METABOLISM OF MONURON IN EXCISED LEAVES OF CORN AND BEAN PLANTS*

Summary. The metabolism of monuron in excised leaves of bean (Phaseolus vulgaris L., var. Black Valentine) and corn (Zea mays L., var. Batam Cross) were studied with carbonyl-¹⁴C-labelled monuron. The metabolic conversions of monuron in both plant species were exponential and followed first order reaction kinetics. The metabolism of monuron can be divided into two major pathways: demethylation and hydroxylation. At a monuron concentration of 16 ppm the hydroxylation was dominant in the bean leaves. As the concentration of monuron was increased the participation of the hydroxylation pathway became less probably due to the inhibition of enzymes involved by monuron. The demethylation pathway was not affected by higher monuron concentration. In the corn leaf, however, sequential demethylation was always the major pathway of monuron transformation and there was no inhibitory effect observed on either pathways as the concentration of monuron increased. The following radioactive metabolites were found in the alcohol extract of bean and com leaves receiving carbonyl-¹⁴C-labelled monuron: N′-(4-chlorophenyl)-N-methylurea, p-chlorophenylurea, two polypeptide complexes of monuron, one polypeptide complex of N′-(4-chlorophenyl)-N-methylurea and β-D-glucosides of N-(2-hydroxy-4-chlorophenyl) urea, N′-(2-hydroxy-4-chlorophenyl) N-methylurea, and N′-(2-hydroxy-4-chlorophenyl)-N,N-dimethylurea. In addition, one minor radioactive peak was found only in the alcohol extract of corn leaves, which yielded four unidentified radioactive metabolites after acid or enzyme hydrolysis with β-glucosidase. Métabolisme du monuron dans des feuilles excisés de maïs et de haricot     

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。     

山蒟中脂肪链酰胺类化合物的分离及杀虫活性

采用提取、萃取及柱层析等方法,从山蒟Piper hancei Maxim甲醇提取物的石油醚和氯仿萃取相中分离到6个脂肪链酰胺类化合物,通过核磁共振、质谱并结合相关文献比对,其结构被分别鉴定为已知化合物chingchengenamide A( C1 )、N-异丁基-反-2-反-4-癸二烯酰胺( C2 )、假荜拨酰胺A( C3 )、荜茇宁( C4 )、N-p-香豆酰酪胺( C5 )和N-反式-阿魏酰酪胺( C6 ),其中 C1 为首次从山蒟中获得。利用幼虫浸液法测试了各化合物对白纹伊蚊Aedes albopictus和致倦库蚊Culex pipiens quinquefasciatus幼虫的12 h杀虫活性。结果表明:在20 mg/L下,化合物 C1 对白纹伊蚊的杀虫活性较高,其校正死亡率为100%,LC₅₀值为5.37 mg/L;化合物 C1 、 C2 、 C3 和 C4 对致倦库蚊的杀虫活性较高,20 mg/L下的校正死亡率分别为100%、88.5%、100%和100%,LC₅₀值分别为1.03、9.68、3.08和2.87 mg/L。     

Conversion of [14C]buturon in soil and leaching water under outdoor conditions

[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.     

Biological Activity of Two Stereoisomers of the N-Thienyl Chloroacetamide Herbicide Dimethenamid

Due to the presence of an asymmetrically substituted C atom, dimethenamid [2-chloro-N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)acetamide], a recently introduced N-thienyl chloroacetamide herbicide, exists as two stereoisomers (S and R) having differing herbicidal activities as demonstrated with a selection of weeds and Lemna minor. The activity of the two isomers was investigated in greater detail with the green alga Scenedesmus acutus and compared to that of alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide]. As with alachlor, the S isomer (5 μM ) strongly inhibited algal growth and fatty acid desaturation while the R isomer had no effect. In short-term experiments (up to 5·5 h), the S isomer and alachlor (100 μM ) inhibited [¹⁴C]acetate uptake and its incorporation into fatty acids in the same manner, while the R isomer did not. Incorporation of [¹⁴C]acetate into a non-lipid fraction of the algae was strongly inhibited by alachlor and the S isomer (100 μM ) and only slightly by the R isomer. A 50% inhibition of incorporation of [¹⁴C]oleic acid into the same non-lipid fraction was attained with less than 10^-7 M of the S isomer while 10^-5 M of the R form of dimethenamid achieved only a 40% inhibition. The same stereospecificity of the compound on growth, fatty acid desaturation, acetate uptake and oleic acid incorporation provides strong evidence that dimethenamid may act upon a primary, specific target in lipid metabolism. Furthermore, the comparable biological activities of dimethenamid and alachlor indicate that this target is common to both N-phenyl and N-thienyl chloroacetamide herbicides. © 1997 SCI.     

