手性农药毒性机制的对映体选择性

综述了手性农药在急性毒性、慢性毒性、细胞毒性、藻类与植物毒性及生物体富集方面的对映体选择性差异。大量研究显示,手性农药的不同对映异构体对于非靶标作用体的毒性存在显著差异,这种选择性差异既取决于手性农药的对映异构体,同时又与作用的受体相关。探讨了手性农药毒理学研究的重点和发展方向——在对映体水平上对手性农药的毒理机制进行全面深入的研究,对于评价农药对健康的风险及生产绿色高效的单一或复合的对映体农药具有指导意义。     

《手性农药与农药残留分析新方法》

<正>出版时间:2015-03-01出版社:科学出版社ISBN:9787030436344定价:$280.00元开本:16内容简介:本书介绍了多种手性农药的分离分析方法及环境行为。利用色谱技术建立了不同环境样本中手性农药对映异构体的分离分析方法,系统地总结了手性农药对映异构体在土壤、水体、动物和植物等样本中的选择性行为,较为详细地描述了手     

二氯喹啉酸的生态毒理学研究进展

本文介绍了除草剂二氯喹啉酸的残留活性及其选择性机理,以及国内外有关二氯喹啉酸对陆生动物、水生生物、作物和土壤微生态影响方面的研究进展。     

手性农药选择性生物活性与毒性效应研究进展

手性农药因对映体在生物活性、毒性、环境行为等方面的差异性而备受关注,充分了解对映体的立体选择性对开发高活性农药及减量使用具有重要意义。本文聚焦手性农药对映体的立体选择性效应,系统地调研了对映体生物活性和毒性选择性差异,并进行了分类梳理,重点综述了手性农药对映体的生物活性及毒性和环境风险的差异性,阐述了手性农药对非靶标生物造成的氧化应激、内分泌干扰等慢性毒性,同时关注选择性的规律与机制,为环境友好型高效手性农药的开发、手性农药的风险评估及管理、手性农药对映体立体选择性机制研究提供参考。     

手性农药己唑醇和腈菌唑对黄酒酿造微生物酶活性的影响

在食品发酵过程中,残留的农药会对酿造微生物及产品组分产生一定影响,而酶在此过程中发挥着关键作用。作者在对映异构体水平上研究了手性农药己唑醇和腈菌唑对黄酒酵母和米曲霉中典型酶的酶活性和蛋白质含量的影响。结果表明:不同农药对映异构体对微生物酶活性的影响存在显著差异,其中:（+）-己唑醇对黄酒酵母超氧化物歧化酶（SOD酶）活性具有较明显的抑制作用,而（-）-己唑醇则对其有激活作用;低浓度的（+）-腈菌唑对黄酒酵母脂肪酶活性的抑制作用小于（-）-腈菌唑,而高浓度（+）-腈菌唑对脂肪酶活性的抑制作用却大于（-）-腈菌唑;（+）-己唑醇对米曲霉中的脂肪酶活性有明显的激活作用,而（-）-己唑醇对其则有抑制作用。本研究结果证明,手性农药对映异构体对发酵微生物酶活性的影响存在差异,并可能影响黄酒的组分和品质,使黄酒安全性存在较大风险。     

三唑醇及其对映异构体在3种不同类型土壤中的降解动态

实验室条件下,初步研究了手性农药三唑醇及其非对映异构体三唑醇A(对映异构体1R,2S体和1S,2R体的混合物)与三唑醇B(对映异构体1R,2R体和1S,2S体的混合物)在浙江杭州潮土(有机质含量1.90%,pH 6.85)、金华水稻土(有机质含量1.63%,pH 4.94)和兰溪红土(有机质含量0.38%,pH 4.03)中的降解动态及对映体之间相互转化的情况。结果表明:三唑醇在潮土、水稻土和红土中的降解半衰期分别为56.4、105.0和154.0 d,180 d时降解率分别为91.9%、79.2%和57.7%;三唑醇在潮土中发生两次三唑醇A体向B体转化和1次三唑醇B体向A体的转化,而在水稻土和红土中,三唑醇A体与B体之间相互各转化1次。表明三唑醇对映异构体的降解动态因土壤性质不同而存在差异。研究结果为三唑醇的科学合理使用及其环境风险评估提供参考。     

