Dégradation catalytique de carbamates et amides acétyléniques. Herbicides sur bentonites homoioniques: aspects particuliers

Catalytic degradation of acetylenic herbicides amides and carbamates on dry homoionic bentonites: some particular aspects Chemical degradation of acetylenic herbicides (amides and carbamates) on dry bentonite (Fe³⁺, Mn²⁺, Cu²⁺, Zn²⁺) was studied. Zn bentonite was very active in propyzamide degradation. The influence of metal dispersion (e.g. copper) was studied. Infra-red spectroscopic studies permitted determination of the functional groups involved in the adsorption and defined qualitatively the degradation pathways previously described.     

Phytotoxicity of m-phenoxybenzamides: Inhibition of cell-free phytoene desaturation

Inhibition of carotenoid biosynthesis by herbicidal m-phenoxybenzamide derivatives has been investigated in a cell-free carotenogenic system from Aphanocapsa. Their target is the phytoenedesaturase reaction. Double-reciprocal plots of β-carotene biosynthesis (from ¹⁴C-labeled geranylgeranyl pyrophosphate) showed that 3-(2,5-dimethylphenoxy)-N-ethylbenzamide was a noncompetitive inhibitor of the phytoene-desaturase complex. The K_i value for cell-free inhibition of β-carotene formation was almost identical to the I₅₀ value of intact cells. Furthermore, the influence of certain substituents on herbicidal activity has been investigated. Inhibition increased with the length of the unbranched N-alkyl chains. In addition, substituents at the phenoxy group with higher lipophilicities showed greater inhibitory activities. The presence of a phenoxy or trifluoromethyl moiety at position 3 is essential.     

A specific and sensitive assay to quantify the herbicidal activity of chloroacetamides

Based on a recently discovered property of chloroacetamide herbicides—the inhibition of the incorporation of oleic acid into sporopollenin of Scenedesmus acutus—a rapid quantitative test was developed for chloroacetamide-type herbicidal activity. In this test, algal cells are incubated for 3 h with [¹⁴C]oleic acid, saponified and the lipids (including non-saponifiable ones) extracted and discarded. The radioactivity incorporated into the residual non-lipid fraction is determined, and inhibition of this incorporation is used as a marker of chloroacetamide-type activity. Twenty-two agrochemical compounds were screened in this assay, which was found to be very sensitive, a 50% inhibition being reached with submicromolar herbicide concentrations. It is specific to chloroacetamides and related amides, since all these herbicides tested were potent inhibitors, while other herbicides were not. Highest inhibition was shown by cafenstrole followed by butachlor, fluthiamid, metazachlor, alachlor, dimethenamid, metolachlor and mefenacet. For these herbicides (with the exception of butachlor) sensitivity in the test was positively correlated (r=0·984) with their phytotoxic effect on the alga. © 1998 SCI     

吡唑酰胺基脲类化合物的合成及除草活性

根据活性结构拼接原理,以1-甲基-3-乙基-5-吡唑甲酰肼为起始原料,设计合成了19个新吡唑酰胺基脲类衍生物,其结构均经过核磁共振氢谱、红外光谱、质谱和元素分析确证。生物活性测试结果表明:大部分化合物对双子叶杂草苘麻Abutilon theophrasti、反枝苋Amaranthus retroflexus以及凹头苋A.ascedense显示出较好的除草活性及选择性,如在2 250 g/hm2的剂量下,3i在苗后和苗前处理时,对苘麻和反枝苋的抑制率都达到了100%。复筛的结果表明,在375 g/hm2下,3i对双子叶杂草表现出中等除草活性。     

Effect of different photosystem II inhibitors on chloroplasts isolated from species either susceptible or resistant toward s-triazine herbicides

In chloroplasts isolated from susceptible and atrazine-resistant Amaranthus retroflexus, the inhibition of photosynthetic electron transport by various classes of herbicides has been investigated. Resistance of mutant Amaranthus is not restricted to s-triazines but also extends to uracils, 1,2,4-triazine-5-ones, and ureas. For 1,2,4-triazin-5-ones and chloroplasts of both biotypes, a correlation between inhibition of photosynthetic electron transport and the partition coefficient could be established. In the case of phenolic herbicides only modestly decreased or even higher sensitivity of chloroplasts from the resistant biotype as compared to the susceptible one could be observed. These results are confirmed by binding of radioactively labeled herbicides to chloroplasts of both plants. Specific binding of atrazine or metribuzin to resistant chloroplasts is completely abolished, and that of diuron or phenisopham diminished as compared to susceptible chloroplasts. In contrast, binding of phenolic herbicides generally is enhanced in resistant chloroplasts. Photoaffinity labeling of thylakoids from both biotypes by 2-azido-4-nitro-6-[2′,3′-³H]isobutylphenol yields almost identical labeling patterns. These results are consistent with a recently proposed model (W. Oettmeier, K. Masson, and U. Johanningmeier, Biochim. Biophys. Acta679, 376 (1982) of two different herbicide binding proteins at the reducing side of photosystem II: a 32- to 34-kdalton protein responsible for binding of triazines, triazinones, ureas, and related herbicides and a photosystem II reaction center protein for binding of phenolic herbicides.     

