Uncoupling activity of some N-phenylcarbamates

In the N-phenylcarbamate family several compounds inhibit cell division and some others prevent the light-driven electron transfer in thylakoids. In this family (general formula R₁-NH-COO-R₂ where R₁ is a phenyl), 18 compounds were investigated for their possible uncoupling activity. Potent uncouplers, able to uncouple fully the oxidative phosphorylation or the photophosphorylation between 1 and 10 μM, were obtained when R₂ was 4-NO₂C₆H₄, CH₂CHCl₂ or CH₂CF₃ and R₁ was a 3,4-Cl₂C₆H₃. The -NH-group of the carbamate function is probably involved in the proton transfer through the two types of biological membranes studied here (mitochondria and thylakoids).     

Systemic fungicidal and insecticidal activities of 1- and 2-[bis (dimethylamido)phosphoryl]-3-alkyl-5-anilino-1,2,4-triazoles

The compounds referred to in the title have been investigated for fungicidal, insecticidal and acaricidal activities in laboratory and greenhouse tests. Several representatives of this class of compounds were active against powdery mildew on apple, cucumber, and barley, and against aphids and spider mites, both when applied to the leaves and when added to the nutrient solutions of test plants. Treatment of leaf halves resulted in protection of the entire leaves. A striking difference in pesticidal activity was observed between two series of isomers. Representatives of the series with the phosphoryl group in the 1-position showed much greater pesticidal activities than their corresponding isomers with the phosphoryl group in the 2-position. The optimum activity within the two homologous series (R-H, CH₃ ... C₆H₁₃) was determined: generally the lower homologues (R-H, CH₃, C₂H₅ and i-C₃H₇) showed the greatest pesticidal activity in the systemic tests. After leaf-application the influence of the length of R was less pronounced or even reversed.Samenvatting De in de titel genoemde stoffen zijn onderzocht op fungicide, insecticide en acaricide werking in laboratorium en kasproeven. Verscheidene vertegenwoordigers van dit type verbindingen waren werkzaam tegen echte meeldauw van appel, komkommer en gerst, en tegen bladluizen en spint, dit zowel na toepassing op de bladeren als na toevoeging aan de voedingsoplossingen van proefplanten. Behandeling van bladhelften resulteerde in bescherming van de gehele bladeren. Een opvallend verschil werd waargenomen tussen de werking van twee reeksen isomeren. Vertegenwoordigers van de reeks met de fosforylgroep op de 1-plaats waren veel werkzamer dan hun isomeren met de fosforylgroep op de 2-plaats. Het optimum binnen de twee homologe reeksen (R-H, CH₃ ... C₆H₁₃) werd bepaald: in het algemeen waren de lagere homologen (R-H, CH₃; C₂H₅ en i-C₃H₇) het werkzaamst in de systemische proeven. Na een preventieve bladbespuiting was de invloed van de lengte van R minder uitgesproken of zelfs omgekeerd.     

Synthesis and characterization of a group of dihydropyrimido-benzimidazole photosystem II herbicides

A group of 28 dihydropyrimido-benzimidazole analogs and derivatives was tested for herbicidal activities. The 1:1 mixture of 7-fluoro- and 8-fluorodihydropyrimido-benzimidazole had the greatest biological activity. Activity is increased by methylation of nitrogen 2. None of the active compounds was inhibitory to nonphotosynthetic tissue-culture cells in vitro. The I₅₀ of inhibition of growth of green duckweed plants and that of in vitro photosynthesis activity matched the I₅₀ of inhibition of photosystem II activity. Fluorescence analyses of photosystem II activity indicated inhibition at the same step as did many triazine, phenylurea, pyridazinone, and uracil herbicides. As the compounds showed insufficient activity on recently evolved triazine-resistant weed biotypes, their further development was terminated, despite their novel chemistry.     

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.     

Mechanism of action and selectivity of a novel herbicide,fenquinotrione

Fenquinotrione is a novel herbicide that can control a wide range of broadleaf and sedge weeds with excellent rice selectivity. We revealed that fenquinotrione potently inhibited the 4-hydroxyphenylpyruvate dioxygenase (HPPD) activity in Arabidopsis thaliana with an IC₅₀ of 44.7 nM. The docking study suggested that the 1,3-diketone moiety of fenquinotrione formed a bidentate interaction with Fe(II) at the active site. Furthermore, π–π stacking interactions occurred between the oxoquinoxaline ring and the conserved Phe409 and Phe452 rings, indicating that fenquinotrione competes with the substrate, similar to existing HPPD inhibitors. A more than 16-fold difference in the herbicidal activity of fenquinotrione in rice and the sedge, Schoenoplectus juncoides, was observed. However, fenquinotrione showed high inhibitory activity against rice HPPD. Comparative metabolism study suggested that the potent demethylating metabolism followed by glucose conjugation in rice was responsible for the selectivity of fenquinotrione.     

