共查询到20条相似文献，搜索用时 31 毫秒
1.
《Pesticide biochemistry and physiology》1986,25(2):188-204
Carboxin (5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide) and the thiophene compound 3-methylthiophene-2-carboxanilide (I), inhibit succinate oxidation (succinate-ubiquinone reductase; complex II) in mitochondria from a wild-type strain and three mutant, carboxin-resistant strains of Aspergillus nidulans. Studies by White et al. [Pestic. Biochem. Physiol. 9, 165–182 (1978)] showed that certain oxathiin carboxamide structures were selectively active against particular mutated succinate dehydrogenase complexes (SDCs) of A. nidulans, significantly lowering the level of resistance. Although no oxathiin carboxamides were found to be negatively correlated to carboxin with respect to their effect on SDCs from wild-type and mutant strains of A. nidulans, several could distinguish between moderately and highly carboxin-resistant SDCs and, as shown in the present study, between the two non-allelic highly carboxin-resistant mutants cbx B-28 and cbx C-34. Variation in the molecular structure of thiophene carboxamides can also affect the phenotypic expression of mutations to carboxin resistance in the SDC of A. nidulans, with certain structures being capable of differentiating between moderately and highly carboxin-resistant mutated SDCs. With a moderately carboxin-resistant mutant, cbx A-17, a wide structural variety of thiophene carboxamides, e.g., the 2′-methyl, 2′-benzoyl, 3′-phenoxy, 4′-nbutyl and the N-nhexyl derivatives of (I), did exhibit negative activity correlation to the parent anilide (I). However, with the possible exception of the 4′-nbutyl and 4′-noctyloxy analogs of (I), thiophene carboxamides showed no negative activity correlation to carboxin or (I) for the highly carboxin-resistant mutants cbx B-28 and cbx C-34. As with carboxin-resistant mutants of Ustilago maydis [Pestic. Biochem. Physiol. 14, 26–40 (1980)], molecular selectivity for mutated carboxin-resistant SDCs of A. nidulans can be markedly influenced by substitution of an oxathiin with a thiophene heterocyclic ring. None of the thiophene carboxamides were considerably toxic to mycelial growth of the wild-type and carboxin-resistant strains of A. nidulans with permeability rather than affinity for the SDC appearing to be the limiting factor. For certain derivatives such as the 5-amino analog of (I), SDC activity and cell growth were inhibited similarly. Several thiophene carboxamides [2′-phenyl, 4′-phenoxy, and N-ndecyl analogs of (I)] showed specificity for the highly carboxin-resistant mutants cbx B-28 and cbx C-34. Thiophene carboxamide structures have been identified which inhibit spore germination of non-Basidiomycete plant pathogens, particularly Phytophthora infestans and Verticillium dahliae. In vivo experiments with late blight (P. infestans) on tomato plants have shown that a few thiophene carboxamides, e.g., the 3′-nbutyl analog of (I) give satisfactory protectant activity. 相似文献
2.
The systemic fungicide carboxin (5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide) and structurally related analogs are powerful inhibitors of succinate oxidation in mitochondria isolated from a variety of sources. The site of action which is, apparently, also that for thenoyltrifluoracetone, is in the complex II (succinate-ubiquinone reductase) region of the mitochondrial electron transfer chain. The succinic dehydrogenase complex (SDC) in mitochondria from carbon-resistant mutant strains of Ustilago maydis and Aspergillus nidulans is resistant to the fungicide in vitro. The current study shows that certain oxathiin carboxamides are selectively active against particular mutated SDCs of U. maydis and A. nidulans. Molecular structures affecting the phenotypic expression of mutation to carboxin resistance in U. maydis do not appear to affect similarly such expression in A. nidulans and vice versa. Of particular interest was the discovery of oxathiin carboxamides, e.g., 4′-phenylcarboxin, which were more inhibitory to the enzyme complex from one category of carboxin-resistant mutants of U. maydis than from the wild-type strain. Although such negative correlation between carboxin and other carboxin analogs has not been observed in studies with other categories of mutants, structures which drastically lower the resistance level were found in all cases. It appears that for any given mutation affecting carboxin sensitivity of the SDC in fungi, a specific structural group of carboxamides (or even a specific carboxamide) may be found which will alleviate or reverse the effect of the mutation in terms of inhibition of the SDC. If the mutations alter a protein receptor site for carboxamides, such mutations might be expected to influence the binding of carboxins of different structure. In essence, then, different molecular structures can “recognize” different alterations in the mutated enzyme complex and inhibit effectively. With few exceptions, the inhibition by carboxamides of cell growth of wild-type and carboxin-resistant strains of U. maydis and A. nidulans closely paralleded the inhibition of their respective SDCs. Although the few analogs tested were found unable to control corn smut systemically in seedlings artificially inoculated with compatible carboxin-resistant strains, control of naturally occurring carboxin-resistant strains of pathogenic fungi may be possible using particular structural analogs of carboxin which selectively inhibit the mutant organisms. 相似文献
3.