Effects of herbicides and herbicide analogs on [14C]leucine incorporation by suspension-cultured Solanum nigrum cells

Assays of [¹⁴C]leucine incorporation were used to measure effects of herbicides on suspensioncultured heterotrophic Solanum nigrum cells. Most herbicidal vs. nonherbicidal chemicals in a set of 47 compounds could be distinguished from each other based on their extent of inhibition of leucine incorporation by S. nigrum cells. Herbicides which failed to inhibit leucine incorporation were photosynthetic inhibitors. Both phytotoxic and nonphytotoxic thiocarbamate analogs (as determined by whole-plant studies) tended to inhibit leucine incorporation. It was concluded that the leucine incorporation screen could detect a majority of compounds tested which are herbicidal, and that it may also be useful to detect compounds which have cellular toxicity which is not observed in the whole plant.     

Influence of the herbicides hexazinone and chlorsulfuron on the metabolism of isolated soybean leaf cells

The effects of the herbicides hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] and chlorsulfuron (2-chloro-N-[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)aminocarbonyl]benzenesulfonamide) on the metabolism of enzymatically isolated leaf cells from soybean [Glycine max (L.) Merr., cv. ‘Essex’] were examined. Photosynthesis, protein, ribonucleic acid (RNA), and lipid syntheses were assayed by the incorporation of specific radioactive substrates into the isolated soybean leaf cells. These specific substrates were NaH¹⁴CO₃, [¹⁴C]leucine, [¹⁴C]uracil, and [¹⁴C]acetate, respectively. Time-course and concentration studies included incubation periods of 30, 60, and 120 min and concentrations of 0.1, 1, 10, and 100 μM of both herbicides. Photosynthesis was the most sensitive and first metabolic process inhibited by hexazinone. RNA and lipid syntheses were also inhibited significantly by hexazinone whereas the effect of this herbicide on protein synthesis was less. The most sensitive and first metabolic process inhibited by chlorsulfuron was lipid synthesis. Photosynthesis, RNA, and protein syntheses were affected significantly only by the highest concentration of this herbicide and longest exposure. Although these two herbicides may exert their herbicidal action by affecting other plant metabolic processes not examined in this study, hexazinone appears to be a strong photosynthetic inhibitor, while the herbicidal action of chlorsulfuron appeared to be related to its effects on lipid synthesis.     

Characterization of herbicidal injury by acifluorfen-methyl in excised cucumber (Cucumis sativus L.) cotyledons

Initial signs of herbicidal injury by several diphenyl ether herbicides were monitored by following the efflux of ⁸⁶Rb⁺ from treated cucumber (Cucumis sativis L.) cotyledons after exposure to light (600 μE m^?2 sec^?1; measured as PAR, i.e., photosynthetically active radiation between 400 and 700 nm). This very sensitive, rapid, and quantitative bioassay proved quite useful in (a) a structure-activity correlations study of the diphenyl ether compounds investigated and (b) an examination of herbicidal characteristics. The following diphenyl ether herbicides were analyzed: acifluorfen, sodium 5-[2-chloro-4-(trifluormethyl)phenoxy]-2-nitrobenzoate; acifluorfen-methyl (MC-10108), methyl 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoate; bifenox, methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate; nitrofen, 2,4-dichlorophenyl p-nitrophenyl ether; nitrofluorfen, 2-chloro-1-(4-nitrophenoxy)-4-(trifluoromethyl)benzene; oxyfluorfen, 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene; MC-7783, potassium 5-(2,4-dichlorophenoxy)-2-nitrobenzoate; and MC-10982, ethyl 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoate. Of the compounds investigated, acifluorfen-methyl (AFM) had the greatest degree of herbicidal activity. Cucumber cotyledons placed in high light (600 μE m^?2 sec^?1; PAR) with 10 nM AFM showed a significant increase in the efflux of ⁸⁶Rb⁺ within 2 to 4 hr. Light was required for herbicidal activity by AFM, and when treated cotyledons were returned to darkness, no further damage to the tissue occurred. By decreasing the quantity of light, the effect of the compound was delayed, although the magnitudes of the responses at the different intensities (600, 300, 150, and 75 μE m^?2 sec^?1; PAR) were nearly equal. By increasing the length of time of dark pretreatment with 1 μM AFM, ⁸⁶Rb⁺ efflux could be detected as early as 10 to 15 min after exposure to light (600 μE m^?2 sec^?1; PAR). Following light activation of AFM there was a simultaneous efflux of ⁸⁶Rb⁺, ³⁶Cl^?, ⁴⁵Ca²⁺, 3-O-methyl-[¹⁴C]glucose, and [¹⁴C]methylamine⁺. These data suggest the initial response to the herbicidal activity of AFM is expressed as a general increase in membrane permeability.     

