流动相添加剂法与手性固定相法对己唑醇光学异构体的拆分

分别采用β-环糊精作为手性流动相添加剂的反相高效液相色谱法和涂敷型纤维素-三(3,5-二甲基苯基氨基甲酸酯)正相高效液相色谱手性固定相法拆分了农药己唑醇。结果表明,己唑醇对映异构体在以上两种方法下都完全达到基线分离。考察了影响容量因子、选择性系数和分离度的各种因素。     

腈菌唑在番茄果实中的立体选择性降解

为明确田间条件下手性杀菌剂腈菌唑对映体在番茄果实中的降解规律，采用Lux Cellulose-1手性色谱柱及超高效液相色谱-串联三重四极杆质谱 (UPLC-MS/MS) 分析方法，研究了腈菌唑对映体的分离及其在番茄果实中的选择性降解。样品经乙腈提取，采用QuEChERS 方法净化。分析方法验证结果表明:在0.000 5~0.05 mg/L线性范围内，腈菌唑对映体的峰面积与其浓度间呈良好的线性关系，R2均大于0.99；在0.005、0.05和0.25 mg/kg 3个添加水平下，腈菌唑对映体在番茄中的平均回收率在92%~96%之间，相对标准偏差 (RSD) 在1.0%~3.0%之间。降解试验结果显示:腈菌唑对映体在番茄果实中的降解规律符合一级反应动力学方程，其降解半衰期在2.77~4.08 d之间；腈菌唑对映体在番茄果实中的降解具有明显选择性，随时间延长，其对映体分数 (F_E) 值由最初的0.47下降为0.24，其中S-(+)-腈菌唑优先降解，从而导致R-(–)-腈菌唑的相对富集。本研究从对映体的角度评价了腈菌唑在番茄中的降解，可为手性农药对映体的环境行为研究提供基础数据。     

己唑醇及其对映体对人体乳腺癌细胞的选择毒性及氧化损伤研究

在对映体水平上研究己唑醇对人体乳腺癌细胞 (MCF-7) 的选择毒性及氧化损伤。以MCF-7细胞作为受试对象，采用Cell Counting Kit-8 (CCK-8) 试剂盒测定经己唑醇对映体处理后的细胞毒性；采用氧化损伤相关试剂盒测定经己唑醇对映体处理后，细胞内乳酸脱氢酶 (lactate dehydrogenase, LDH) 释放量、活性氧 (reactive oxygen species, ROS) 产生量、超氧化物歧化酶 (superoxide dismutase, SOD) 和过氧化氢酶 (catalase, CAT) 的活性。结果表明:在10 ~ 160 mg/L范围内随着染毒质量浓度的增加，经过 (?)-、(+)- 和rac-己唑醇处理后的MCF-7细胞活性分别从85.24%、87.11%和103.87%降低至4.07%、5.11%和5.24%。其中，(?)-己唑醇对MCF-7细胞活性的抑制率最高，其次是 (+)- 和rac-己唑醇。氧化损伤检测结果显示，MCF-7细胞经20、40和80 mg/L的己唑醇对映体暴露后，细胞内LDH释放量和CAT酶活性随着己唑醇质量浓度的增加而逐渐增加，而ROS产生量和SOD酶活性则随着己唑醇质量浓度的增加呈现出先上升后下降的趋势。与细胞毒性结果相似，经3种形式的己唑醇处理后，(?)-己唑醇诱导的细胞氧化损伤程度最高，其次是 (+)- 和rac-己唑醇。本研究结果表明，己唑醇及其对映体在MCF-7细胞内的毒性和氧化损伤程度大小顺序为 (?)-己唑醇 > (+)-己唑醇 > rac-己唑醇。研究结果可为探明己唑醇的细胞毒性机制和开展食品安全风险评估提供依据。     

己唑醇铜配合物抑菌活性与植物生长调节效能

利用目前主流三唑类杀菌剂之一的己唑醇与醋酸铜复配合成己唑醇铜配合物,通过抑菌活性以及植物生长调节活性研究评价新型已唑醇铜配合物的功能特性.结果表明,己唑醇铜配合物对酵母生长的抑制作用强于配体己唑醇,其中浓度为0.05 mmol·L-1配合物的抑菌圈直径是相当浓度己唑醇的1.48倍;同时配合物能够降低植物株高、增加根冠比,提高植物SOD和POD酶活,促进GSH和可溶性蛋白合成,0.03mmol· L-1配合物处理相比对照SOD活性增加了24.65％,POD活性增加了61.06％,GSH含量增加了30.41％,叶绿素含量增加了59.04％;抑制MDA积累,具有植物生长调节活性,其抗氧化特性也优于己唑醇配体.     