异香豆素噁二唑类化合物的合成及除草活性

为了寻找具有较高除草活性的异香豆素类化合物,设计合成了16个新型异香豆素噁二唑类化合物4a～4p,其结构均经核磁共振氢谱、碳谱及高分辨质谱确证。初步除草活性测定结果表明,部分目标化合物在500 mg/L下对马唐Digitaria sanguinalis L.和反枝苋Amaranthusretroflexus L.具有一定的除草活性,其中化合物4j（4-[5-（4-氯-苯基）-[1,2,4]二唑-3-基]-3-己基-6,7-二甲氧基异香豆素）的活性最好,对马唐和反枝苋的致死率分别为64%和62%。     

Novel 1,3,5-triazine derivatives with herbicidal activity

New fluoroalkyl-substituted 1,3,5-triazine derivatives were synthesized and screened for herbicidal activity using a greenhouse pot test. Surprisingly, a series of 2-alkyl-4-fluoroalkyl-6-aralkylamino-1,3,5-triazines e.g. 6-(4-bromobenzylamino)-2-methyl-4-trifluoromethyl-1,3,5-triazine was found to possess strong pre- and post-emergence herbicidal activities, although the conventional herbicidal 1,3,5-triazines generally should have a 2-substituted-4,6-diamino-1,3,5-triazine structure for herbicidal activity. Our compounds show strong Photosynthetic Electron Transport inhibitory activity (PI₅₀ c 7). Although their herbicidal effect is considered to be caused by a process similar to that for the conventional 1,3,5-triazine herbicide atrazine, they can control atrazine-resistant Chenopodium album effectively, and will thus form promising trial compounds for new triazine herbicide design.     

New analogs of pochonicine,a potent β-N-acetylglucosaminidase inhibitor from fungus Pochonia suchlasporia var. suchlasporia TAMA 87

Three novel analogs of pochonicine (1) were isolated from a solid fermentation culture of the fungal strain Pochonia suchlasporia var. suchlasporia TAMA 87, and their structures were elucidated as 7-deoxypochonicine (2), 6-deoxypochonicine (3), and 6,7-dideoxypochonicine (4). These analogs were found to possess the same stereochemistry as pochonicine. Comparison of β-N-acetylglucosaminidase (GlcNAcase) inhibitory activity between these analogs and pochonicine suggested that the C-6 hydroxy group of pochonicine was essential to its potent GlcNAcase inhibitory activity and that the C-7 hydroxy group also contributed to the activity, but to a lesser extent than the C-6 hydroxy group.     

三种化合物处理对南方根结线虫生长发育及致病能力的影响

为明确不同浓度NH4HCO3、Cu SO4·5H2O和Fe Cl3·6H2O对南方根结线虫Meloidogyne incognita 2龄幼虫活性的影响,在盆栽条件下将化合物处理后的2龄幼虫接种番茄,通过根染色和根系冰冻切片法观察2龄幼虫的发育状况和根系内巨细胞的形成,并测定了番茄根系各生理指标的变化。结果表明,50mmol/L NH4HCO3、1.4mmol/L Cu SO4·5H2O和1.4 mmol/L Fe Cl3·6H2O处理南方根结线虫后,番茄根系内2龄、3龄及4龄幼虫数量均显著小于对照;根系内丙二醛、可溶性糖和游离氨基酸的含量均显著低于对照,根系活力显著增强;经NH4HCO3处理后,根系内巨细胞形成缓慢,14 d时出现巨型细胞空洞现象。3种化合物处理对南方根结线虫生长发育的抑制作用显著,处理后的线虫对番茄植株致病力减弱,表现为NH4HCO3抑制作用最强,Cu SO4·5H2O次之,Fe Cl3·6H2O最弱。     