Jack bean urease inhibition by substituted ureas

The increased use of urea fertilizer and substituted ureas herbicides, the implication of soil urease in the effectiveness of urea applied as fertilizer, makes necessary to investigate their relationship.All herbicides investigated, fenuron, monuron, diuron, linuron, siduron and neburon are urease inhibitors. The inhibition constant value depends on molecular groups on the urea skeleton. There is a linear relationship between the Hammett sigma values and log Ki for fenuron, monuron and diuron.The presence of a large hydrophobic group and of one or two chlorine—an electron withdrawing group—on the phenyl ring of the herbicides molecule influences the Ki value.The hypothesis is proposed that the enzyme molecule reacts with inhibitors by means of the oxygen atom of the carboxyl group in the substituted ureas.     

吡啶衍生物研究(IX):N-(1-甲氧羰基)乙基-N-[5-(2-氯吡啶-4-基)-1,3,4-噻二唑-2-基]酰胺的合成及除草活性

为了进一步研究前期发现的除草先导化合物2-仲丁氨基-5-(2-氯吡啶-4-基)-1，3，4-噻二唑(BCPT)的结构-活性关系并提高其除草活性，设计并合成了一系列N-(1-甲氧羰基)乙基-N-[5-(2-氯吡啶-4-基)-1，3，4-噻二唑-2-基]酰胺类化合物。其苗后除草活性测定结果表明，所有化合物的活性都远低于BCPT本身。说明BCPT可能具有与传统酰胺类除草剂不同的作用机制。     

An evaluation of the herbicidal and plant growth regulatory activity of a novel class of carbohydrate-derived 6,8-dioxabicyclo[3.2.1]octanes

Thirty-five carbohydrate-derived dioxabicyclo[3.2.l]octane derivatives have been tested for herbicidal and plant growth regulatory (PGR) activity in an Arabidopsis thaliana assay. Nine of these were herbicidal at concentrations of ? 16 μg ml^?1 in the growth medium. Three compounds, viz, 1,6-anhydro-3-deoxy-4-O-(2,6-dichlorobenzyl)-2-O-methyl-β-D-ribo-hexopyranose(I), its 4-O-benzyl analogue (II), and l,6-anhydro-2-azido-4-O-benzyl-2,3-dideoxy-β-D-ribo-hexopyranose (III) were very active herbicides, killing plants by the rosette stage at 1 μg ml^?1 or less. At lower rates, the herbicides acted as growth regulators, reducing growth rates of shoots and roots as well as flowering and seed-pod development. A further 14 compounds exerted PGR effects only, while 12 compounds were virtually inactive at 16 μg ml^?1, the highest rate tested. The ability of the active compounds to reduce seed viability on mature plants at sublethal concentrations was demonstrated in four cases.     

Chemistry of sulfonylurea herbicides

The discovery of the sulfonylurea class of herbicides is one of the most dramatic breakthroughs in herbicide research in several decades. Sulfonylureas possess unprecedented levels of herbicidal activity–as low as 1 g ha^?1–very low mammalian toxicity, and very desirable environmental properties. This review will discuss the structure-activity relationships of sulfonylureas, their physical and chemical properties, and their methods of synthesis.     