黄瓜白粉病菌对己唑醇抗性诱导及抗性菌株生物学性状的研究

室内通过紫外线照射和药剂驯化相结合的方法连续诱变7代,获得了黄瓜白粉病菌Sphaerotheca fuliginea对己唑醇的抗性菌株,该抗性菌株对己唑醇的抗性水平达到105倍,其产孢量和致病力比敏感菌株略高,但差异不显著,且对戊唑醇、腈菌唑、多抗霉素和嘧菌酯无交互抗性,对醚菌酯表现交互抗性,结果表明田间用己唑醇防治黄瓜白粉病可能存在抗性风险。     

含两个手性中心的三唑类杀菌剂色谱分离研究进展

三唑类杀菌剂是目前世界上广泛应用的杀菌剂,而绝大多数三唑类杀菌剂属于手性农药,具有1个或2个手性中心,存在2个或4个对映异构体。本文在近年有关三唑类杀菌剂研究成果的基础上,综述了采用高效液相色谱、超临界流体色谱、毛细管电泳、气相色谱和合相色谱法等方法对含两个手性中心的11种三唑类杀菌剂 (氟环唑、多效唑、三唑醇、联苯三唑醇、丙环唑、苯醚甲环唑、叶菌唑、苄氯三唑醇、环唑醇、糠菌唑和乙环唑) 进行分离测定的研究进展,可为多个手性中心三唑类化合物的分离、分析和深入研究提供参考。     

异噁唑草酮对玉米根际土壤微生物量碳、氮和酶活性的影响

为明确异噁唑草酮对玉米根际土壤微生物碳、氮及酶活性的影响, 采用田间试验的方法, 以1倍、5倍和10倍田间推荐剂量为供试除草剂剂量, 测定了异噁唑草酮土壤封闭处理对玉米根际土壤微生物量碳、氮及土壤脲酶、过氧化氢酶、蔗糖酶、脱氢酶和中性磷酸酶活性的影响。结果表明:推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮含量无显著影响, 5倍和10倍推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮含量具有抑制作用。推荐剂量的异噁唑草酮对玉米根际土壤脲酶、过氧化氢酶和蔗糖酶影响较小, 5倍和10倍推荐剂量的异噁唑草酮对其具有明显的抑制作用。异噁唑草酮对土壤脱氢酶活性具有抑制作用, 且施用剂量越高, 抑制作用越强。异噁唑草酮对土壤中性磷酸酶活性的影响表现为前期促进, 后期抑制, 且施用剂量越大, 促进或抑制作用越强。研究表明:推荐剂量的异噁唑草酮对玉米根际土壤微生物量碳、氮及土壤脲酶、过氧化氢酶和蔗糖酶活性的影响较小, 但对土壤脱氢酶、中性磷酸酶活性有影响。     

己唑醇对水稻纹枯病的毒力测定及田间药效试验

根据水稻纹枯病菌在含己唑醇系列浓度的PDA培养基上的菌丝生长速率,计算出己唑醇对水稻纹枯病菌的毒力回归方程为:Y=4.0407+2.3632x,r=0.9971,药剂EC₅₀=2.5464mg/L,EC₉₅=12.6463mg/L,试验结果表明己唑醇对水稻纹枯病菌具有较高的生物活性。田间药效显示,5％己唑醇悬浮剂250mg/667m²药后15d防效达69.54％。     

环丙唑醇对映体的反相高效液相色谱分离及其热力学研究

在高效液相色谱反相条件下,利用手性色谱柱Lux Cellulose-1(纤维素-三(3,5-二甲基苯基氨基甲酸酯,粒径分别为3μm和5μm)对环丙唑醇4个对映异构体进行了直接手性拆分研究。考察了不同粒径、流动相组成和柱温对环丙唑醇对映体色谱保留及分离的影响;并采用在线旋光检测器研究了环丙唑醇对映体的洗脱顺序;同时,利用热力学方法对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:以乙腈-水为流动相比甲醇-水具有更好的拆分效果,柱温降低有利于对映体的拆分;在以V(乙腈)∶V(水)=60∶40为流动相、柱温为20℃的条件下,环丙唑醇对映体在3μm(流速0.3 m L/min)和5μm(流速1.0 m L/min)色谱柱上均可得到较好分离,在满足对映体完全分离的情况下,建议优先使用3μm色谱柱,异构体洗脱顺序为(+/+/-/-);而当流动相由乙腈-水变为甲醇-水时,对映体的洗脱顺序则变为(+/-/+/-)。热力学研究结果表明:在5~40℃试验温度范围内,van't Hoff方程的线性关系良好(R20.92);以乙腈-水作为流动相时,环丙唑醇对映体的拆分过程受焓驱动;而以甲醇-水为流动相时,对映体的拆分过程既受焓驱动又受熵驱动。     