化学除草的选择性原理

选择性除草剂是一类能杀死杂草或严重抑制杂草生长而又不大伤害庄稼的农药。除草剂仅在一定的范围内对某些作物具有选择性,其选择的范围取决于多种因素。由于在任何地区都存在着植物、环境和除草剂之间复杂的相互关系,这些关系变化无常,环境条件与施药方法不同,除草剂的灭草效果亦不一样。了解化学除草的选择性,有助于提高除草的效果。植物的作用植物(包括杂草和作物)对除草剂的反应受其遗传、叶龄、生长速度、形态和生理以及生物物理和生物化学过程等因素的影响,不同属(genus)的植物反应是不同的,而同属植     

除草剂的选择性试验

除草剂能杀死杂草或抑制杂草生长,而对作物无害或危害很小的特性叫除草剂的选择性。造成选择性的原因是多方面的,如植物的生长习性和形态差异,不同植物对药剂吸收和传导的差异以及进入植物体内生化反应的差异,人为地控制播种深度(位差)和播种时间(时差),改进药剂的剂型,环境因素等都可造成除草剂的选择性。除草剂的选择性是相对的,所有的除草剂对任何植物都有毒性。当除草剂施用量太大时,可能杀死所有的植物,而用量太低时,也可能所有植物并不受害。但使用这两种极限之间的某一剂量时,有的植物会     

禾草灵的作用机制及环境生态效应研究进展

禾草灵 (diclofop-methyl)属芳氧苯氧丙酸类除草剂,广泛应用于禾本科杂草防除,其降解受到土壤有机质含量、pH值、氧气等众多因素的影响。母体化合物禾草灵及其主要降解产物禾草灵酸都具有除草活性,并会对环境中的一些非靶标生物产生急性或慢性毒性,是一类环境内分泌干扰物及过氧化物酶体增殖剂;同时,由于部分杂草产生抗性,进而演替成优势种群,迫使禾草灵的用量增加,更加重了其环境压力。文章就禾草灵的作用机制,其在环境中的降解、吸附等行为以及对非靶标生物的生态效应进行了综述,探讨了其中存在的一些问题,如生态毒理尤其是对映体差异性在毒性方面数据的缺乏等,并对今后的发展方向进行了展望。     

四种乳酸菌对马拉硫磷的手性选择性降解研究

乳酸菌广泛存在于自然界，为明确其对手性农药马拉硫磷的选择性降解情况，采用CHIRALCEL OD-H手性色谱柱及高效液相色谱分析方法，研究了马拉硫磷对映异构体的拆分以及在植物乳杆菌 Lactobacillus plantarum subsp. plantarum、干酪乳杆菌 Lactobacillus casei 、保加利亚杆菌 Lactobacillus delbrueckii supsp. bulgaricus及嗜热链球菌 Streptococcus thermophilus 4种乳酸菌存在条件下的选择性降解。MRS培养基中的马拉硫磷经乙腈提取，弗罗里硅土柱净化。结果显示:将4种乳酸菌分别以体积分数0.5%和5.0%的接种量接种于加有马拉硫磷标准溶液的MRS培养基后，乳酸菌在培养过程中的0~24 h内生长速率最快，36 h后趋于稳定，pH值在0~24 h内从7降到5，而对照pH值稳定在7；马拉硫磷两个对映异构体半衰期分别在5.4~6.5 d、5.1~6.3 d之间，与对照组半衰期接近，表明乳酸菌不会引起马拉硫磷的选择性降解。     

Action mechanisms of acetolactate synthase-inhibiting herbicides

Herbicides that target the acetolactate synthase (ALS) are among the most widely used weed control chemicals since their introduction into the marketplace in the early 1980s, including five classes (sulfonylureas, imidazolinones, triazolopyrimidines, pyrimidinylthio (or oxy)-benzoates and sulfonylamino-carbonyltriazolinones). The mechanism researches have progressed unprecedentedly in the last two decades. Primary mode of action of the ALS-inhibiting herbicides that interfere with the activity of ALS enzyme seems no longer in doubt. Three lines of investigation from physiology, genetics, molecular and chemical structure aspects came together to prove that ALS is the site of action. Researches on the effects of branched chain amino acids (BCAAs) synthesis or protein metabolism caused by ALS-inhibiting herbicide elicit lots of disputations. Besides these two main works, other secondary effects of ALS inhibition, such as buildup of 2-ketobutyrate (α-ketobutyrate or 2-KB) or 2-aminobutyrate (2-AB, the transamination product of 2-KB), depletion of intermediates of the pathway for some critical processes, disruption of photosynthesis transport and respiration system etc., have also been implicated in the mechanism of plant death. However, there are still some disputations and doubts on the precise mechanisms that need further probing into. Further more, as many ALS-inhibiting herbicides and their derivatives are chiral with one or even more enantiomers, which may behave quite differently in biochemical processes, the effects and the environmental fate of chiral herbicides need to be investigated stereospecifically. By this, we can have a better understanding about the herbicides and avoid unnecessary pollution load.     