Pyrazole phenyl ether herbicides inhibit protoporphyrinogen oxidase

Two isomeric pairs of pyrazole phenyl ether herbicides [AH 2.429, 4-chloro-1-methyl-5-(4-nitrophenoxy)-3-(trifluoromethyl)-1H-pyrazole; AH 2.430, 4-chloro-1-methyl-3-(4-nitrophenoxy)-5-(trifluoromethyl)-1H-pyrazole; AH 2.431, 5-((4-chloro-1-methyl-5-(trifluoromethyl)-1H-pyrazol-3-yl)oxy)-2-nitrobenzoic acid; and AH 2.432, 5-((4-chloro-1-methyl-3-(trifluoromethyl)-1H-pyrazol-5-yl)oxy)-2-nitrobenzoic acid were evaluated for herbicidal activity in both intact plants and in tissue sections. Their capacity to induce accumulation of porphyrins in tissue sections and to inhibit protoporphyrinogen oxidase (Protox) in vitro were determined. In whole plant tests, the order of herbicidal activity was AH 2.430 AH 2.431 > AH 2.429 > AH 2.432. AH 2.430 consistently caused light-dependent membrane leakage in both green and far-red light grown cucumber cotyledon and barley primary leaf tissue sections after incubation for 20 hr in darkness in 0.1 mM solutions. The same treatment caused marked increases in protoporphyrin IX (PPIX) content during the 20-hr dark incubation. AH 2.429 and 2.431 were less effective and not effective in all tissues in causing herbicidal damage and PPIX accumulation. AH 2.432 was ineffective in tissue section assays. Mg-PPIX levels were not significantly affected by any of the compounds. Protochlorophyllide levels were decreased by AH 2.430 and 2.431 in barley and increased by AH 2.429, 2.431, and 2.432 in cucumber. A positive relationship was found between herbicidal activity and the amount of PPIX that was caused to accumulate by each compound. All of the compounds inhibited Protox activity. Positive correlations were found between herbicidal activity in planta over a 300-fold range and in vitro Protox inhibition and the amount of PPIX caused to accumulate in vivo. These data support the view that the pyrazole phenyl ethers exert their herbicidal activity entirely through inhibition of Protox.     

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.     

N-(7-氟-3-氧-3,4-二氢-苯并噁嗪-6-基-)乙酰胺类化合物的合成及除草活性

为了寻找高效、安全的具有除草活性的新化合物,利用2-取代乙酰氯和2H苯并噁嗪-3-酮反应合成了9个N-(7-氟-3-氧-3,4-二氢苯并噁嗪-6-基-)乙酰胺类化合物,其结构经元素分析、IR、1H NMR确证。初步除草活性测试表明:在有效剂量75 g/hm2下,化合物 5d 芽后茎叶处理对刺苋Amaranthus spinosus等4种杂草显示出90%以上的抑制率。     

Synthesis and fungitoxic activity of 5‐aryl‐1‐formyl‐4,5‐dihydro‐3‐(2‐hydroxyphenyl)‐1H‐pyrazoles and their complexes

Cyclization of 3‐aryl‐1‐(2‐hydroxyphenyl)prop‐2‐en‐1‐ones with hydrazine hydrate in refluxing formic acid afforded the title ligands, 5‐aryl‐1‐formyl‐4,5‐dihydro‐3‐(2‐hydroxyphenyl)‐1H‐pyrazoles (HL¹–HL⁴, Ar = Ph, 4‐CH₃O‐C₆H₄‐, 2‐furyl, 2‐thienyl). Reaction of HL¹–HL⁴ with the divalent metal ions, Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺, afforded novel complexes of the type [ML₂] (M = metal ion; L = deprotonated ligand) which were characterized by elemental analyses, molecular weight determinations, molar conductances, magnetic moments and electronic and infrared spectral data. The ligands behaved as tridentate, coordinating through the phenolic oxygen after deprotonation, N‐2 of the pyrazole ring and oxygen of the 1‐formyl group. The ligands and their complexes were evaluated for growth‐inhibiting activity against four phytopathogenic fungi. Macrophomina phaseoli was generally most sensitive followed by Alternaria alternata and Colletotrichum falcatum while Fusarium oxysporum was least sensitive to the tested compounds. The ligand HL¹ and its complexes showed the best activity against the fungi tested. © 2000 Society of Chemical Industry     

Genetic analysis of host–pathogen incompatibility between Lolium isolates of Pyricularia oryzae and wheat

