chloro-4-methoxy)anil and its reduction product 2,3′-dichloro-4-hydroxy-4-'methoxydiphenylamine, probably by a free radical mechanism. The herbicide metoxuron, N'-(3-chloro-4-methoxyphenyl)-N,N-dimethylurea and its demethylated metabolites probably break down to the amine too slowly in soil for coupling products to be detected. 3-Chloro-4-methoxyacetanilide at 25 ppm rapidly gives rise to amine coupling products in soil slurries and ethyl N-(3-chloro-4-methoxyphenyl)carbamate does so after two months in the slurries. 相似文献
11.
T.R. Roberts 《Pesticide biochemistry and physiology》1977,7(4):378-390
The metabolism of the wild oat herbicide, flamprop-isopropyl, [Barnon, isopropyl (±) N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate] in barley grown to maturity has been examined under glass-house and outdoor conditions. [14C]Flamprop-isopropyl labeled separately in two positions was used. The major metabolic route of the herbicide was by hydrolysis to the corresponding carboxylic acid, II, which occurred in free and conjugated forms. Flamprop-isopropyl also underwent hydroxylation in the 3 and 4 positions of the benzoyl group, and the 3-hydroxybenzoyl analogue of II was detected. The hydroxylated metabolites were also present in the plants as conjugates. Additional minor metabolites detected only in glass-house samples were N-benzoyl-3-chloro-4-fluoroaniline, 2-[3-chloro-4-fluorophenylamino]-propionic acid, and benzoic acid. The soil in which the plants were grown received part of the spray application of the herbicide. Residues in the 0–10-cm layer at barley harvest comprised the unchanged herbicide, the carboxylic acid II, and unidentified polar material. 相似文献
12.
The penetration and degradation of six pyrethroids were examined in the twospotted spider mite, Tetranychus urticae Koch, and the results were related to their toxicity as measured by inhibition of respiration using the Warburg technique and mortality using the slide-dip bioassay. FMC-54800 [1,1′-biphenyl-3ylmethyl cis-3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylate] was the most toxic pyrethroid to the mites based on both respiration and mortality studies. It and flucythrinate had the highest pharmacokinetic efficiency as determined by delivery and maintenance of internal levels of parent compounds. Permethrin, fenvalerate, and fluvalinate were intermediate in pharmacokinetic efficiency, whereas cypermethrin was significantly lower. The highest intrinsic activity, as estimated by the percentage inhibition of respiration per microgram of internal parent, was possessed by cypermethrin and FMC-54800. Fenvalerate and fluvalinate had intermediate levels, while permethrin and flucythrinate had significantly lower capacities to inhibit respiration. The combination of relatively high pharmacokinetic efficiency and intrinsic activity of FMC-54800 appeared to be responsible for its high toxicity. In addition to these findings, differences in the kinetics for cis and trans isomers were observed for permethrin but not cypermethrin. This study has yielded evidence that acaricidal activity of pyrethroids can be enhanced by optimizing the structure for increased pharmacokinetic efficiency and increased intrinsic activity. 相似文献
13.
14.
The ability of o,p′DDT to bind to the 8S moiety in the uterine cytosol or to interfere with the binding of 3H-estradiol-17β (3H-E2) to that binding component was investigated utilizing a 10–30% sucrose gradient sedimentation analysis. Attempts to demonstrate the binding of radiolabeled o,p′DDT to the 8S receptor in the mouse and rabbit were not successful, presumably due to the relatively low specific activity of the radiolabeled o,p′DDT, however, binding to the “nonspecific” 4S site(s) was detected. On the other hand, the addition of nonlabeled o,p′DDT inhibited the binding of 3H-E2 to the 8S receptor. Thus, o,p′DDT (2 μM) suppressed by 58% the binding of 3H-E2 (2 nM) in the 8S region in ovariectomized adult mice. Similarly, in immature rats three concentrations of o,p′DDT (16, 32, and 96 μM) inhibited by 39.5, 52.9, and 59.7% respectively, the binding of 3H-E2 (2.8 nM). Similar results were obtained with uterine preparations from mature rats. However, the suppression of binding of 3H-E2 in the 8S region resulted in an increased binding in the 3–4S region.A Scatchard plot analysis of the binding of 3H-E2 in the presence of o,p′DDT revealed the same number of binding sites as in the absence of o,p′DDT, indicating that o,p′DDT did not “destroy” the binding capacity. Also, this analysis revealed that o,p′DDT merely caused a decrease in the ratio of the bound to free E2, indicating that o,p′DDT binds to the receptor and thus interferes with E2 binding.In addition, our observations that the administration of o,p′DDT to immature female rats causes a marked increase in the levels of the uterine nuclear binding sites (nuclear estogren receptor) is a further indication that o,p′DDT acts as a typical estrogenic compound. However, whether o,p′DDT has antiestrogenic activity as well has not been established. 相似文献
15.
