Eel acetylcholinesterase studies with the 4-nitrophenyl esters of monochloro-, dichloro-, and trichloromethyl(phenyl)phosphinic acid

The inhibition of eel acetylcholinesterase by the 4-nitrophenyl esters of monochloromethyl(phenyl)-, dichloromethyl(phenyl)-, and phenyl(trichloromethyl)phosphinic acid (I, II, and III, respectively) was investigated at pH 6.90 in 0.067 M phosphate buffer (25.0°C) using stopped-flow instrumentation and automated data processing. The largest k_i value (156,700 M⁻¹ sec⁻¹) was observed for the reaction of I with the enzyme. There is no direct relationship between the hydrolysis rates of the esters and their anticholinesterase activities on eel acetylcholinesterase. Spontaneous reactivation of the phosphinylated enzymes at pH 7.60 showed the following order of activity: I > III > II. The absence of aging is supported by oxime-induced reactivation studies.     

Stereoselectivity of acetylcholinesterase,arylester hydrolase,and chymotrypsin toward 4-nitrophenyl alkyl(phenyl)phosphinates

Acetylcholinesterases from electric eel and from bovine erythrocytes were inhibited stereoselectively by P(+) 4-nitrophenyl ethyl(phenyl)phosphinate (EPP) and P(+) 4-nitrophenyl isopropyl(phenyl)phosphinate (IPP). Bovine pancreatic α-chymotrypsin was inhibited stereoselectively also, but the P(−) enantiomers of both EPP and IPP were more active than P(+). Arylester hydrolase was nine times more active in the hydrolysis of P(−) EPP than P(+). Chiral-phase HPLC was employed to isolate the enantiomers from racemic mixture for experiments and to analyze reaction mixtures initiated with racemic EPP or IPP.     

含4-正庚/正辛氧基苯基杂环化合物的设计、合成及生物活性

通过研究苯甲脒类抑制剂与酮醇酸还原异构酶(KARI)对接的结合模式,设计合成了一系列含正庚氧基及正辛氧基苯基的杂环化合物。用核磁共振氢谱、红外光谱、质谱及元素分析对26个目标产物(其中22个是新化合物)的结构进行了表征和确认。初步生物活性测试结果表明,目标化合物大多具有不同程度的水稻KARI酶抑制活性和除草活性,其中化合物 9a和9b 在200 μg/mL浓度下对KARI酶的抑制率分别为65.7%和71.1%,在100 μg/mL浓度下对双子叶植物油菜Brassica campestris的抑制率分别达78.6%和89.0%。     

5-(羟基亚甲基)-2,4-咪唑啉二酮酯的合成及除草活性

在实验室原有的AdSS酶抑制剂研究工作基础上,以丝氨酸为原料设计合成了9个未见文献报道的2,4-咪唑啉二酮酯类化合物,其结构经核磁共振氢谱、红外光谱、元素分析或质谱等验证。初步生物活性测试结果表明,化合物 3g 在质量浓度200 μ g/mL下对拟南芥Arabidopsis thaliana的发芽抑制率达到70%,表现出一定的除草活性。     

Preparation of (R)-2-(4-hydroxyphenoxy) propionic acid by biotransformation

With Beauveria bassiana Lu 700 as biocatalyst an ecologically beneficial process has been developed for the production of (R)-2-(4-hydroxyphenoxy) propionic acid. The fungal strain used in this process, B. bassiana Lu 700, is also a very suitable catalyst for the selective monohydroxylation of other aromatic carboxylic acids.     

The insecticidal and anticholinesterase activities of O,O-diethyl O-4-(2,2-disubstituted vinyl)phenyl phosphates and phosphorothioates

A series of O,O-diethyl O-4-(2,2-disubstituted-vinyl)phenyl phosphorothioates and phosphates was synthesised and examined for anticholinesterase activity to housefly and bovine erythrocyte ChE, and also for their toxicity to Musca domestica and Triatoma infestans. The synthesised phosphates were potent anticholinesterases and stronger inhibitors of housefly acetylcholinesterase than bovine erythrocyte acetyl-cholinesterase. Satisfactory correlation was obtained between the anticholinesterase activity and the Hammett σ^? constants against both enzymes, but it was not significantly improved by introducing a term for the Hansch π constant. The phosphorothioates showed poor and variable toxicity to M. domestica. On T. infestans, the only compound that showed some toxicity was the di(acetyl)-substituted product [O-4-(2-acetyl-3-oxobut-1-enyl)phenyl O,O-diethyl phosphorothioate]. For comparative studies, some commercial products were also assayed on T. infestans.     