Lolium isolate TP2 of Pyricularia oryzae, causal agent of gray leaf spot of perennial ryegrass (Lolium perenne), is virulent on perennial ryegrass, but avirulent on wheat cultivars. Genetic analysis of wheat F₂ populations revealed that the resistance of wheat cultivars Chinese Spring, Shin-chunaga, and Norin 4 to TP2 was conditioned by two genes, R1 and R2. R1 was highly effective, while R2 was less effective. The strong resistance gene R1, designated Rmg6, was mapped on chromosome 1D using microsatellite markers. For revealing genetic mechanisms of avirulence, TP2 was crossed with Triticum isolate Br48. Segregation analysis of their F₁ progenies revealed that the avirulence of TP2 on the three wheat cultivars was conditioned by two unlinked genes, one (A1) highly effective and the other (A2) less effective. These results suggest that the incompatibility between TP2 and the common wheat cultivars is conditioned by two gene pairs; the Rmg6–A1 interaction results in strong resistance, and the R2–A2 interaction results in moderate resistance.     

Diphenyl ether-chloroplast interactions

The diphenyl ethers acifluorfen (sodium-5-[2-chloro-4-(trifluoromethyl)-phenoxyl]-2-nitrobenzoate), acifluorfen-methyl (methyl-5-[2-chloro-4-(trifluoromethyl)-phenoxyl]-2-nitrobenzoate), and oxyfluorfen (2-chloro-1-[3-ethoxy-4-nitrophenoxy]-4-(trifluoromethyl)benzene have an absolute light requirement for herbicidal activity. CO₂-dependent O₂ evolution was inhibited in leaf disks obtained from 5-week-old spinach plants as a result of incubation in the light in the presence of each of the three diphenyl ethers. I₅₀'s were determined for inhibition by the diphenyl ethers of CO₂-dependent O₂ evolution in intact chloroplasts obtained from three species of varying susceptibilities (spinach, coffeeweed, and pea). Rankings obtained correlated well with relative susceptibilities and with relative effectiveness of the three compounds tested. Coupled and uncoupled photosynthetic electron transport in susceptible species were unaffected by the three compounds at concentrations in the I₅₀ range. Exposure to herbicidally inactive isomeric analogs of oxyfluorfen and acifluorfen did not affect photosynthesis in leaf disks but was effective in inhibiting photosynthesis in isolated chloroplasts. Photosynthetic abilities of intact tissue were not affected by herbicide treatment in red light. Red light was, however, as effective as white light in mediating the inhibition of photosynthesis in isolated intact chloroplasts by diphenyl ethers. The existence of two photoreceptors for diphenyl ether action, one located at the chloroplast envelope and a second outside of the chloroplast, is suggested as a possible basis for these findings.     

Quantitative structure—activity relationships of light-dependent herbicidal 4-pyridone-3-carboxanilide derivatives II. Substituent effects of anilide and pyridone moieties

The variations in the light-dependent herbicidal activity against Echinochloa oryzicola of a number of 4-pyridone-3-carboxanilides with various substituents on the anilide and pyridone rings have been examined by use of physicochemical substituent parameters and regression analysis. The effects of substituents of the anilide ring were such that the activity was related parabolically not only with the substituent hydrophobicity (π) but also with the steric bulk parameter (E_s) of the bulkier ortho substituent. The effect of substituents at the 1-position of the pyridone ring was analysed with steric(STERIMOL L and B₅) and electronic(γ₁) parameters. That of substituents at the 5-position of the pyridone ring was explained by a parabolic function of a steric (MR) parameter. Analyses of the activity of 105 analogs confirmed that our previous selection of a candidate compound in this series for field trials was indeed appropriate in terms of physicochemical substituent effects.     

Sensitivity of Rhizoctonia solani causing rice sheath blight to fluxapyroxad in China