Stereoselective metabolism of fipronil in water hyacinth (Eichhornia crassipes)

The enantioselective metabolism of racemic fipronil in water hyacinth (Eichhornia crassipes) had been investigated. In this study, the degradation data and the enantiomer fraction (EF) were determined by chiral high-performance liquid chromatography (HPLC) with a column cellulose-tri-(3, 5-dimethylphe-nylcarbamate)-based chiral stationary phase (CDMPC-CSP). During the uptake phase, the EF value of plant sample increased from 0.50 at 1st day to 0.72 at 63rd day, while it was almost unchanged in water. For the depuration phase, the S- and R-enantiomer of fipronil in water hyacinth plants were degraded 92.22% and 82.07% after 17 days, respectively. The process of the degradation of the two enantiomers was followed first-order kinetics (R² ? 0.94). Stereoselective behavior was observed in both accumulation and degradation process. In this study, fipronil-sulfone and fipronil-sulfide, the metabolites of fipronil, were detected by GC-MS to show the main metabolic pathway of fipronil in water hyacinth.     

Triticeae plants preferentially responded to S-1-α-methylbenzyl-3-p-tolylurea in root growth and tetrazolium reduction assays

Optically active 1-α-methylbenzyl-3- p -tolylurea (MBTU) shows diverse plant physiological properties. Gramineae plants exhibit enantioselective root growth inhibition by R / S -MBTU. In the present paper, the dose–growth response (DGR) towards the optically active MBTUs was examined in the tribe Triticeae plants, including Hordeum vulgare L., Secale cereale L., Triticum aestivum L. and Aegilops cylindrica Host., and compared with those of the genus Bromus ( B. inermis Leyss), which is classified into the tribe Bromeae, and the genus Oryza . In spite of their phylogenetic difference, the Triticeae plants responded homogeneously in their chiral recognition. Of particular interest, is the result of the dichotomic enantioselective response of tested Gramineae plants. Only the genus Oryza responds to R -MBTU, and the tribes Triticeae ( Triticum , Aegilops , Secale and Hordeum ) and Bromeae ( Bromus ) preferentially respond to the S -enantiomer. The tetrazolium–phenazine methosulfate–formazan (TPF) assay was demonstrated to measure redox activity of root tips of the MBTU-treated Oryza sativa and T. aestivum , which are the typical dichotomic, enantioselective-responsive plants. In Oryza and Triticum root tips, enantioselective responses of reduction activity in TPF assays were strongly related to those of root growth inhibition in DGR assays, suggesting aggressive participation of the MBTU in the generation of the reducing mechanism in mitochondria.     

敌草胺对映体的高效液相色谱分离及手性拆分热力学研究

利用直链淀粉三-(3,5-二甲基苯基氨基甲酸酯)手性固定相(AD-RH柱)和纤维素三-(3,5-二甲基苯基氨基甲酸酯)手性固定相(OD-RH柱),以乙腈-水为流动相,对敌草胺对映体进行了直接手性拆分研究。考察了流动相组成、流速、柱温等对敌草胺对映体的色谱保留和分离的影响,并对敌草胺对映体与固定相之间的色谱保留和分离的热力学机理进行了讨论。结果表明,在流速为0.5mL/m in、乙腈-水为50∶50(体积比)、柱温在1035℃条件下,AD-RH和OD-RH柱的△△H0值分别为-1 160.79和-673.40J/mol,即AD-RH柱的拆分能力优于OD-RH柱,二者都能实现基线分离。     

Influence of herbicides on photosynthetic activity and transpiration rate of intact plants