The systemic fungicide, carboxin (5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide) and a variety of carboxamide compounds exhibit a marked specificity for Basidiomycete fungi. This unique specificity resides in the mitochondrial succinic dehydrogenase complex (SDC) of sensitive Basidiomycetes such as Ustilago maydis, the corn smut fungus. The present study examines in detail the structure-activity relationships of 93 carboxamide compounds and the SDC of two carboxin-sensitive organisms, U. maydis and a Basidiomycetous yeast, Cryptococcus laurentii. It has been possible to elucidate substantially the requirement in molecular structure needed for inhibition of the mitochondrial SDC. With few exceptions, a good correlation exists between the inhibitory activity of carboxamides towards the SDC of U. maydis and C. laurentii and the inhibition of growth of carboxamide-sensitive fungi, both in vitro and in vivo on the diseased plant. The structure-activity results were used as a basis for the synthesis of new, fungicidally-active carboxamides. The compounds found to be most active against the mycelial growth of Rhizoctonia solani were also tested on spore germination or mycelial growth of non-Basidiomycete fungi. Three carboxanilides (3-methyl-thiophene-2-carboxanilide, 3′-methyl-2-methylbenzanilide and 3′-methyl-2-ethylbenzanilide) had a fungitoxic spectrum which extended beyond Basidiomycetes. The spectrum of fungicidal activity of carboxanilides appears to be altered not only by substitution in the aniline ring, but by the nature of the ring attached to the carbonyl. No correlation was found between the inhibitory activity of oxathiins and benzanilides and their calculated partition coefficients. 相似文献
4.
Carboxin (5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide) was tested for its effect on the activities of mitochondria from several fungi, pinto beans and rat liver. Succinate oxidation by mitochondria from the sensitive fungus Ustilago maydis was inhibited by low concentrations of carboxin, the Ki being 0.32 μM. The inhibition was of a noncompetitive nature. Succinate oxidation was also inhibited in the mitochondria from other sources but not to the extent as in those from U. maydis. Carboxin had little effect on the oxidation of reduced nicotinamide adenine dinucleotide. The dioxide of carboxin, oxycarboxin, was not as effective in inhibiting succinate oxidation as was carboxin, but was more effective than the monoxide. Carboxin did not appear to uncouple oxidative phosphorylation in the presence of succinate in tightly coupled rat liver mitochondria but did decrease the respiratory control ratio. Carboxin was ineffective in releasing oligomycin inhibition in coupled rat liver mitochondria while dinitrophenol and salicylanilide were effective in this respect. It is believed that carboxin inhibits mitochondrial respiration at or close to the site of succinate oxidation and does not greatly affect the remaining portion of the electron transport system or the coupled phosphorylation reactions. 相似文献
5.
Respiration and growth of a diploid strain of Ustilago maydis, heterozygous at the oxr-1 locus for resistance to carboxin and carboxin analogs, were less sensitive to the fungicide than the corresponding processes in the wild type haploid. Data on the inhibition of succinate-2,6-dichlorophenolindophenol reductase indicate that the mitochondria of the heterozygous diploid probably contain a mixture of carboxin-sensitive and carboxin-resistant succinic dehydrogenase complexes. This hypothesis is supported by the results of temperature aging experiments: When mitochondria of the heterozygous diploid were subjected to incubation at 30°C which destroyed the enzyme activity of mitochondria from the mutant haploid, the remaining succinate-2,6-dichlorophenol-indophenol reductase activity exhibited a carboxin sensitivity similar to that of mitochondria from the wild type haploid.Carboxin gave very good control of corn smut in seedlings artificially inoculated with two wild type compatible strains but not when both strains were mutant for carboxin resistance, which indicates high resistance in the dicaryon. In a heterozygous cross, the dicaryon seemed to exhibit considerable resistance, if sufficient time was allowed for its formation between inoculation and carboxin treatment of soil. 相似文献
6.
