Stabilization of the pesticide Fenitrothion toward O and N nucleophiles in the presence of cyclodextrins

The reaction of Fenitrothion with O and N nucleophiles (H₂O₂, NH₂OH, n‐butylamine and piperidine) was studied at 25 °C in water containing 2% 1,4‐dioxane in the presence of native cyclodextrins (α‐, β‐, and γ‐CD). For all the nucleophiles, the presence of CD produces reaction inhibition with saturation kinetics. The greatest effect in all cases is observed with β‐CD, and the greatest inhibition was observed for the reaction of Fenitrothion with H₂O₂ (81%), which is the most efficient nucleophile in promoting Fenitrothion degradation in homogeneous media. In the absence of CD, competition between the S_N2(P) and the S_N2(C) pathways was observed with piperidine as was reported before for the reaction with NH₂OH and n‐butylamine. The presence of β‐CD does not modify product distribution in the case of the reaction with NH₂OH and n‐butylamine, whereas there is an increase in S_N2(C) pathway when the nucleophile is piperidine. Copyright © 2014 John Wiley & Sons, Ltd.     

The acid/base profile of agrochemicals

Drug-likeness has long been studied in the pursuit of finding new medicines. Similarly, in the agrochemical field there is value in exploring the properties of the chemicals involved. Patterns that emerge can potentially influence future discovery campaigns to improve the probability of commercial success. In this study we investigate the acid/base properties and physicochemical characteristics of three classes of compounds: fungicides, herbicides and insecticides. In comparison with FDA-approved drugs, it was noted that the pesticides were generally smaller, possessed a neutral charge state and were more lipophilic. The results are discussed in the light of their intended targets.     

Immobilization of acetylcholinesterase on one-dimensional gold nanoparticles for detection of organophosphorous insecticides

This paper reports a simple method for immobilization of acetylcholinesterase (AChE) on one-dimensional (1D) gold (Au) nanoparticles for detection of organophosphorous (OP) insecticides. 1D Au nanoparticles were prepared by electrodeposition in the pores of an alumina template which was subsequently removed by 2.0 M NaOH solution. They were characterized by XRD and FESEM. The immobilized AChE retained its biological activity and catalyzed the hydrolysis of acetylthiocholine to form thiocholine, which was su...     

Amino Alcohols from Eugenol as Potential Semisynthetic Insecticides: Chemical,Biological, and Computational Insights

A series of β-amino alcohols were prepared by the reaction of eugenol epoxide with aliphatic and aromatic amine nucleophiles. The synthesized compounds were fully characterized and evaluated as potential insecticides through the assessment of their biological activity against Sf9 insect cells, compared with a commercial synthetic pesticide (chlorpyrifos, CHPY). Three derivatives bearing a terminal benzene ring, either substituted or unsubstituted, were identified as the most potent molecules, two of them displaying higher toxicity to insect cells than CHPY. In addition, the most promising molecules were able to increase the activity of serine proteases (caspases) pivotal to apoptosis and were more toxic to insect cells than human cells. Structure-based inverted virtual screening and molecular dynamics simulations demonstrate that these molecules likely target acetylcholinesterase and/or the insect odorant-binding proteins and are able to form stable complexes with these proteins. Encapsulation assays in liposomes of DMPG and DPPC/DMPG (1:1) were performed for the most active compound, and high encapsulation efficiencies were obtained. A thermosensitive formulation was achieved with the compound release being more efficient at higher temperatures.     

Synthesis of New Spiro-Cyclopropanes Prepared by Non-Stabilized Diazoalkane Exhibiting an Extremely High Insecticidal Activity

The synthesis of new insecticidal gem-dimethyspiro-cyclopropanes derived from pyrrolidine-2,3-dione have been described, and their biological effect against different insect species has been evaluated. The presented results demonstrate the excellent insecticidal activity of cyclopropane 5c against Aedes aegypti and Musca domestica. Cyclopropane 5c showed the quickest knockdown and the best killing against Aedes aegypti and Musca domestica compared to trans-chrysanthemic acid and pyrethrin. The biological results of the high insecticidal activity were confirmed by the results of docking. This is evident in the binding affinity obtained for cyclopropane 5c, indicating good binding with an important active amino acid residue of the 5FT3 protein.     