Distribution and degradation of dinitroaniline herbicides in an aquatic ecosystem

The accumulation potential of six, structurally related, dinitroaniline herbicides was investigated in an aquatic ecosystem. The herbicides investigated were trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine], dinitramine [N³,N³-diethyl-2,4-dinitro-6-(trifluoromethyl)-m-phenylenediamine], chlornidine [N,N-bis(2-chloroethyl)-2,6-dinitro-p-toluidine], fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline], and butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine]. The herbicide (0.1 mg) plus 1 μCi of ¹⁴C-labeled herbicide was adsorbed on 100 g of soil (1 ppm), added to individual aquariums, and flooded with 4 liters of water. Algae, snails, and daphnia were added, and ¹⁴C in water was monitored for 30 days. Fish were added on Day 30, and all components were harvested 3 days later. Bioaccumulation ratios (concentration in organism/concentration in water) for fish depended on the amount of their exposure to sunlight: Aquariums held in the dark had higher ratios for fish (235–755) than did those exposed to sunlight (32–83). Bioaccumulation ratios in the dark for fish based on ¹⁴C from bound soil residues of butralin and profluralin were 76 and 119, respectively. Direct repeated applications of profluralin (without soil) at 4-day intervals resulted in a rapid increase, then a decrease in bioaccumulation ratios for Gambusia, but a continuous increase for catfish.     

Growth regulator inhibition of tobacco callus growth

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.     

Transformations of 4-chloro-o-toluidine in soil: Generation of coupling products by one-electron oxidation

Four coupling products formed by one-electron oxidation of 4-chloro-o-toluidine were isolated from soil samples after 90 days of incubation with [¹⁴C]chlordimeform (200 mg/kg). The metabolic compounds were identified as 4,4′-dichloro-2,2′-dimethyl-azobenzene, 4-chloro-6-nitro-o-toluidine, N-(4-chloro-o-tolyl)-2-methyl-p-benzoquin-one monoimine and 2-(4-chloro-o-toluidino)-N-(4-chloro-o-tolyl)-6-methyl-p-benzo-quinone monoimine, respectively. Mechanisms of formation and possible significance of these substances as indicators for metabolic pathways to mineralisation of aniline derivatives are discussed. The chlordimeform soil concentrations (70–100 mg/kg) necessary for the formation of the azobenzene and the benzoquinone monoimines are at least 10 times higher than those occurring after actual field application.     

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%。     

Interaction of formamidines with octopamine-, dopamine-and 5-hydroxytryptamine-sensitive adenylate cyclase in the nerve cord of Periplaneta americana

The interaction of chlordimeform, N¹-demethylchlordimeform [N²-(4-chloro-o-tolyl)-N¹-methylformamidine], BTS-27271 [N¹-methyl-N²-(2,4-xylyl)formamidine, the 2,4-xylyl analogue of N¹-demethylformamidine], and amitraz with octopamine-, dopamine-, and 5-hydroxytryptamine-mediated enhancement of cyclic-AMP production was investigated in nerve cord homogenates of the American cockroach Periplaneta americana. N¹-Demethylchlordimeform, BTS-27271 and amitraz simulated the actions of the monoamines in enhancing cyclic-AMP production, whereas chlordimeform showed no such agonism. Additivity studies indicated that these formamidine derivatives were interacting with dopamine- and 5-hydroxytryptamine-sensitive sites, in addition to their known interaction with octopamine-sensitive adenylate cyclase. N¹-Demethylchlordimeform (Ki= 0.2μM) and amitraz (Ki=0.5μM) inhibited the dopamine-mediated response, but only N¹-demethylchlordimeform (Ki=2μM) effected appreciable inhibition of the octopamine-response. Pharmacological characterisation of the formamidineinduced elevation of cyclic-AMP production indicated that the agonistic effects of formamidines are expressed primarily through the octopamine-sensitive adenylate cyclase, rather than the dopamine- or 5-hydroxytryptamine-sensitive sites. The results are discussed in the light of the proposal that the behavioural changes, associated with formamidine poisoning, reflect the cumulative effects of octopamine-agonism, and antagonism of the dopamine- and 5-hydroxytryptaminemediated processes.     

