Absorption of methyl benzimidazol-2-yl carbamate (carbendazim) by corn roots

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).     

Metabolic conversion of methyl benzimidazol-2-yl carbamate (MBC) in Aspergillus nidulans

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.     

Antimitotic activity of methyl benzimidazol-2-yl carbamate (MBC) in Aspergillus nidulans

Mitosis in germ tubes of Aspergillus nidulans was inhibited directly upon addition of methyl benzimidazol-2-yl carbamate to liquid cultures, whereas dry weight increase and DNA and RNA synthesis were progressively inhibited only after a few hours. Microscopic observation of the organism, grown on malt extract agar containing MBC revealed abnormal chromatin configurations. The possible mode of action of MBC through interference with spindle formation is discussed.     

A biochemical mechanism for the conversion of thiophanate-methyl into methyl benzimidazol-2-YL carbamate (MBC) in plant tissue

Thin slices of potato tuber greatly accelerated the conversion of thiophanatemethyl into MBC. This was also observed when thiophanate-methyl was incubated with homogenates of apple, potato or with sap pressed from cucumber seedlings. Studies with cell-free extracts and crude enzyme preparations from potato tuber strongly suggested that in the presence of the enzyme polyphenol oxidase (EC 1.10.3.1) together with a suitable substrate, like DOPA or chlorogenic acid, the conversion of thiophanate-methyl into MBC is accelerated. Since it was found that some o- and p-quinones without polyphenol oxidase also could accelerate this conversion, it was concluded that unstable quinones generated by polyphenol oxidase from diphenol substrates might be the compounds which catalyze the formation of MBC from thiophanate-methyl.     

氨基甲酸-2-氯吡啶-5-甲酯化合物的合成与抑菌活性

以芳香硝基化合物、2-氯-5-吡啶甲醇和一氧化碳为原料,在Pd-Fe/TiO2催化下进行羰基化反应,合成了11个新型氨基甲酸-2-氯吡啶-5-甲酯化合物,其结构经 1H NMR和MS表征。初步抑菌活性测定结果表明:在50 mg/L下,大多数目标化合物对4种供试病原菌具有一定的抑制活性,其中化合物 3f (4-甲氧基苯基氨基甲酸-2-氯吡啶-5-甲酯、3h (2,4-二氯苯基氨基甲酸-2-氯吡啶-5-甲酯)和 3j (3,4-二氯苯基氨基甲酸-2-氯吡啶-5-甲酯)对小麦赤霉病菌Gibberella zeae的抑制率达77.3%以上, 3f 对苹果轮纹病菌Physalospora piricola的抑制率达82.5%,与对照药多菌灵接近;所有化合物在50 mg/L下对番茄灰霉病菌Botrytis cinerea的抑制活性均优于对照药多菌灵。     

Photochemical transformation of thiophanate-methyl and thiophanate to alkyl benzimidazol-2-yl carbamates

The systemic fungicides thiophanate-methyl (TPM) and thiophanate (TPE) were transformed in aqueous solutions on glass by irradiation with u.v. and sunlight to the more effective fungitoxic substances methyl benzimidazol-2-yl carbamate (MBC) and ethyl benzimidazol-2-yl carbamate (EBC), respectively. The thiophanate fungicides were not converted when incubated in the dark. The photochemical transformation of TPM and TPE to the corresponding alkyl benzimidazol-2-yl carbamates increased with the exposure time of u.v. irradiation. However, no light catalysed reactions occurred when both fungicides were irradiated with u.v. light in the solid state. The residue of TPM and TPE on leaves of cotton plants following spray application were transformed by the energy of sunlight to the more fungitoxic MBC and EBC.     

Uptake and translocation of carpropamid in rice (Oryza sativa L)

Translocation of the antiblast compound, carpropamid, was investigated in rice using [¹⁴C]carpropamid. When applied to the seed, carpropamid was not only readily absorbed but was translocated to different parts of the seedlings emerging from treated seeds. A substantial portion of fungicide appeared to be exuded onto the leaf surface. In 21‐day‐old plants grown from [¹⁴C]carpropamid‐treated seeds, 27.2% of the radioactivity isolated from leaves was present on the surface of lamina. This exuded fraction is probably responsible for its action as a fungal anti‐penetrant compound. Following 30‐min root dipping of 14‐day‐old seedlings, carpropamid was rapidly absorbed and translocated throughout the seedling. Its intra‐laminar distribution was uniform as determined by autoradiography. Only a small fraction (<2%) of fungicide applied to the foliage was translocated beyond the site of application within the treated leaf. Translocation was primarily apoplastic. Approximately 54% of the radioactivity recovered from leaves was in the form of carpropamid. At least seven radiolabelled metabolic products were observed by TLC. Only 8.3% of radioactivity applied through the seeds could be recovered from 21‐day‐old seedlings. © 2001 Society of Chemical Industry     