气相色谱-质谱法测定蔬菜中有机磷杀虫剂和克百威的残留量

利用气相色谱-质谱（GC-MS），电子轰击离子化（EI）法同时测定及确证蔬菜中多种有机磷农药和克百威的残留量。对样品的前处理方法进行了选择实验。试样用乙腈提取，将提取液过滤后，加氯化钠使水相与乙腈分离，浓缩有机相，无需净化。用GC-MS的选择离子监测（SIM）方法测定其中的敌敌畏、甲胺磷、甲拌磷、氧乐果、甲基对硫磷、克百威共6种杀虫剂的残留量并进行阳性确证。该方法的检测限量为0.0002mg/kg-0.016mg/kg,10种蔬菜6种农药的标准添加（0.01、0.02、0.1、0.2mg/kg)的回收率为72%-125%，测定相对标准偏差为6.7%-20%。本方法可以满足这6种杀虫剂的在蔬菜中的最高残留量限量的检测要求。     

Simultaneous quantitation of seven pyrethroid metabolites in human urine by capillary gas chromatography–mass spectrometry

Pyrethroid insecticides are applied in the residential environment, as well as in agricultural crops, for insect control purpose. We developed and validated an accurate, sensitive, and reproducible analytical method to simultaneously detect seven pyrethroid metabolites, namely, 3‐(2,2‐dichlorovinyl)‐2,2‐dimethyl‐(1‐cyclopropane) carboxylic acid, 3‐(2,2‐dibromovinyl)‐2,2‐dimethyl‐(1‐cyclopropane) carboxylic acid, 3‐phenoxybenzoic acid, 4‐fluoro‐3‐phenoxybenzoic acid, 2‐methyl‐3‐phenylbenzoic acid, 4‐chloro‐α‐isoproply benzeneacetic acid, and 3‐(2‐chloro‐3,3,3‐trifluoroprop‐1‐enyl)‐2,2‐dimethylcyclopropanecarboxylic acid, in human urine. This method employs deconjugation with enzyme, SPE using Agilent C18 cartridges on a RapidTrace SPE workstation, derivatization using hexafluoro isopropanol and N,N′‐diisopropylcarbodiimide, and compounds separation and identification on GC–MS. The detection limits of seven metabolites were 0.02–0.08 ng/mL in urine. The recoveries of seven metabolites were 81–104%, 85–99%, and 83–99% in urine specimens fortified at 0.1, 0.4, and 3.2 ng/mL concentrations, respectively. The overall coefficient of variation was 4.3–10.8% in two quality control specimens which were repeatedly measured during a period of 2 months. This method was applied to urine samples collected from children living in Boston, MA. The median concentrations of six detected pyrethroid metabolites ranged from 0.06 to 0.86 ng/mL in urine.     

果蔬中8种苯甲酰脲类农药残留量的液相色谱-串联质谱法测定

建立了果汁蔬菜中8种苯甲酰脲类(杀虫脲、氟苯脲、氟虫脲、氟啶脲、除虫脲、氟铃脲、灭幼脲、氟丙氧脲)农药残留量的液相色谱-电喷雾串联质谱(LC-ESI MS/MS)测定方法。样品用乙腈提取后无需净化,经盐析过滤并以水稀释(1∶1)后,经Waters Atlantis(d C18色谱柱分离,5 mmol/L乙酸铵水溶液和乙腈梯度洗脱,以电喷雾电离串联质谱在负离子多反应监测(MRM)模式下进行测定并确证,外标法定量。8种苯甲酰脲类农药在1.0~100μg/L范围内线性良好,相关系数为0.990 0~0.999 9。对8种农药在毛豆基质中3个添加水平下的回收率进行测定,平均回收率为92%~110%,相对标准偏差为5.5%~12%。方法的检出限(S/N=3)为0.04~0.42μg/kg,定量下限(S/N=10)为0.2~1.5μg/kg。     

Contamination by Organochlorine Pesticides in the Estuaries of Southeast China* 06 A

Persistent organic pollutants(POPs) such as organochlorine pesticides are of global concern due to their widespread occurrence and persistence. This paper reports recent research studying the distribution and fate of organochlorine pesticides in the Jiulong River, the Minjiang River and the Pearl River estuaries in Southeast China. Eighteen organochlorine pesticides were extracted from water, pore water and sediment samples, followed by analysis by GC-ECD. The results showed that the contamination levels were similar in these three estuaries.The levels of the total organochlorine pesticides in porewater were significantly higher than those in surface water, due to the high affinity of these hydrophobic compounds for sediment phase. Among the hexachlorocyclohexane (HCH) compounds, β-HCH was found to be the most important isomer. The analysis of 1, 1,1-trichloro-2,2-bis-chlorophenyl-ethane(DDT) and its metabolites showed that 1, 1-dichloro-2[o-chlorophenyl]-2[p-chlorophenyl]-ethylene (DDE) was dominant in the group.Koywords Organochlorine insecticides, DDT, Lindane, Jiulong River Estuary, Minjiang River Estuary, Pearl River Estuary, Water, Sediment