Structural Effects of N-Arylcarbamoylpyrazolines on Calcium Uptake in Rat Brain Synaptosomes

N-Arylcarbamoylpyrazolines with various substituents at the para position of the carbamoyl benzene ring inhibited ATP-dependent Ca²⁺-uptake in synaptosomes prepared from the rat brain. The activity of these compounds was evaluated as log(1/I₅₀), the reciprocal logarithm of half inhibitory concentration, I₅₀ (m ), from the concentration–response curve for the inhibition of Ca²⁺-uptake. Among the compounds tested, methyl 3-(4-chlorophenyl)-4-methyl-1-[N-(4-trifluoromethylphenyl)carbamoyl]-2-pyrazoline-4-carboxylate was the most potent, the I₅₀ value of which as 9·12×10⁻⁷ m . Variations in the activity in terms of log(1/I₅₀) were quantitatively analysed using a substituent parameter, showing that the higher the electron-withdrawing effect of the substituent, the higher was the activity. The substituent effects were similar to those on insecticidal activity against the Americal cockroach. The higher the inhibitory activity against Ca²⁺ uptake, the higher seemed to be the insecticidal activity. Methyl(4S) - 3 - (4 - chlorophenyl) - 4 - methyl - 1 - [N - (4 - chlorophenyl)carbamoyl] - 2 - pyrazoline -4-carboxylate had higher inhibitory activity against Ca²⁺-uptake and higher in-secticidal activity than the R-isomer, but the difference was greater in theCa²⁺-uptake system.     

Comparative effects of three isoxazole-urea herbicidal derivatives on the metabolism of enzymatically isolated soybean leaf cells*

The effects of the herbicide isouron and of its plant degradation products designated as metabolite l {N-[5-(1,1-dimethylethyl)-3-isoxazolyl]-N-methylurea} and metabolite 2 {N-[5-(1,1-dimethylethyl)-3-isoxazolyl]-urea} on the metabolism of enzymatically isolated leaf cells of soybean [Glycine max (L.) Merr., cv. Essex] were compared under laboratory conditions. Photosynthesis, protein synthesis, ribonucleic acid synthesis, and lipid synthesis were assayed by the incorporation of NaH¹⁴CO₃, [¹⁴C]-leucine, [¹⁴C]-uracil, and [¹⁴C]-acetate, respectively, into the isolated cells. 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 the three herbicides. The urea derivative of isouron (metabolite 2) was the least active of the three compounds. The activity of the mono-methylated derivative of isouron (metabolite 1) was comparable to that of isouron and the sensitivity of the four processes to both chemicals decreased in the order: photosynthesis > ribonucleic acid synthesis > lipid synthesis > protein synthesis. The concentration of isouron that caused a 50% inhibition of photosynthesis of the isolated soybean leaf cells was calculated at 0.51 μM. The effects of isouron and metabolite 1 on photosynthesis, lipid and RNA synthesis appeared to be independent of incubation lime as maximal inhibition occurred within 30 min. Inhibition of protein synthesis by both chemicals was time-dependent, increasing in magnitude with concomitant increases in incubation time.     