Succinoxidase activity of mitochondria from an antimycin A-sensitive (ants) mutant of Ustilago maydis is approximately five times less sensitive to the fungicide carboxin than that of mitochondria from wild-type cells. The antimycin A sensitivity is due to the absence of an alternative electron transport pathway in mitochondria obtained from mutant cells grown in control medium. The same mutant, however, develops high rates of alternative respiration if grown in the presence of chloramphenicol. Substrate and oxygen affinity as well as resistance to hydroxamates indicate that this respiration is mediated by only one mitochondrial electron transport pathway, similar to the inducible system described earlier in wild-type mitochondria. Induction appears to be regulated by the activity of the cytochrome pathway. The absence of the constitutive system from the ants mutant mitochondria which are resistant to carboxin, a selective inhibitor of the succinate dehydrogenase complex, supports the view that this system must be related to succinic dehydrogenase. 相似文献
7.
《Pesticide biochemistry and physiology》1986,25(2):163-168
A series of carboxin-like compounds, the N-methylpyrazole carboxanilides and their mono- and dimethyl derivatives have been assayed as inhibitors of succinate dehydrogenase enzyme complexes (SDCs) isolated from Ustilago maydis, Rhizoctonia solani, Gaeumanomyces graminis, and Fusarium oxysporum. The pattern of inhibitory activity within the series was broadly similar for each of the fungi although minor differences indicated some structural variation between the enzyme complexes. There was a general correlation between inhibition of the SDCs isolated from R. solani and G. graminis and inhibition of mycelial growth of these same organisms which was consistent with the primary mode of action of these compounds being interference with mitochondrial electron transport. No such correlation was evident with F. oxysporum, where some of the compounds showed activity against the SDC but none had any effect on fungal growth. This suggests that if SDC inhibitory activity is the primary determinant of the anti-fungal activity of these compounds it does not necessarily determine their anti-fungal specificity: some possible explanations are offered. 相似文献
8.
Aspergillus niger converts the herbicide 3′-chloro-2-methyl-p-valerotoluidide (solan) to 3′-chloro-4′-methylacetanilide and the fungicide 2,5-dimethylfuran-3-carboxanilide to acetanilide. The metabolites were formed by hydrolysis with an aryl acylamidase, followed by subsequent acetylation resulting in the corresponding acetanilides. Their structures were elucidated by mass spectrometric analysis and confirmed by comparison with synthetic compounds. 相似文献
9.
10.
To investigate different control measures against the diseases in winter rye several trials were done in the German federal states. As a result from these trials the brown rust,Puccinia recondita f. sp.secalis, was the disease with the most negative influence on the yield. The brown rust occurrence at different times on the top three leaves depend on the winter and spring weather. It should be verify whether the protective use of fungicide mixtures with the new carboxamides active ingredient benefits the curative use (disease onset) in terms of achieved efficiency againstP. recondita. It can be stated that the action threshold does not need to be changed when using fungicide mixtures with carboxamides. Regarding the duration of the fungicide efficacy againstP. recondita an order in increasingly levels of efficiency could be determinate. The order is, from lowest to highest, azole fungicides, strobilurin-azole compounds, azole carboxamide compounds, and azole-carboxamide strobilurin mixtures. Due to the variability in the values of the individual test sites in the experimental series the tendency could be confirmed, however, no statistical significant differences between the various mixtures could be determined. The new carboxamides enrich the possibilities of targeted anti-resistance strategy againstP. recondita in winter rye. These trials results are introduced into recommendations for agricultural practice. 相似文献
11.
The metabolism of cis-2,5-dimethylpyrrolidine-1-carboxanilide was studied in rats, rabbits, guinea-pigs and mice. The major metabolite in all species was cis-4′-hydroxy-2,5-dimethylpyrrolidine-1-carboxanilide, both free and as glucuronide and sulphate conjugates. About 95% of the compound was absorbed from the gut; over a 3-day period, about 50% of the administered dose was excreted in urine and about 27% in faeces. 相似文献
12.