甘肃省南瓜白粉病菌对己唑醇抗性诱导及抗性菌株生物学性状研究

为了解甘肃省裸仁美洲南瓜白粉菌对己唑醇敏感性及抗性产生情况,采用小株喷雾法对采自兰州、武威、景泰等地的20个南瓜白粉菌菌株对己唑醇的敏感性进行了测定,利用紫外诱导、药剂驯化、先紫外后药剂驯化三种方法对敏感菌株进行了抗药性诱导,并对抗性突变菌株的生物学性状及其对丙环唑、氟硅唑、腈菌唑和戊唑醇的交互抗性进行了研究。结果表明20个南瓜白粉菌菌株对己唑醇的敏感性存在一定差异,EC50值在17.77~285.54μg/mL范围内;与其他两种诱导方法相比药剂驯化方法获得的抗性突变菌株的抗性倍数最高,为8.94倍。敏感菌株和抗性突变菌株孢子萌发的最佳时间分别为36h和48h;抗性突变菌株产孢量和致病力明显高于敏感菌株;适合度测定表明抗性突变菌株与敏感菌株之间存在竞争力,孢子萌发率、芽管个数之间差异显著,菌丝分支数、产孢量之间差异不显著;抗性突变菌株在抗性突变菌株和敏感菌株混合比例为80∶20的群体中,存在频率比较稳定,连续培养7代后仍占85.69%;己唑醇抗性突变菌株对丙环唑、氟硅唑、腈菌唑和戊唑醇4种药剂未表现出交互抗性。研究结果可为甘肃省防治南瓜白粉病提供理论依据。     

The effect of the annual use of some pesticides on soil microorganisms,pesticide residues in soil and carrot yields

The study deals with the effect of common, annually-used pesticides on soil microorganisms, pesticide residues in soil, and carrot (Daucus carota) yields in Central Finland. Linuron residues in carrot roots were also analysed. Thiram+lindane and dimethoate were applied from 1973–1981 at the commercially recommended doses on experimental plots of carrots, linuron was applied at twice the recommended rate from 1973–1979 and at the normal rate thereafter and in addition TCA was applied in 1978. Maleic hydrazide was used in the years 1973–1976, and glyphosate after 1977. The numbers of different soil microorganisms, their activities and the pesticide residues were studied from autumn 1978 to 1981. The pesticide treatments reduced the growth of soil algae but increased the total number of microorganisms and the number of aerobic spore-forming bacteria. Linuron residues in the soil were 0.9–2.8 mg kg^?1 in the growing season and 1.2–1.7 mg kg^?1 in the autumn, 3 months after application. The residues of glyphosate in the soil were 0.7 mg kg^?1 in the autumn, 41 days after the treatment, and had declined to a level of about 0.2 mg kg^?1 by the following summer. In the pesticide-treated plots the carrot yield was only 20–60% of the yield in the hand-weeded plots. The herbicide programme controlled most of the annual weeds but not couchgrass Elymus repens and milk sow-thistle Sonchus arvensis.     

Enantioselective degradation kinetics of metalaxyl in rabbits

Metalaxyl [methyl-N-(2′-methoxyacetyl)-N-(2,6-dimethylphenyl)-d,l- alaninate] is a potent phenylamide fungicide. The (−)-(R)-isomer accounts for most of the fungicidal activity. A possible stereo and/or enantioselective kinetics of metalaxyl in rabbits was investigated by intravenous injection. The concentrations of (−)-(R)- and (+)-(S)-metalaxyl in plasma, liver, and kidney tissue were determined by HPLC with a cellulose-Tris-(3,5-dimethylphenylcarbamate)-based chiral stationary phase and gas chromatography-mass spectroscopy. After intravenous administration of racemic metalaxyl (40 mg/kg), the (+)-(S)-enantiomer levels in plasma, liver, and kidney decreased more rapidly than the (−)-(R)-isomer. The area ratio of the (−)-(R)-/(+)-(S)-enantiomer under the concentration-time curve (AUC_0 → ∞) in plasma after drug application was 1.62. The total plasma clearance value of the (+)-(S)-enantiomer was 1.53 and higher than that of the (−)-(R)-enantiomer. The [R]/[S] ratio in plasma was >1 for standard rac-metalaxyl at each time point. The other pharmacokinetic parameters of the enantiomers were also different. The results indicate substantial stereoselectivity in the degradation of metalaxyl enantiomers in rabbits.     