The effects of the herbicide, isopropyl-3-chlorocarbanilate, and its hydroxylated metabolites, isopropyl-5-chloro-2-hydroxycarbanilate and isopropyl-3-chloro-4-hydroxycarbanilate, upon NADH oxidation, Pi uptake or release, and ATP formation were studied in corn mitochondria. The results indicated that 0.1 mM isopropyl-3-chlorocarbanilate and the 2-hydroxy-metabolite inhibited NADH oxidation by 30% whereas only the 2-hydroxy-metabolite inhibited NADH-linked ATP formation (85–100%). Dinitrophenol and the 2-hydroxy-metabolite exerted similar effects upon respiration, phosphorylation, and ATPase activity. The 4-hydroxy-metabolite (0.1 mM) exerted no effect upon respiration, phosphorylation, or ATPase activity. The β-O-glucoside conjugates of the hydroxymetabolities of isopropyl-3-chlorocarbanilate did not inhibit NADH-linked respiration or phosphorylation at 0.1 mM concentrations. Comparative studies with corn, cucumber, and soybean mitochondria indicated that the parent herbicide and its metabolites affected respiration and phosphorylation activities in a similar manner. 相似文献
16.
The firefly luciferase ATP assay was inhibited by the herbicide, isopropyl-3-chlorocarbanilate (I), and by two of its hydroxylated metabolites, isopropyl-5-chloro-2-hydroxycarbanilate (II) and isopropyl-3-chloro-4-hydroxycarbanilate (III). The β-O-glucosides of II and III reversed the inhibition of luciferase. Compounds I and II were linear noncompetitive inhibitors in respect to ATP (Ki ? 20 μM, each) and were linear competive inhibitors in respect to d-luciferin (Ki ? 6 μM, each). Compound III was a linear competitive inhibitor in respect to both ATP and d-luciferin (Ki ? 1 and 6 μM, respectively). The inhibition caused by III appeared to remain competitive for both substrates when AMP was added to the system, but the inhibition exhibited by III with respect to ATP and d-luciferin was more effective (Ki ? 0.5 μM, each). The effects of compounds I, II, and III upon the firefly luciferase ATP assay are discussed, and a relationship between the firefly system and plant susceptibility to compound I is proposed. 相似文献
17.
The degradation of the wild oat herbicide flamprop-methyl [MATAVEN, methyl (±)-N-benzoyl-N-(3-chloro-4-fluorophenyl)-2-aminopropionate] was studied in soils stored under anaerobic conditions. Comparative experiments were carried out in which soil was either covered with water or stored in an atmosphere of nitrogen. Under these anaerobic conditions, the major product was the carboxylic acid analogue (II) of flamprop-methyl, which was also a major degradation product formed in soil stored under aerobic conditions. However, the 2-, 3-, and 4-hydroxy-benzoyl analogues of II were also detected in soils stored under nitrogen or water and they were present in highest concentrations in the waterlogged soil. A further new product was also detected in waterlogged soil and it was shown to be N-benzoyl-N-(3-chloro-4-hydroxyphenyl)-2-aminopropionic acid. Although no hydroxylated derivatives of flamprop-methyl were detected in soils stored under aerobic conditions, it is possible that they were formed but underwent further degradation. 相似文献
18.