Fluxapyroxad,3-(difluoromethyl)-1-methyl-N-(3’,4’,5’-trifluorobiphenyl-2-yl) pyrazole-4-carboxamide (C₁₈H₁₂F₅N₃O, Fig. 1), is a SDHI fungicide, which is a new active ingredient that interferes with succinate ubiquinone reductase in the electron transport chain of fungi. Between 2008 and 2010, a total of 128 isolates of Rhizoctonia solani from Anhui Province of China were characterized for the baseline sensitivity to fluxapyroxad. The isolates collected between 2008 and 2010 all showed similar sensitivity to fluxapyroxad. Baseline sensitivity was distributed as unimodal curves with an average EC₅₀ value of 0.054?±?0.014 μg ml^?1. However, EC₅₀ values of boscalid for inhibition of mycelial growth of R. solani isolates ranged from 1.89 to 2.68 μg/ml and the average (±SE) EC₅₀ value was 2.212?±?0.228 μg/ml, indicating that the R. solani isolates were less sensitive to boscalid than that of fluxapyroxad. Fluxapyroxad exhibited excellent protective and curative activity against rice sheath blight and provided 82.6–94.2 % protective or curative control efficacy. In field trials, control efficacy of fluxapyroxad at 100 g a.i/ha 15 days and 30 day after second application was 83.4–88.0 %, suggesting excellent activity against sheath blight. Control efficacy of boscalid at a dosage of 600 g a.i/ha 15 days and 30 day after second application was about 51.7–57.0 %. There was a significant difference in the efficacy between fluxapyroxad and boscalid or jinggangmycin. These results suggested that fluxapyroxad is a good alternative fungicide to jinggangmycin for the control of rice sheath blight.     

嘧啶联吡唑甲酰胺类化合物的合成及除草活性

设计合成了一系列结构新颖的嘧啶联吡唑甲酰胺类化合物5a~5o,其结构均经过1H NM R和MS分析确证。初步生物活性测试结果表明:在有效成分150 g/hm2剂量下苗后茎叶喷雾处理时,化合物(R)-N-[1-(4-氯苯基)乙基]-3-二氟甲基-1-(4,6-二甲氧基嘧啶-2-基)-1H-吡唑-4-甲酰胺(5c)、N-[1-(4-氯苯基)乙基]-1-(4,6-二甲氧基嘧啶-2-基)-N-甲基-3-三氟甲基-1H-吡唑-4-甲酰胺(5i)和N-[1-(4-氯苯基)乙基]-1-(4,6-二甲氧基嘧啶-2-基)-3-三氟甲基-1H-吡唑-4-甲酰胺(5k)对繁缕Stellaria media的抑制率高达90%以上;而同样剂量下苗前土壤喷雾处理时,化合物N-[1-(4-氯苯基)乙基]-3-二氟甲基-1-(4,6-二甲氧基嘧啶-2-基)-1H-吡唑-4-甲酰胺(5b)和5c对繁缕的抑制率达100%。该类结构化合物有望作为除草先导化合物进行开发。     

Characterization of new photosynthesis-inhibiting imidazolidine derivatives. 2. Interpretation of pre-emergence herbicidal performance from photosyghesis-inhibiting activity and soil adsorption coefficient

Ruling factors governing pre-emergence herbicidal activity were analysed for 16 photosynthesis-inhibiting 5-hydroxy-3-methyl-2–oxo-imidazolidine-1-carboxamide derivatives. Herbicidal performance was quantified by the reduction in area of experimental weed vegetation, measured by a computer-aided image analysis system. A system for fluorometric estimation of photosynthesis inhibitor concentration in aqueous solution greatly facilitated determination of the soil adsorption coefficients (K_d). Maximum herbicidal performance was found for N-sec-butyl-5-hydroxy-3-methyl-2-oxo-imidazolidine-1-carboxamide, a compound with the second lowest soil adsorptivity and average photosynthesis-inhibiting activity. A multiple regression analysis suggested that herbicidal performance of the soil-applied imidazolidine derivatives was determined by a balance between K_d and photosynthesis-inhibiting activity. In the present experimental system, however, the main influence was attributed to K_d.     

新型吡唑双酰肼类化合物的合成及除草活性

为了寻找具有较高除草活性的农药先导化合物,将吡唑环与双酰肼结构进行拼接,设计合成了13个未见报道的含吡唑环的双酰肼类目标化合物6a~6m,其结构均通过核磁共振氢谱及高分辨质谱确认。培养皿法测定结果表明:在200 mg/L下,化合物N'-(2-(2,4-二氯苯氧基)乙酰基)-3-(二氟甲基)-1-甲基-1H-吡唑-4-甲酰肼(6i)对小麦Triticum aestivum、油菜Brassicacampestris、高粱Sorghum bicolor、萝卜Raphanus sativus和黄瓜Cucumis sativus根、茎的抑制率均达80%以上。盆栽试验表明:在有效成分150 g/hm2剂量下,采用苗后茎叶喷雾处理,化合物6i对反枝苋Amaranthus retroflexus和鳢肠Eclipta prostrata的抑制率均达80%;相同剂量下采用苗前土壤喷雾处理,6i对反枝苋A. retroflexus的抑制率也达80%。