Stereochemistry of fluazifop-butyl transformations in soil

Fluazifop-butyl was incubated with two soils under aerobic conditions at 20°C. Hydrolysis of the racemic herbicidal ester yielded a residue of the corresponding carboxylic acid, fluazifop, in which the R-enantiomer predominated. Further studies involving the treatment of soil with the separate enantiomers of fluazifop-butyl showed that the two enantiomers were each hydrolysed with retention of their optical configuration. However, the hydrolysis product with the S-configuration was inverted (50% inversion in 1-2 days) to yield, ultimately, a residue of the R-enantiomer with a high optical purity.     

Stereoselective degradation of ethofumesate in turfgrass and soil

The stereoselective degradation of ethofumesate in turfgrasses and several agricultural soils was investigated to provide details of the fate of this chiral herbicide. Racemic ethofumesate was either foliar applied to two species of turfgrass or fortified into four types of agricultural soils. (+)- and (−)-Enantiomers were extracted and analyzed by a validated chiral HPLC method which involved extraction of samples with organic solvent followed by separation on cellulose-Tris-(3,5-dimethylphenylcarbamate)-based chiral column and quantification by UV absorbance at 230 nm. Mean recoveries of each enantiomer fortified at 0.5, 5, and 10 μg g⁻¹ ranged from 82.3 ± 5.84 to 92.5 ± 2.87% in turfgrasses and from 86.0 ± 5.09 to 98.1 ± 2.51% in soil. As a measure of this composition, the enantiomeric ratio (ER) was used, defined as the concentration ratio of (+)/(−)-enantiomer. Similarly, preferential degradation of the (−)-enantiomer was observed in both grass species with the largest ER of about 3 and in one of the test soil with ER = 1.65, resulting in residues enriched with (+)-enantiomer. This stereoselective degradation in this soil led to significant difference on half-lives between the two enantiomers. No stereoselective degradation was observed in other soils.     

Green-odour compounds have antifungal activity against the rice blast fungus <Emphasis Type="Italic">Magnaporthe oryzae</Emphasis>

Four green-odour compounds—trans-2-hexenal, cis-3-hexenol, n-hexanal, and cis-3-hexenal—were applied (0.85 μg ml⁻¹ as vapour) to rice plants in laboratory conditions to observe their biological activity against the phytopathogenic fungus Maganporthe oryzae, which causes rice blast disease worldwide. Two compounds, trans-2-hexenal and cis-3-hexenal, showed remarkable disease suppression efficacy (99.7% and 100% suppression, respectively), while n-hexanal had moderate (86.5%) and cis-3-hexenol had weak (20.8%) disease-suppressing effects. Pre-application and post-application of trans-2-hexenal or cis-3-hexenal had slight effects on blast incidence, suggesting that these compounds had direct effects to suppress M. oryzae infection. In fact, trans-2-hexenal and cis-3-hexenal exhibited a growth suppression effect on M. oryzae. Interestingly, these two compounds inhibited appressorium formation at lower concentrations than the growth suppression. Studies on the hypersensitive response (HR)-like reaction and plant β-1,3-glucanase activity in rice plant confirmed that induced resistance was not the major factor involved in the disease suppression mechanism. Results of this study conclusively showed that trans-2-hexenal and cis-3-hexenal possess potent inhibitory activities against the growth and the appressorium formation of M. oryzae and could be used as antifungal agents to significantly reduce M. oryzae infections in rice.     

Study of catechin,epicatechin and their enantiomers during the progression of witches' broom disease in Mexican lime (Citrus aurantifolia)

Witches'broom diseases of Mexican lime (WBDL) caused by ‘Candidatus Phytoplasma aurantifolia, is a big threat to lime production in Southern Iran. In this investigation, concentration of catechin, epicatechin and their enantiomers were monitored during WBDL progression for 6 months. In addition, the activities of peroxidase (POD), phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS) as well as the content of malondialdehyde (MDA) were assayed. The results showed that after 30 days of inoculation, levels of catechin and epicatechin were considerably increased up to 390% and 290% respectively, but both of them significantly decreased after 150 days. These changes in the levels of catechin and epicatechin are in well agreement with the activities of PAL, CHS and POD as well as the level of MDA. Does WBDL influence on biosynthesis of enantiomers in lime? The analysis of catechin enantiomeric ratio of infected leaves demonstrated that after 30 days of inoculation, the ratio of (+)-catechin changed from 61:39 to 79:21 and then remained almost constant. Finally, the infection of lime by WBDL, not only induced the production of resistance enzymes (PAL and CHS) as well as catechin and epicatechin but also enhanced the accumulation of (+)-enantiomer.     