An ergosterol-deficient mutant of Ustilago maydis was compared to the wild type in regard to morphology, growth rate, lipid content, and sensitivity to ergosterol biosynthetic inhibitors. Morphology of mutant sporidia is abnormal and resembles that of fenarimol-treated wild-type sporidia. Doubling time of mutant sporidia is 6.3 hr compared to 2.5 hr for the wild type. The mutant produces 24-methylenedihydrolanosterol, obtusifoliol, and 14α-methylfecosterol; ergosterol is absent. The sterols of the mutant are the same as those which accumulate in wild-type sporidia treated with the sterol C-14 demethylation inhibitors fenarimol, etaconazole, and miconazole. The level of free fatty acids is higher in the mutant than in wild-type cells. Growth of mutant sporidia is not inhibited by fenarimol, etaconazole, and miconazole, or by the sterol Δ14-reductase inhibitor azasterol A25822B at low concentrations which inhibit growth of wild-type sporidia. The residual growth rate of wild-type sporidia treated with low concentrations of the sterol C-14 demethylation inhibitors is about the same as that of untreated mutant sporidia. Therefore, the mutant would not be recognized as resistant in a wild-type population. The mutant is deficient in sterol C-14 demethylation and is similar in all properties studied to wild-type sporidia treated with sterol C-14 demethylation inhibitors. These findings support the contention that inhibition of sterol C-14 demethylation in U. maydis is the primary mode of toxicity of fenarimol, etaconazole, and miconazole. A secondary mode of toxicity is evident for miconazole and etaconazole at higher concentrations but is doubtful for fenarimol. 相似文献
13.
Hiroyuki Katsuta Tomomi Shirakawa Miyuki Kawashima Shinichi Banba 《Journal of Pesticide Science》2021,46(2):229
To investigate the effects of bioisosteric replacement of the phenyl group with the thienyl group, N-phenylcarboxamide and three regioisomers of N-(substituted-thienyl)carboxamide were synthesized. The inhibitory activity on the succinate dehydrogenase prepared from the gray mold Botrytis cinerea as well as the fungicidal activity against B. cinerea were evaluated. Two isomers, N-(2-substituted-3-thienyl)carboxamide and N-(4-substituted-3-thienyl)carboxamide exhibited the same level of activity as the phenyl derivative, whereas N-(3-substituted-2-thienyl)carboxamide exhibited lower activity than the phenyl derivative, suggesting that the 2-substituted-3-thienyl and 4-substituted-3-thienyl groups functioned as bioisosteres of the phenyl group in N-phenylcarboxamide, but the other did not. 相似文献
14.
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
15.
[14C]Buturon, a urea herbicide, was sprayed on soil and winter wheat as an aqueous formulation (2.98 kg/ha) under outdoor conditions. Three months after application, a total of 49.2% of the applied radiocarbon was recovered: 46.9% in the soil, 0.3% in the leaching water (depth > 50 cm), and 2.0% in the plants. Radioactive residues in the soil were distributed to a depth of 50 cm and decreased with increasing depth of the soil. An average of 47% of the radioactivity present in the soil could be extracted with cold chloroform; by this extraction method, the formation of artefacts was avoided. Between one and two thirds of the extracted radioactivity was unchanged buturon. In the soil extracts, the following eight conversion products were isolated and identified by combined gas chromatography/mass spectrometry: N-(p-chlorophenyl)-N-methyl-O-methyl carbamate; N-(p-chlorophenyl)-O-methyl carbamate; N-(p-chlorophenyl)-N′-methyl-N′-isobutenyl-urea; N-(p-chlorophenyl)-N′-methyl-urea, N-(p-chlorophenyl)-N′-methyl-N′-isobutenylol-urea; p-chloroaniline in “biologically bound” form; N-(p-chlorophenyl)-N′-methyl-N′-methoxyisobutenyl-urea; and N-(p-chlorophenyl)-N′-methyl-N′-ethoxyisobutenyl-urea. In the leaching water, which contained only 0.005–0.006 mg/liter of radioactive substances, the following three conversion products were isolated and identified by gas chromatography/mass spectrometry: p-chloroformanilide; N-(p-chlorophenyl)-N-methyl-O-methyl carbamate; and an N-hydroxyphenyl-N′-methyl-N′-isobutinyl-urea. The results are discussed in relation to the factors responsible for the formation of these products. 相似文献
16.