The effect of various herbicides on photosynthesis, respiration and transpiration of intact plants has been studied in a routine assembly. Simultaneous measurements were made under different experimental conditions in four small plant chambers, in which the shoots of various plant species can be accommodated. The herbicide is applied during measurement, so that the effect can be related to the photosynthetic activity of the same plants before treatment. The selectivity of various herbicides was studied by determining the capacity of a plant species to inactivate a herbicide absorbed by the roots. These and other differential effects of various herbicides on photosynthetic activity of different plant species coincide with the selective properties in the field. Such differences are also observed after leaf sprayings. The duration of the experiments is kept short. Bean plants were studied under various experimental conditions of air humidity, light intensity and temperature resulting in different transpiration rates. The decrease in photosynthetic activity owing to the presence of a herbicide in the nutrient solution at a standard concentration was more rapid at the higher transpiration rates. The total transpiration during treatment up to 50% inhibition of photosynthesis was constant under the various experimental conditions. Specific inhibitors of the photosynthetic process had a more pronounced effect on the photosynthetic activity than on transpiration rate. Some other herbicides affect transpiration as well as photosynthesis.     

SELECTIVITY AND PHYSIOLOGICAL INACTIVATION OF SOME HERBICIDES INHIBITING PHOTOSYNTHESIS

Summary. The effects of several herbicides on the rates of CO₂ uptake and transpiration of intact plants were measured. A simple technique is described which reveals whether photosynthesis-inhibiting herbicides are inactivated by plants. By this method, the inactivation of simazine by maize could be confirmed. Evidence is presented for physiological inactivation of monuron by Plantago lanceolata , of cycluron (OMU) and pyrazon by sugar beet, of N'-(4-butoxyphenyl)-NN-dimethylurea by of 5-bromo-6-methyl-3-phenyluracil by flax. Certain plant species showed different reactions to some other new herbicides. The effect of herbicides in the culture solution on CO₂ uptake by the leaves is probably largely determined by the rate of transpiration of the plants. Assuming that uptake in proportional to transpiration rate, estimates of the concentration of the herbicides inside the plant were made.
L'inactivation physiologique de quelques herbicides produisant une inhibition de la photosynthèse     

三唑醇对映体的反相高效液相色谱拆分热力学研究

在高效液相色谱反相条件下,利用涂敷型纤维素-三(3,5-二甲基苯基氨基甲酸酯)手性固定相(CDMPC-CSP)对三唑醇4个对映异构体进行了直接手性拆分研究。考察了不同流动相组成和柱温对三唑醇对映体的色谱保留及分离的影响。同时,利用热力学方法对三唑醇对映体与固定相之间的色谱保留和分离的热力学机理进行了探讨。结果表明:在以甲醇-水(70∶ 30,体积比)为流动相、流速0.8 mL/min、柱温15 ℃,或在以乙腈-水(30∶ 70,体积比)为流动相、流速1.0 mL/min、柱温45 ℃的条件下,三唑醇对映体可以得到较好分离。     

Metabolism and selectivity of rice herbicides in plants

Chemical weed control with effective and highly active herbicides has been very useful and convenient means. It has contributed to stable crop production and is labor saving. Recent herbicides have had characteristics such as high effectiveness without causing environmental pollution or harmful effects, and appropriate herbicides having high activity, low toxicity, high selectivity and being non-persistent have been developed. The metabolism of rice herbicides used mainly in Japan, such as sulfonylurea, chloroacetamide, acylamide, urea, thiocarbamate, pyrazole, triazine, diphenyl ether, phthalimide, phenoxy, aryloxyphenoxypropionate, etc., is reviewed, and its involvement in selectivity is also discussed. The metabolism of herbicides is closely related to their activity and selectivity. Differential herbicide metabolism in plants is a contributing factor of selectivity between crops and weeds. Chemicals that are more detoxified in crops and/or more activated or less detoxified in weeds are considered as being effective and selective herbicides. The metabolism of various types of rice herbicides includes: oxidative reaction (ring and chain hydroxylation, O - and N -dealkylation), hydrolysis and subsequent glucose conjugation, and glutathione conjugation in rice. These detoxicative activities are much higher in rice than weeds in paddies, and this leads to the selectivity of herbicides. Enzymes, oxidase, P-450 mono-oxygenase, esterase, acylamidase, glucosyl transferase, glutathione transferase, etc., play important roles in herbicide metabolism and selectivity.