The antifungal activity of some sulphonyl derivatives of isoxazole,pyrazole, thiazole and thiophene

Fifty-three heterocyclic sulphonyl derivatives including eight sulphonamides, three sulphonyl azides, nine sulphonohydrazides and twenty sulphonohydrazones of substituted thiophenes, and a smaller range of analogous isoxazoles pryazoles and thiazoles, were tested as potential fungicides in a simple screening procedure against Mucor mucedo, Septoria nodorum, Trichoderma viride, Chaetomium globosum and Aspergillus niger. Several thiophene-2-sulphonyl based compounds exhibited a high level of antifungal activity at 100 mg litre^?1 against the five test species, especially the mono-halogen-substituted sulphonamides and sulphonohydrazines, in which a single chlorine or bromine atom was substituted in the para position of an attached phenyl ring. The most active compound, against all five species of fungus was N-(4-chlorophenyl)-N-(trichloromethylthio) thiophene-2-sulphonamide which had average MIC₅₀ and MIC₁₀₀ values of 86 and 180 μmol respectively. (MIC₅₀ and MIC₁₀₀ values are, respectively, the concentrations required to inhibit fungal growth by 50% and to inhibit it totally.) In general, the isoxazole analogues of the thiophene-2-sulphonyl compounds exhibited a much lower fungitoxic activity, whilst the pyrazole and thiazole based compounds had little or no activity. Compared with the other results, the considerable activity shown by 4-[2′-(3,4-dichlorobenzylidene)hydrazinosulphonyl]thiophene-2-carboxylic acid was unexpected.     

Enhanced Mineralization of [14C]Atrazine in Kochia scoparia Rhizospheric Soil from a Pesticide-Contaminated Site

Mineralization of atrazine (6-chloro-N²-ethyl-N⁴-isopropyl-1,3,5- triazine-2,4-diamine) in soil treated with a mixture of atrazine and metolachlor (2-chloro-6′-ethyl-N-(2-methoxy-1-methylethyl)acet-o-toluidide at concentrations typical of point-source contamination (50 μg g⁻¹ each) was significantly greater (P<0·001) in rhizospheric soil from Kochia scoparia (L.) Roth., a herbicide-resistant plant, than in non-vegetated and control soils. Soils were collected from an agrochemical dealership contaminated with several herbicides, including atra-zine, metolachlor, trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine and pendimethalin (N-(1-ethylpropyl)-2,6-dinitro-3,4-xylidene), at concentrations well exceeding the field application rates. Mineralization rates of ring-labeled atrazine in both rhizospheric and non-vegetated soils were quite high (>47% of the initial ¹⁴C applied after 36 days) compared to literature values. These results suggest that plants such as Kochia might be managed at pesticide-contaminated sites to help facilitate microbial degradation of wastes such as atrazine in soil.     

Degradation of the herbicide flamprop-isopropyl in soil under laboratory conditions

The degradation of the wild-oat herbicide flamprop-isopropyl, [isopropyl (±)-N-benzoyl-N-(3-chloro-4-fluorophenyl)alaninate], in four soils has been examined under laboratory conditions with sampling times of up to 45 weeks after treatment. The major degradation product of [¹⁴C]flamprop-isopropyl in all soils at up to 10 weeks after treatment was the carboxylic acid (±)-N-benzoyl-N-(3-chloro-4-fluorophenyl)alanine. This compound in turn underwent degradation by loss of the benzoyl group and the propionic acid moiety, with evolution of [¹⁴C]carbon dioxide to form 3-chloro-4-fluoroaniline (CFA). The CFA was formed slowly in soil and occurred mainly as a bound form. There was evidence to show that the CFA was subsequently converted into other polar products. The time for depletion of 50% of the applied herbicide was approximately 10 weeks in sandy loam and medium loam soils, 11 weeks in a clay loam soil and 23 weeks in a peat soil.     

Mechanism of hydantoin ring opening in iprodione in aqueous media

The hydrolysis kinetics of iprodione in alkaline solutions of pH 8.3 to 12 at 25°C have been determined by ultraviolet spectrophotometry. Under these conditions, iprodione leads quantitatively and irreversibly to N-(3,5-dichloroanilinocarbonyl)-N-(isopropylaminocarbonyl)glycine. The reaction is not subject to a general basic catalysis and the rate law takes the form K_obs = K_OH- [OH^?1]. The activation entropy of -77 J mol^?1deg^?1, the value of the kinetic solvent isotope effect k_OH?/k_OD? of 0.79 and the value of 0.60 for the Hammett parameter σ, obtained for the hydrolysis of a series of 3-aryl-N-isopropyl-2,4-dioxoimidazolidine-1-carboxamides are all in agreement with the rate-determining attack by the hydroxyl ion on the carbonyl in the 4-position of the hydantoin ring of the fungicide.     