A variety of thiophene carboxamide compounds have been synthesized and tested on the succinate dehydrogenase complex (SDC) in mitochondria from a wild-type strain and carboxin-resistant strains of Ustilago maydis (corn smut). The site of action of thiophene carboxamides is identical to that of carboxin (5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide) and thenoyltrifluoroacetone, that is, the succinate-ubiquinone reductase (complex II) span in the mitochondrial electron transfer chain. This investigation reveals new molecular structures which are strong inhibitors of wild-type and carboxin-resistant SDCs. The 5-amino analog of the parent anilide, 3-methylthiophene-2-carboxanilide (I), proved to be an especially potent inhibitor of the wild-type SDC (I50, 0.019 μM). Analogs of (I) such as 4′-carboethoxy, 4′-nbutyl, 4′-phenyl, and 4′-benzoyl were negatively correlated in activity to the carboxanilide (I) with respect to resistance level. A number of structures showed considerable selectivity for mutated SDCs from both highly and (particularly) moderately carboxin-resistant SDCs of U. maydis, markedly lowering the resistance level, i.e., the degree of resistance. Thus, in addition to the oxathiins, specific structural groups of thiophene carboxamides can also alleviate or reverse the effect of carboxin-selected mutation with reference to inhibition of the SDC. Of important significance was the finding that molecular selectivity for mutated, carboxin-resistant SDCs can be influenced by replacement of an oxathiin by a thiophene heterocyclic ring as well as by the substitutive group on the amide nitrogen, permitting different categories of mutant types and even mutants within a single category to be distinguished from one another. With all the structural combinations available, it appears quite possible, in terms of inhibition, to overcome any type of mutation in a fungal SDC which arises through selection by carboxin or other carboxamide compounds. A reasonable correlation generally exists between inhibition by thiophene carboxamides of the SDC and sporidial growth of wild-type and carboxin-resistant strains of U. maydis. A permeability barrier to 4′-substituted analogs of (I) was encountered in the wild-type strain but not mutant strains. Excellent protectant activity against bean rust (Uromyces phaseoli) was obtained with the 3′-nhexyl, 3′-nhexyloxy, and 4′-phenoxy analogs of (I). 相似文献
19.
M.C. Giardina M. de Agazio M.T. Giardi R. Buffone 《Pesticide biochemistry and physiology》1983,19(1):11-14
The action of atrazine and its biodegradation products on the membrane transport of potassium in roots was evaluated in both sensitive and resistant plants. Excised roots of maize and oat showed inhibition of potassium uptake efficiency in the presence of 1.4 × 10?4M atrazine and 1.4 × 10?4M deethylated atrazine. Other biodegradation products such as 2-chloro-4-amino-6-ethylamino-1,3,5-triazine,2-chloro-4,6-,bisamino-1,3,5-triazine, and 2-chloro-4-amino-1,3,5-triazine showed no inhibitory effect on the K+ uptake capacity. Two maize hybrids showing different uptake efficiency were inhibited differently by atrazine. We suggest that atrazine and deethylated atrazine inhibited the K+ transport interacting directly with the plant cell membranes without discerning between resistant and sensitive plants. 相似文献
20.
The effects of p,p′-DDT and four of its analogs on electrical activity in the central nervous system of the cockroach, Periplaneta americana (L.), were investigated. Cockroaches were injected intraabdominally with an organochlorine compound at LD50 96-hr doses (except for p,p′-DDE). Extracellular recordings were made from the central nervous system at 1 hr, 24 hr, or 3 weeks postinjection. p,p′-DDT, methoxychlor, and p,p′-DDD induced behavioral changes (tremors, jitters, hyperexcitability) and repetitive firing in the central nervous system prior to 1 hr postinjection. By 24 hr postinjection, most behavioral signs of poisoning had disappeared, though repetitive firing could still be readily elicited in the central nervous system. Cockroaches injected with o,p′-DDT, however, usually required about 48 hr before overt signs of poisoning became apparent. Cockroaches treated with p,p′-DDT or o,p′-DDT behaved normally at 3 weeks postinjection but still displayed a significant occurrence of repetitive firing in the central nervous system. A mechanism is proposed to explain how a cockroach might recover behaviorally from a sublethal dose of an organochlorine compound but still display repetitive firing in its central nervous system. A direct “cause and effect” relationship between repetitive firing in the central nervous system and mortality (and external signs of poisoning) is therefore questioned. 相似文献