(2E,4Z )-Decadienoic acid and (2E,4Z,7Z )-decatrienoic acid,two herbicidal metabolites from Streptomyces viridochromogenes Tü 6105

Two fatty acids, (2E,4Z)-decadienoic acid and (2E,4Z,7Z)-decatrienoic acid, the latter being described for the first time as a natural product, were detected in the culture filtrate of Streptomyces viridochromogenes Tü 6105 by HPLC-diode array screening, purified by chromatographic methods and structurally elucidated by NMR techniques. Both metabolites show strong herbicidal activity against Lemna minor and Lepidium sativum. The herbicidal activities of the isolated compounds were compared with those of similar fatty acids and derivatives. © 1999 Society of Chemical Industry     

Comparative studies of acetylcholinesterases purified from two field populations of the oriental migratory locust (Locusta migratoria manilensis): implications of insecticide resistance

Acetylcholinesterase (AChE) was purified by affinity chromatography from two populations of the oriental migratory locust, Locusta migratoria manilensis (Meyen), collected from Huanghua and Pingshan Counties, Hebei Province of China. The purification factors and yields were 1661-fold and 19.3%, respectively, for the Huanghua population, and 3897-fold and 39.6% for the Pingshan population. Both the purification factor and yield were significantly lower in the Huanghua population than in the Pingshan population. AChE activity was almost completely inhibited by 10⁻⁶ M eserine and BW284C51, but ?5.8% of AChE activity was inhibited by ethopropazine at the same concentration, suggesting that purified AChE from either population was a typical insect AChE. However, AChE purified from the Huanghua population was 62-, 2.0-, and 1.6-fold less sensitive to inhibition by the three organophosphate compounds, chlorpyrifos oxon, demeton-S-methyl, and paraoxon, respectively, than that from the Pingshan population. Significantly lower purification factor and low yield associated with reduced sensitivity of AChE to inhibition by the organophosphates indicated that AChE purified from the Huanghua population was biochemically and pharmacologically different from that of the Pingshan population. Reduced sensitivity of AChE appeared to contribute to organophosphate resistance in the locust from Huanghua County, where insecticides have commonly been used to manage outbreaks of the locust.     

含磷苯甲酰基硫脲的合成及杀虫活性

通过 α- 氨基膦酸酯与取代苯甲酰基异硫氰酸酯反应,合成了10个新的含磷苯甲酰基硫脲化合物 5a~5h, 其结构均经核磁共振氢谱、质谱、红外光谱和元素分析确证。初步的生物活性试验表明,化合物 5j 在500 mg/L质量浓度下对蚜虫的致死率为88%。     

Selectivity and mode of action of flamprop-isopropyl,isopropyl (±)-2-[N-(3-chloro-4-fluorophenyl)benzamido]propionate,in the control of Avena fatua in barley

The post-emergence herbicide isopropyl (±)-2-[N-(3-chloro-4-fluorophenyl)benzamido]propionate (flamprop-isopropyl) showed good activity against wild oat with selectivity in barley. The basis for activity and selectivity was similar to that previously established for benzoylprop-ethyl, and found to be dependent on its rate of degradation to the biologically active acid flamprop. Flamprop stunted the growth of the oat by inhibiting cell elongation and showed a relatively high rate of movement in the phloem, approximately five times that of benzoylprop. Selectivity of flamprop-isopropyl was dependent on its relative rate of hydrolysis and the subsequent detoxication of the acid to inactive conjugates. However, although the relative rate of de-esterification of flamprop-isopropyl was lower than that of benzoylprop-ethyl similar quantities of the parent ester gave comparable effects on oat. The inherent activity of flamprop is approximately twice that of benzoylprop. The effect of flamprop-isopropyl was best seen when the compound was applied during growth stages when the crop could offer the most effective competition to the wild oat. Throughout a range of growth stages the rate of hydrolysis of flamprop-isopropyl was higher in oat than in barley. The metabolism of the compound was not markedly affected when the plants were under stress.     

Inhibition of chitin synthesis by two 1-(2,6-disubstituted benzoyl)-3-phenylurea insecticides. II

The knowledge of the biochemical mode of action of 1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl)urea (diflubenzuron) is presented, explaining the insecticidal effect. Like its structural analog, 1-(2,6-dichlorobenzyl)-3-(3,4-dichlorophenyl)urea (Du 19111), it inhibits chitin synthesis in the cuticle of larvae. Virtually complete inhibition was demonstrable 15 min after the application of diflubenzuron. Neither diflubenzuron nor Du 19111 has any effect upon chitinase activity either in vivo or in vitro. The insecticidal effect upon the cuticle, therefore, must be explained as an inhibition of chitin synthesis and not as an activation of chitin degradation. In contrast to the action of Du 19111, no accumulation of N-acetylglucosamine occurs upon treatment of larvae with diflubenzuron. Similarities and differences in the mode of action of both compounds are discussed, together with other effects reported in the literature.     