Degradation of the herbicide flamprop-methyl in soil

The degradation of the wild oat herbicide flamprop-methyl [methyl DL -N-benzoyl-N-(3-chloro-4-fluorophenyl)alaninate] in four soils has been studied under laboratory conditions using ¹⁴C-1abelled samples. The flamprop-methyl underwent degradation more rapidly than its analogue flamprop-isopropyl. However, similar degradation products were formed, namely the corresponding carboxylic acid and 3-chloro-4-fluoroaniline. The latter compound occurred mainly as ‘bound’ forms although evidence was obtained of limited ring-opening to give [¹⁴C]carbon dioxide. The time for depletion of 50% of the applied herbicide was approximately 1-2 weeks in sandy loam, clay and medium loam soils and 2-3 weeks in a peat soil.     

1(R)-(2,6-cis-dimethylmorpholino)- 3(S)-(p-tert-butylphenyl)cyclopentane: A representative of a novel,potent class of bio-rationally designed fungicides

Inhibition of the Δ⁸-Δ⁷ sterol isomerase in the ergosterol biosynthesis pathway is known to lead to fungistatic or even fungicidal effects. Our approach to the rational design of new putative inhibitors of the enzyme was based on the assumed mechanism of the enzymic transformation and in particular on the structure of the unstable carbocationic intermediate, i.e. the ‘transition-state-analogue’ principle. The synthesis and the biological properties of 1(R)-(2,6-cis- dimethylmorpholino)-3(S)-(p-tert-butylphenyl)cyclopentane, a representative of a novel, potent class of rationally designed fungicides, as well as the synthesis and biological activities of several other related compounds are described and discussed.     

Stereochemistry and active conformation of a novel insecticide,acetamiprid

Acetamiprid, (NI-25; (E)-N¹-[(6-chloro-3-pyridyl)methyl]-N²-cyano-N¹-methylacetamidine), is a novel neonicotinoid insecticide having an N-cyanoacetamidine structure as its characteristic feature. The [¹H] and [¹³C]-NMR spectra indicated the existence of two different structures in acetamiprid at room temperature in solution. The measurement of CH-NOE and C–C coupling constants proved the E-configuration at the cyanoimino group in both existing structures. The [¹³C] chemical shifts of N-CH₃ and the long range C–H coupling in the formamidine analogue of acetamiprid suggested that there exist two conformers generated by the rotation of C–C single bond in the amidine moiety. Dynamic NMR spectra of acetamiprid and the computer simulation of the two-site exchange demonstrated that the two conformers change slowly to each other at room temperature. The conformational analysis by semi-empirical molecular orbital calculations using MNDO-PM3 method predicted four conformers as energy-minimum structures, among which two E-conformers were more stable than Z-conformers. One of the E-conformers in which two methyl groups are in cis configuration was superimposable onto the structure of imidacloprid, which is a known neonicotinoid insecticide having more rigid structure. This E-conformer was assumed as the active conformation of acetamiprid on the basis of the molecular similarity in terms of steric and electrostatic properties. © 1997 SCI     

Recent progress in the field of N-acylalanines as systemic fungicides

The influence of structural variations in compounds of the N-acylalanine type, on their fungicidal activity towards Peronosporales, was examined. Within a series of methyl N-(acyl)-N-(2,6-xylyl)alaninates ( I ), a quantitative structure-activity relationship was given for the curative action against Plasmopara viticola, through a Hansch-type equation. A deviation from this equation is discussed with reference to benalaxyl ( I ; acyl=phenylacetyl). Syntheses and qualitative indications of activity are reported for structural changes in the xylyl and in the alanine moieties. Progress in the latter approach is briefly outlined.