ABSTRACT Two carboxin-resistant field isolates of Ustilago nuda from Europe were crossed with a carboxin-sensitive field isolate from North America. Meiotic tetrads isolated from germinating F(1) teliospores of one of the hybrids were tested for carboxin resistance and mating type. Carboxin resistance was shown to be controlled by a single gene (CBX1R), because a 1:1 segregation of carboxin resistance was observed in all 27 tetrads. Tetrad analysis indicated that the loci for carboxin resistance (Cbx1) and mating type (MAT1) segregate independently but may be located on the same chromosome. Tetrad analysis was not possible with the F(1) hybrid of he other field isolate, and its resistance cannot yet be attributed to CBX1R. Carboxin resistance was qualitatively dominant to sensitivity in vitro, as demonstrated by triad analysis of germinating F(1) teliospores. Quantitative in planta infection percents supported the conclusion that CBX1R is dominant, although incompletely, in the F(1) hybrid of one of the field isolates. Also, fewer than expected carboxin-sensitive F(2) individuals were observed in planta. However, inoculations of host plants with U. nuda have resulted in similar, unexpected variation in the past. 相似文献
17.
The relationships between the development of disease symptoms ofPuccinia sorghi, Exserohilum turcicum andHelminthosporium maydis on susceptible sweet corn plants, and the water status of the plants, were studied. At a relative water content (RWC) of 75% the development of sori ofP. sorghi, and the leaf area infected byE. turcicum andH. maydis, were inhibited by 38, 75 and 84%, respectively, as compared with the control plants (RWC = 100%).P. sorghi andH. maydis were not inhibited by a slight decrease in the RWC (96%), but development of leaf area infected byE. turcicum was inhibited by 33%.P. sorghi seemed to be better adapted to relatively high water deficiency in the host plants thanH. maydis orE. turcicum. 相似文献
18.
A model has been used to design novel pyrazole methanesulfonates. The pyrazole carboxamide methanesulfonates demonstrated insecticidal activity with low levels of acute mammalian toxicity. The amides formed from amines with α-branching (e.g. isopropyl and sec-butyl) demonstrated the highest level of activity. The model has also been used to design novel pyrazole sulfonamide methanesulfonates with very high levels of insecticidal activity. Most of the sulfonamides also possessed significant acute mammalian toxicity. Rice paddy field testing of the carboxamides on field population hoppers gave poor results. © 1997 SCI 相似文献
19.
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
20.
Action of methyl-2-benzimidazolecarbamate (MBC), a breakdown product of benomyl, was studied in synchronous cultures of Ustilago maydis and Saccharomyces cerevesiae. Cells treated with MBC developed similarly to control cells until the two portions of the doublets (joined mother and daughter “cells”) were morphologically equivalent. At this point development of the treated cells ceased but control doublets separated to form two new cells. The compound did not prevent DNA synthesis during the first cell cycle of synchronized S. cerevesiae cells but did prevent completion of cell division, as it did also in synchronized U. maydis sporidia which already contained the DNA complement needed for completion of the first division. Mitosis did not go to completion in MBC-treated cells so the doublets formed contained only a single compact nucleus. The effect of MBC markedly resembles mitotic arrest caused by colchicine and isopropyl N-phenylcarbamate in higher plants and griseofulvin in the fungus Aspergillus nidulans. Inhibition of DNA synthesis in U. maydis and inhibition of cytokinesis in both organisms studied are secondary effects attributable to mitotic failure.A volatile compound toxic to U. maydis and S. cerevesiae was demonstrated in air over moistened benomyl. Hexane, through which such air samples were passed, or hexane extracts of aqueous suspensions of benomyl contained a substance having the same ir spectrum and retention time in two gas chromatographic systems as butyl isocyanate (BIC).BIC inhibited respiration of U. maydis and S. cerevesiae in a manner similar to benomyl. Benomyl partially inhibited respiration of subcellular particles from both organisms. MBC had essentially no effect on whole cell or subcellular particle respiration of either organism. Toxicity of benomyl preparations is not attributed to “benomyl” as such, but to two breakdown products, MBC and BIC. Therefore, differential effects of benomyl preparations and of MBC on growth and metabolism in fungi should be ascribed to BIC. 相似文献