Localizing the action of two thiadiazolyl herbicidal derivatives

Enzymatically isolated leaf cells from navy beans (Phaseolus vulgaris L., cv. “Tuscola”) were used to study the effect of buthidazole (3-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-4-hydroxy-1-methyl-2-imidazolidinone) and tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea) on photosynthesis, protein, ribonucleic acid (RNA), and lipid synthesis. The incorporation of NaH¹⁴CO₃, [¹⁴C]leucine, [¹⁴C]uracil, and [¹⁴C]acetic acid as substrates for the respective metabolic process was measured. Time-course and concentration studies included incubation periods of 30, 60, and 120 min and concentrations of 0.1, 1, 10, and 100 μM of both herbicides. Photosynthesis was very sensitive to both buthidazole and tebuthiuron and was inhibited in 30 min by 0.1 μM concentrations. RNA and lipid syntheses were inhibited 50 and 87%, respectively, by buthidazole and 42 and 64%, respectively, by tebuthiuron after 120 min at 100 μM concentration. Protein synthesis was not affected by any herbicide at any concentration or any exposure time period. The inhibitory effects of buthidazole and tebuthiuron on RNA and lipid syntheses may be involved in the ultimate herbicidal action of these herbicidal chemicals.     

Synthesis and herbicidal potential of substituted aurones

BACKGROUND: With the objective of exploring the herbicidal activity of substituted aurones, a series of 4,6‐disubstituted and 4,5,6‐trisubstituted aurones were synthesised, and their herbicidal activities against Brassica campestris L. and Echinochloa crusgalli (L.) Beauv. were evaluated in laboratory bioassays. Effects of some of the compounds were evaluated on seed germination. The most active compounds in the laboratory were evaluated in the greenhouse. RESULTS: The compounds were characterised by ¹H NMR, ¹³C NMR and HRMS; some of them were further identified by IR. A (Z)‐configuration was assigned to the aurones, based on spectroscopic and crystallographic data. Bioassay results of root growth showed that the aurones had a moderate herbicidal activity against the dicotyledonous plant Brassica campestris. (Z)‐2‐Phenylmethylene‐4,6‐dimethoxy‐3(2H)‐benzofuranone(6o) was the most active compound, with 81.3 and 88.5% inhibition at 10 and 100 µg ml^?1 respectively, equal to the activity of mesotrione. Some of the aurones possessed some inhibition of germination on several plant species. For glasshouse tests, the substituted aurones had lower herbicidal activity than metolachlor and mesotrione. CONCLUSION: It is possible that aurone derivatives, which possess structures different from those of the commercial herbicides, may become novel lead compounds for the development of herbicides against dicotyledonous weeds with further structure modification. Copyright © 2012 Society of Chemical Industry     

含肟醚并取代异 NFDA1唑环的氨基甲酸酯类化合物的合成及生物活性

为寻找具有优异生物活性的氨基甲酸酯类化合物,根据活性亚结构拼接原理,将取代异 NFDA1 唑和肟醚基团引入多菌灵结构中,以取代苯甲醛 (1) 和2-氯苄胺(3) 为起始原料,经多步反应设计合成了10个未见文献报道的含肟醚并取代异 NFDA1 唑的氨基甲酸酯类化合物,其结构经 1H NMR 和 MS 确证。初步生物活性测定结果表明,部分目标化合物不仅具有一定的杀菌活性,同时还具有较好的除草活性。其中,活体盆栽试验结果表明,化合物11b对黄瓜霜霉病Pseudoperonospora cubensis 的相对防效为90%,对黄瓜白粉病Sphaerotheca fuliginea 的相对防效达95%,低于对照药剂多菌灵;除草活性皿测法表明,化合物11c和11j 200 mg/L下对靶标作物的根、茎抑制率均达80%以上,与对照药剂异丙酯草醚活性相当。盆栽法表明,150 g/hm2下,化合物11c和11j对繁缕Stellaria media苗前和苗后的抑制率均在70%以上,低于异丙酯草醚。此类化合物的构效关系有待进一步研究。     

Pyrimidinyl-substituted amides and thioureas: syntheses, crystal structure and herbicidal activities

BACKGROUND: The high herbicidal activities of [1,2,4]triazolo[1,5-c]pyrimidine and 2H-1,2,4-thiadiazolo[2,3-a]pyrimidine derivatives suggested the development of new fused heterocyclic compounds for application as herbicides. RESULTS: Three series of pyrimidinyl-substituted thioureas (4) and amides (5, 6) were synthesized, and the typical crystal structure of a 2H-1,2,4-thiadiazolo[2,3-a]pyrimidine derivative (5a) was determined by X-ray diffraction. All the compounds were tested for herbicidal activity against selected weeds. CONCLUSION: The series of fused heterocyclic amides 5a to 5d exhibited high herbicidal activities both against monocotyledonous weeds (Echinochloa crus-galli L., Sorghum bicolor (L.) M?nch., Digitaria sanguinalis (L.) Scop) and against dicotyledonous weeds (Amaranthus retroflexus L. and Brassica campestris L.) in pre-emergence treatments. In particular, compound 5b at low concentration still showed high inhibitory activity against A. retroflexus in pre-emergence treatment. Different substituents at the meta positions of the pyrimidine ring were found to affect the herbicidal activity.     