Metabolism of 2,3-dihydro-2,2-dimethyl-7-benzofuranyl (di-n-butylaminosulfenyl)(methyl)carbamate and 2,3-dihydro-2,2-dimethyl-7-benzofuranyl (morpholinosulfenyl)(methyl)carbamate in cotton and corn plants

The absorption, translocation, and metabolism of two new, selectively toxic derivatives of carbofuran, 2,3-dihydro-2,2-dimethyl-7-benzofuranyl (di-n-butylaminosulfenyl)(methyl)carbamate and 2,3-dihydro-2,2-dimethyl-7-benzofuranyl (morpholinosulfenyl)(methyl)carbamate, were studied in cotton and corn plants 1, 3, 6, and 10 days following both stem injection and foliage treatment. Both carbamates were readily translocated to all plant parts following stem injection, but translocation following leaf application was restricted to within the leaf. In cotton plants, the dibutylaminosulfenyl derivative was easily hydrolyzed to form carbofuran which, in turn, was oxidized at the 3-position of the ring and the N-methyl group. These oxidized metabolites were then converted to plant conjugates. Major metabolites were carbofuran and 3-hydroxy-carbofuran followed by 3-keto-carbofuran phenol and N-hydroxymethyl-carbofuran. Five minor metabolites also were detected. In corn plants, the dibutylaminosulfenyl derivative gave the same metabolites, although the metabolism rate was significantly slower in corn relative to cotton. Overall, the results showed that there were no fundamental differences in the metabolism of the morpholinosulfenyl and dibutylaminosulfenyl derivatives. The stability of both carbamate derivatives in different solvent systems also was investigated.     

Uptake, translocation and fate of 2,4-D and chlorsulfuron in Silene vulgaris (Moench) Garcke

Experiments were conducted to examine the up take, translocation and metabolism by S. vulgaris of two distinctly different herbicides: 2,4-D, a phenoxyalkanoic acid with growth regulator activity to which this species exhibits complete tolerance, and chlorsulfuron, a sul-fonylurea to which S. vulgaris is highly sensitive. Despite their structural dissimilarities 2,4-D and chlorsulfuron was readily absorbed by S. vulgaris with 65 and 69%, respectively, of the applied dosage being absorbed within 72 hours after treatment. Approximately 35% of the 2,4-D and 10% of the chlorsulfuron label was translocated out of the treated leaf after 72 hours. Neither herbicide accumulated in the terminal bud. Seventy-two hours after treatment 63% of the recovered ¹⁴C remained as unaltered 2,4-D in S. vulgaris, while in tomato, a 2,4-D sensitive species, 65% of the recovered ¹⁴C remained as intact herbicide. In S. vulgaris approximately 86% of the radioactivity remained as intact chlorsulfuron 72 hours after treatment compared to 12% in the tolerant wheat. The tolerance of S. vulgaris to 2,4-D could not be accounted for by limited absorption, translocation nor metabolic degradation of the herbicide. The sensitivity of S. vulgaris to chlorsulfuron would appear to be related to the inability of this species to metabolize the herbicide molecule.     

Effects of benomyl,carbendazim and thiophanates on respiration and oxidative phosphorylation of Fusarium oxysporum and Saccharomyces cerevisiae

Benomyl [methyl 1-(butylcarbamoyl)-benzimidazol-2-ylcarbamate] (350 × 10^?6 M) decreased the respiration rate of Fusarium oxysporum conidia by 50% during germination. This inhibition was maintained at least 24 h after the treatment had begun. The treatment did not modify the relation between incubation time and respiration rate. Carbendazim [methyl benzimidazol-2-ylcarbamate], thiabendazole[2-(thiazol-4-yl)benzimidazole], thiophanate [1,2-di-(3-ethoxycarbonyl-2-thioureido)benzene] and thiophanate-methyl [1,2-di-(3-methoxycarbonyl-2-thioureido)benzene] were assayed using isolated mitochondria of Saccharomyces cerevisiae. These four compounds decreased mitochondrial respiration and oxidative phosphorylation rates to different extents when they were applied at a concentration of 250 × 10^?6 M . Thiophanate-methyl was the most effective since it completely suppressed the mitochondrial respiratory control at 75 × 10^?6 M .     

Uptake and translocation of ethofumesate in sugar-beet plants

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.     

N-氰基甲基-[(苯甲酰基)(2-氯噻唑-5-基甲基)氨基乙基]砜亚胺类化合物的合成及杀虫活性

为了寻找和发现高效、广谱、低毒、低生态风险并与现有杀虫剂无交互抗性的新型杀虫剂,以2-氯-5-氯甲基噻唑为原料,经多步反应制得10个新型N-氰基甲基 砜亚胺类化合物,其结构均经核磁共振氢谱、元素分析确证。室内生物活性测试结果表明,目标化合物对桃蚜Myzus persicae具有一定的杀虫活性,其中化合物 7-1 在质量浓度为10 mg/L下对桃蚜的致死率达到80%。     

Uptake and translocation of dimefox and schradan in hops

During the 1971 growing season an experiment was carried out to study the uptake, translocation and residue levels of dimefox and schradan in hope after applying a soil drench of Terra-Sytarn (222 g/litre dimefox-20 g/litre schradan) at various times in varying concentrations. Residue analysis shows that the dimefox concentration in the hop plants reaches a peak about one week after application, which increases with the amount applied. Then a gradual breakdown sets in so that at the time of harvesting the differences between the dosages have virtually disappeared. Translocation of dimefox in the hop plant is very rapid, but the breakdown is faster at the top of the plant. Schradan concentrations were usually very low and residues at harvest time negligible.     