Influence of pesticides on the activity and kinetics of invertase,urease and acid phosphatase enzymes

The effects of four pesticides (three herbicides, atrazine, paraquat, glyphosate, and an insecticide, carbaryl) on the activity and kinetics of an invertase (from yeast), a urease (from jack bean) and an acid phosphatase (from potato) were investigated. Glyphosate and paraquat showed a marked activation effect on invertase activity. From the dependence of V_max and K_m parameters on pesticide concentrations, a mixed-type activation mechanism was suggested. The kinetic behaviour of urease and acid phosphatase appeared to be uninfluenced by both pesticides. Methanol, used as solvent for both carbaryl and atrazine, inhibited invertase, urease and acid phosphatase with, respectively, competitive, non-competitive and uncompetitive mechanisms. The extent of the inhibition was different, as estimated by the values of the inhibition constant K₁. An additional inhibition effect of urease and invertase activities was achieved in the presence of carbaryl, whereas no influence was detected on the activity and kinetics of acid phosphatase. Finally, atrazine was shown to alter the kinetics of the enzymes only at higher concentrations.     

Long‐term survival of blast pathogen in infected rice residues as major source of primary inoculum in high altitude upland ecology

Magnaporthe oryzae is the fungal plant pathogen that causes rice blast. The sources of primary inoculum and overwintering mode of the fungus remain largely unknown. The effect of rice residues on the onset of blast epidemics and the potential for survival of M. oryzae in the residues were studied in upland conditions in Madagascar. Blast disease was observed in a 3‐year field experiment in three treatments: with either infected or uninfected rice residues on the soil surface, or without rice residues. Leaf blast incidence was significantly higher in the treatment with infected rice residues than in the two other treatments at the early stages of the epidemic. In a second set of trials, the survival of M. oryzae on rice residues was monitored. Infected rice stems were placed by lots in three places: on the mulch of rice residues, under the mulch, and buried at a depth of 10 cm in the soil. Each month, samples were taken from the field and tested for sporulation. The survival of the blast fungus decreased rapidly on the stems buried in the soil but remained high for the other conditions. Sporulation of the fungus was observed on stems left on the mulch for up to 18 months. It is concluded that under field conditions, the presence of infected rice residues could initiate an epidemic of blast. The results of this study may help in designing effective management strategies for rice residues infected by M. oryzae.     

韭菜中毒死蜱残留量与高光谱特征参数的相关性建模

本研究目的在于分析农药残留量(pesticide residue,PR)与高光谱中响应特征参数之间的关系,并利用筛选的光谱特征参数建立反演毒死蜱残留量的有效模型。首先采用ASD Fieldspec高光谱仪测得韭菜样本的光谱,通过气相色谱-质谱联用(GC-MS)法测得毒死蜱残留量(PR)值;分析样本光谱反射率值及其一阶微分值与毒死蜱残留量的相关性,计算33个高光谱特征参数与毒死蜱残留量的相关性;根据相关系数高低选择敏感的光谱特征参数;最后采用最佳相关系数下的光谱特征参数对毒死蜱残留量进行建模反演。相关性分析结果显示:近红外波段789~867 nm范围内一阶微分光谱值与PR值呈正相关,1 860 nm处一阶微分光谱值(first-order differential 1 860 nm,FD1860)与PR值紧密相关;在33个高光谱特征参数中,近红外一阶微分总和(the sum of first-order differential near infrared,SDnir)与PR值呈良好的正相关关系。基于此,文章以供试样本的FD1860和SDnir观测值为自变量,分别建立了3个预测毒死蜱残留量的模型,即线性、二次多项式及指数模型,并采用交叉验证测试方法检验了模型的合理性。对实验所得决定系数R2和预测均方根误差(RMSE)的评价结果表明,以SDnir为自变量构建的模型稳定性强,其二次多项式模型是最佳反演毒死蜱残留量的有效模型。因此,样本的高光谱特征参数SDnir的变化幅度直接反映了韭菜样本中毒死蜱残留量的变化,表明运用蔬菜的高光谱特征参数反演蔬菜中农药残留量的方法是可行的。