Animal metabolism of propham (isopropyl carbanilate): The fate of residues in alfalfa when consumed by the rat and sheep

Alfalfa was root-treated with [¹⁴C]propham (isopropyl carbanilate[¹⁴C-phenyl(U)]) for 7 days and then harvested and freeze-dried. Rats and sheep were orally given either ¹⁴C-labeled alfalfa roots ([¹⁴C]root) or ¹⁴C-labeled alfalfa shoots ([¹⁴C]shoot). When the [¹⁴C]root was given, 6.5–11.0% of the ¹⁴C was excreted in the urine and 84.6–89.4% was excreted in the feces within 96 h after treatment. Less than 3% of the ¹⁴C remained in the carcass (total body—gastrointestinal tract and contents) 96 h after treatment. When [¹⁴C]shoot was given, 53.2–55.2% of the ¹⁴C was excreted in the urine, 32.1–43.4% was excreted in the feces, and the carcass contained 0.2–1.1% of the ¹⁴C 96 h after treatment. When the insoluble fraction (not extracted by a mixture of CHCl₃, CH₃OH, and H₂O) of both alfalfa roots and shoots was fed to rats, more than 86% of the ¹⁴C was excreted in the feces and less than 3% remained in the carcass 96 h after treatment. The major radiolabeled metabolites in the urine of the sheep fed ¹⁴C shoot were purified by chromatography and identified as the sulfate ester and the glucuronic acid conjugates of isopropyl 4-hydroxycarbanilate. Metabolites in the urine of the sheep treated with [¹⁴C]root were tentatively identified as conjugated forms of isopropyl 4-hydroxycarbanilate, isopropyl 2-hydroxycarbanilate, and 4-hydroxyaniline. The combined urine of rats dosed with [¹⁴C]shoot and [¹⁴C]root contained metabolites tentatively identified as conjugated forms of isopropyl 4-hydroxycarbanilate, isopropyl 2-hydroxycarbanilate, and 4-hydroxyaniline.     

Preparation and biocidal activity of alkyl phenyl (dichloromethyl)phosphonates

Seventeen new alkyl (or phenacyl) phenyl (dichloromethyl)phosphonates were synthesised; seven of these showed poor fungicidal activity when tested in vitro against Pyricularia oryzae but some possessed high insecticidal activity against Culex fatigans and Drosophila melanogaster.     

Effects of acute and multiple dose administration of Sumithion (O,O-dimethyl O-(3-methyl-4-nitrophenyl) phosphorothionate) on some enzymes of Periplaneta americana (Linn.)

Acute exposure to Sumithion (65.0 μg/g dose) causes significant inhibition of acetylcholinesterase (AChE) in the digestive tissue of adult P. americana. At this dose there is practically no effect on the activities of either acid or alkaline phosphatases or non-specific esterases. Exposures to multiple doses of 1.3 μg/g at intervals of 24 and 48 hr, respectively, lower AChE activity by approximately 40%. On the other hand multiple doses cause an initial rise in the activities of phosphatases, indicating their possible involvement in the metabolism of the pesticide. However, later on, there is a decrease in levels of acid and alkaline phosphatase activities. This is coupled with a steady rise in nonspecific esterase activity indicating a possible take over of metabolizing role by these enzymes.     

Inhibition of ergosterol biosynthesis in Ustilago maydis by the fungicide 1-[2-(2, 4-dichlorophenyl)-4-ethyl-1, 3-dioxolan-2-ylmethyl]-1H-1, 2, 4-triazole

Inhibition of sporidial multiplication in cultures of Ustilago maydis by 1-[2-(2, 4-dichlorophenyl)-4-ethyl-1, 3-dioxolan-2-ylmethyl]-1H-1, 2, 4-triazole^a (CGA-64251), at concentrations of 0.1, 1.0 and 5.0 μg ml^?1, increased from about 15% during the first 4 h, to 58–70% during the subsequent 4 to 12-h period. Sporidia became swollen and highly branched in the presence of the fungicide. Total lipid content as a percentage of the dry weight was not affected after exposure of the sporidia to the fungicide at 0.1 or 5 μg ml^?1 for 4 h, but synthesis of ergosterol and other demethyl-sterols was inhibited by 87–92%. Large quantities of methyl-sterol precursors of ergosterol and of free fatty acids accumulated in the treated sporidia. Fungitoxicity of CGA-64251 is attributed to inhibition of ergosterol biosynthesis at the stage of sterol C-14 demethylation.     