(4-亚甲基-5-羰基-3-四氢呋喃基)-苯甲酸甲酯衍生物的合成及其杀菌活性

为了探索天然产物Cedarmycins衍生物的结构与活性关系,以α-亚甲基-β-羟甲基-γ-丁内酯为起始原料,经过与不同取代的羧酸缩合,合成了19个新的(4-亚甲基-5-羰基-3-四氢呋喃基)-苯甲酸甲酯衍生物。杀菌活性测定结果表明,该类衍生物具有广谱的杀菌活性,尤其对水稻纹枯病菌Rhizoctonia solani和辣椒疫霉Phytophthora capsici显示出很强的杀菌活性,其中化合物2e(R=2,4-2Cl)对这2种病菌的EC50值约为1.6 mg/L。     

The use of methyl bromide and carbendazim for the control of lettuce big-vein disease

Lettuce seedlings raised in peat blocks placed on contaminated soil subsequently developed lettuce big-vein disease symptoms when grown in pots of sterilized compost. Incorporation of 0.01 g carbendazim per 4.3 cm³ peat block reduced the number of plants with disease symptoms but did not prevent root infection by Olpidium brassicae , the vector of the big-vein agent. Similar results were obtained when seedlings propagated in the absence of big-vein disease were grown in pots of contaminated soil but carbendazim was less effective when the treated blocks were planted in contaminated field plots. Methyl bromide applied at 500, 750 or 1000 kg/ha temporarily controlled the disease but re-contamination occurred and was complete after three consecutive crops.
Bromide residues in lettuce heads reached 9240 μg/g dry tissue in the first crop but fell to a maximum 772 μg/g by the third crop. Bromide residues in soil fell to natural levels over this period.     

Penetration and metabolism of 2-isopropoxyphenyl N-methyl-N-(2-methyl-4-tert-butylphenylsulfenyl) carbamate in the house fly and honeybee

The penetration and metabolism of 2 - isopropoxyphenyl N-methyl-N-(2-methyl-4-tert - butylphenylsulfenyl)carbamate or sulfenyl-propoxur was examined in the house fly and honeybee. Reduced penetration was found to be a factor contributing to the lower toxicity of sulfenyl-propoxur to the honeybee. Honeybees and house flies metabolized sulfenyl-propoxur qualitatively in a similar manner. Quantitatively, larger amounts of propoxur were found in the house fly than in the honeybee soon after treatment with sulfenyl-propoxur. The slower rate of conversion of sulfenyl-propoxur to propoxur was considered as another factor responsible for the lower toxicity of the sulfenylated derivative to bees. The high susceptibility of bees to propoxur was related to high internal amounts of unchanged propoxur found soon after treatment.     

Uptake and translocation of bleaching herbicidal compounds in radish seedlings

The relationship between the hydrophobicity of certain herbicidal compounds and the bleaching pattern caused on radish cotyledons was investigated. Seed treatment with diphenylpyridones, as well as with established herbicides, produced three types of bleaching pattern according to their hydrophobicity. The less hydrophobic compounds caused complete bleaching of both cotyledons, but the compounds with more hydrophobicity caused only partial bleaching. The critical points for whole or partial bleaching were in the range of log K_ow 4–5 (K_ow: octanol/water partition coefficient), and these values were changed slightly with their chemical classes. Uptake of compounds into the seed coat took place rapidly; these compounds were then translocated slowly from the seed coat to the embryo, namely, radicle, abaxial surface of one cotyledon and marginal areas of both cotyledons. Application of these compounds to roots resulted in initial translocation to marginal areas of both cotyledons, with subsequent translocation to the middle area. It is believed that compounds taken up into the radicle were translocated to both cotyledons in a manner similar to that following application to roots. These effects following uptake by seeds can be used as a translaminal and lateral transport assay for bleaching herbicidal compounds in cotyledons.     

吡虫啉在生菜中的吸收迁移及转化行为

为了探究吡虫啉在植物中的吸收转运规律,本研究选择生菜为研究对象,将其在含有1 mg/kg吡虫啉的水培液中持续暴露120 h,利用超高效液相色谱-三重四极杆质谱检测吡虫啉及其5种代谢物在生菜不同部位动态吸收变化和转运分布规律.结果表明,吡虫啉在叶部富集程度明显高于根部,当达到吸收稳定状态时,吡虫啉在叶部富集程度约为根部的...