Toxicological and metabolic parameters of the teleost fish (Leporinus obtusidens) in response to commercial herbicides containing clomazone and propanil

Pesticides, such as herbicides can affect the metabolic and toxicological parameters on fish. For this reason, an experiment was carried out with the objective of to evaluate the effects of commercial formulations of clomazone and propanil herbicides on acetylcholinesterase (AChE), thiobarbituric acid-reactive substances (TBARS), catalase (CAT) and metabolic parameters in teleost fish (Leporinus obtusidens). Fish were exposed during 90 days to field measured concentration of the herbicides clomazone and propanil (376 and 1644 μg/L, respectively) on rice paddy water. Specific AChE activity in the brain and muscle decreased and TBARS levels decreased in brain, muscle and liver tissues. Liver catalase decreased after exposure to both herbicides. Metabolic parameters in the liver and white muscle showed different changes after exposure to both herbicides. In summary, the results showed that clomazone and propanil affects toxicological and metabolic parameters of piavas. These results suggest that environmentally relevant herbicides concentrations are toxic to Leporinus obtusidens.     

Herbicidal phenylalkylureas as possible mutagens: II. Chemical basis of mutagenic activity

The herbicide monuron (N-(4-chlorophenyl)-N′, N′-dimethylurea)—a recognized carcinogen—and some of its congeners have been found also to induce back mutations in Salmonella typhimurium (Ames test), as well as micronuclei in mouse bone marrow cells and an inhibition of testicular DNA synthesis (DSI test) in mice. As both the Ames test and the DSI test correlate well with chemical carcinogenicity, urea herbicides in general might be suspected of carcinogenic activity. In order to investigate the potential carcinogenic mode of action of these substances we looked for possible activation mechanisms. The reaction sequence N-oxidation-esterification-carbonium ion formation seemed the only one able to fit the observed structure-activity relationships. Chemical synthesis of the proposed N-acetoxy compounds provided the means for testing this hypothesis. Only the N-acetoxy-, but neither the N-hydroxy- nor the unchanged parent ureas, exhibited a direct alkylating action as measured by the NBP-assay. The DSI reactivity pattern of several positional isomers could be shown to coincide with the theoretical predictions, as did the stability of the chloroisomers in aqueous solution at pH 7. Furthermore the N-acetoxy derivatives could be demonstrated to behave in the Ames test as directly acting mutagens, while the activity of the parent compounds is dependent on the metabolic activation by an S-9-liver fraction. The enhancing action of Acetyl-CoA on the S-9 mediated mutagenicity of these ureas can then be regarded as the final proof for the proposed reaction sequence.     

1,3,4(2H)-isoquinolinetrione herbicides: Novel redox mediators of photosystem I

A series of 1,3,4(2H)-isoquinolinetriones have been found to be fast-acting post-emergence herbicides, producing symptoms of desiccation. These redox-active compounds are very potent stimulators of the light-dependent consumption of oxygen at photosystem I in isolated chloroplasts. Pulse radiolysis studies on 2-ethyl-1,3,4(2H)-isoquinolinetrione have shown it to have free-radical properties which could enhance the generation of superoxide radicals in plants. Electrochemical studies further support a redox mediator mode of action for the series. The compounds were found to be unstable towards hydrolysis, and this was considered to be a major factor limiting the overall herbicidal effects. Other parameters, related to uptake and/or translocation, which may limit the full expression of the herbicidal activity of certain compounds, are discussed.     

Quantitative structure-activity relationships of herbicidal N′-substituted phenyl-N-methoxy-N-methylureas

Relationships between three types of herbicidal activity of N′-substituted phenyl-N-methoxy-N-methylureas and substitution at the benzene ring were analyzed by the Hansch-Fujita method. First, the Hill inhibitory activity was correlated with electronic (σ) as well as hydrophobic (π) substituent constants. The existence of an optimum value of hydrophobicity for substituents was suggested to reach the target site of action. Second, bliaching activity observed for the 3-substituted but not for 4-substituted compounds was correlated with π, σ, and steric substituent constant, E_s. Third, the postemergent herbicidal activity was shown to correlate linearly with the Hill inhibitory activity, pI₅₀, and hydrophobic parameter, π.