Determination of individual esters of 2, 4-D and 2, 4, 5-T in commercial crops

A rapid gas chromatographic method for the determination of the individual esters of 2, 4-D and 2, 4, 5-T in tomato plants and other commercial crops is described. Several suitable esters can be determined at one time. Separation is by steam distillation into a hexane trap followed by clean-up on a column of “Florisil”. Using a sample of plant material (100 g), 1 μg of each of the esters in the mixture can be determined with recoveries of 72–96% for 2, 4-D esters and 66–84% for 2, 4, 5-T esters.     

3-二氟甲基-1-甲基吡唑-4-羧酸肟酯衍生物的合成及抑菌活性

为发现具有高抑菌活性的先导化合物,结合本课题组前期研究,设计并合成了18个新型3-二氟甲基-1-甲基吡唑-4-羧酸肟酯衍生物,其结构均经核磁共振氢谱、碳谱及高分辨质谱分析确证,化合物 9g 的单晶衍射结果证明肟酯的构型为E式。离体生物活性测定结果表明,目标化合物在50 μg/mL下对番茄灰霉病菌 Botrytis cinerea、苹果树腐烂病菌Valsa mali 和小麦全蚀病菌Gaeumannomyces graminis均表现出一定的抑制活性,其中化合物 9d 对苹果树腐烂病菌、 9r 对小麦全蚀病菌的EC₅₀值分别为0.89 μg/mL和3.34 μg/mL,表现出比先导化合物 L1 (E-2-氯-6-氟苯甲醛-O-(1-甲基-3-苯基-1H-吡唑-5-羰基)肟)和肟菌酯更优或相似的抑菌活性。     

Studies on pesticides based on coumarin IV: Synthesis and antifungal activity of twelve 4-(substituted phenoxy)methyl-6-methyl coumarins

Twelve 4-(substituted phenoxy)methyl-6-methyl coumarins were synthesised by the condensation of 4-chloromethyl-6-methyl coumarin with various phenols in the presence of potassium carbonate in dry acetone. The compounds were tested for their toxicity towards the mycelial growth of seven plant pathogenic fungi. Among the tested fungi, Pythium aphanidermatum, Colletotrichum falcatum, Drechslera oryzae, Alternaria alternata and Fusarium solani exhibited maximum sensitivity whereas Macrophomina phaseolina and Rhizoctonia solani were least sensitive to the test compounds. The 4-(4-tert-butylphenoxy)methyl and 4-(4-nitrophenoxy)methyl analogues possessed greatest toxicity towards the majority of the tested fungi.     

Herbicide perfluidone (1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl]methanesulfonamide): Its metabolism in rats and chickens

Rats and chickens were each given a single oral dose (10 or 100 mg/kg body wt) of 1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl-¹⁴C(U)]methanesulfonamide ([¹⁴C]perfluidone). Depending on the size of the dose, from 8.4 to 36.2% of the [¹⁴C] was eliminated in the urine and from 36.4 to 85.4% was eliminated in the feces within 48 hr after dosing. Less than 1% of the [¹⁴C] given to laying hens as [¹⁴C]perfluidone was present in the eggs produced during the first 96 hr after dosing. The percentage of the administered [¹⁴C] that remained in these animals (body with G.I. tract and contents removed) varied from 0.34 (96 hr after dosing) to 1.68% (48 hr after dosing). ¹⁴C-labeled compunds in the urine and feces from the rats and chickens were purified by solvent extraction, column chromatography, and gas-liquid chromatography, and then identified by infrared and mass spectrometry. The parent compound was the major ¹⁴C-labeled component in the urine and feces of both animals. 1,1,1-Trifluoro-N-[2-methyl-4-(3-hydroxyphenylsulfonyl)phenyl]methanesulfonamide was present in the feces of both animals. The proposed structures of other metabolites were 1,1,1-trifluoro-N-hydroxy-N-[2-methyl-4-(phenylsulfonyl)phenyl]methanesulfonamide (rat urine) and 1,1,1-trifluoro-N-{2-methyl-4-[(methylsulfonyl)-phenylsulfonyl]phenyl}methanesulfonamide (chicken urine).