Diastereoisomers and enantiomers of paclobutrazol: Their preparation and biological activity

Paclobutrazol is a highly active plant growth regulator with very good fungicidal activity. Aspects of the synthesis of paclobutrazol and its diastereoisomer are discussed, the resolution of paclobutrazol into its two enantiomers is described. It has been shown for the first time that it is possible to separate the plant growth regulatory activity from the fungicidal activity by resolution. Computer graphic studies are also included.     

The chemistry and biological activity of a new class of azole fungicides: 1-amino-1,2,4-triazoles

The fungicidal activity of a novel class of triazole compounds in which the 1-position of the azole nucleus is bonded to a nitrogen atom was investigated. Such 1-amino-1,2,4-triazoles are amenable to great structural variation which allows the elucidation of the requirements for biological activity. As in most other triazole fungicides, the basic structural requirement for activity is a two-atom bridge connecting the azole nucleus to a hydrophobic group, typically an aromatic ring. The synthesis and optimization of fungicidal activity of this class of triazole fungicide are discussed.     

Effects of physical properties on the translaminar activity of fungicides

Translaminar redistribution is a key component of activity for many fungicides. The influence of physical properties (including water solubility, lipophilicity, melting point, and molar volume) on translaminar activity, however, is not well understood. Cucumber powdery mildew was used as a biological indicator to examine the influence of physical properties on translaminar activity of 61 fungicides in simple, uniform formulations, including three modes-of-action and a range of physical properties. Results were modeled using multiple regression and ordinal logistic fit. We confirmed that translaminar activity is a frequent attribute of fungicides and that lipophilicity and water solubility are important predictors of translaminar activity. The hypothesis that melting point drives translaminar movement and translaminar activity was not supported. Translaminar movement (driven only by physical properties) could be differentiated with the models from fungitoxicity-influenced translaminar control. Translaminar activity is a complex attribute and differences in inherent activity as well as physical properties and formulations must be considered when comparing compounds for relative translaminar activity.     

Influence of chlorine substituents on biological activity of chemicals: a review

A number of well known polychlorinated chemicals are toxicologically and environmentally unsafe. Because of their persistence they are in the focus of public discussions against chlorine chemistry. However, chlorinated organic chemicals in the molecular weight range between 200 and 600 constitute an important and indispensable segment in the arsenal of existing biologically active chemicals used as pharmaceuticals or crop‐protection agents. Over the course of time it has been found empirically that the introduction of a chlorine atom into one or more specific positions of a biologically active molecule may substantially improve the intrinsic biological activity. In some cases the presence of a chlorine atom is crucial for significant activity in compounds derived both from nature and chemical synthesis. But in other cases chlorination diminishes or abolishes biological activity, as shown for chlordane homologues. Thus a chlorine atom, like any other substituent, is a modulator of activity. Almost all non‐reactive chlorinated chemicals and chlorine‐free chemicals are devoid of any biological activity at the highest concentration typically used in primary screening tests for discovery of useful biological properties. The influence of a substituent such as chlorine on the biological activity of a potential drug or crop protection agent still has to be established empirically in biological experiments designed to detect desired activity or toxicological properties. Sometimes chlorine does prove to be the optimum for improvement of activity. Long‐term rigorous investigations of several hundred chlorinated compounds, registered by the authorities as pharmaceutical drugs or crop‐protection agents, show that the generalisation ‘all chlorinated chemicals are dangerous’, deduced from the negative toxicological properties of a hundred chlorinated and reactive compounds of low molecular weight that are relevant in terms of safe working conditions in the chemical industry and for ecological safety, is not justified. Chlorinated compounds are not necessarily toxic or dangerous. Highly reactive chemicals or polychlorinated compounds cannot be compared with regard to toxicological properties with unreactive compounds having a low degree of chlorination. The chlorine atom, as one of many possible substituents used in synthetic organic chemistry, will remain in the future one of the important tools for probing structure–activity relationships in life science research and as a molecular component in commercialised compounds, in order to provide safer, more selective and more environmentally compatible products with higher activity for medicine and agriculture. © 1999 WILEY‐VCH Verlag GmbH     

Observation of saltation activity at Tazhong area in Taklimakan Desert,China

A two-year field observation of saltation activity was carried out at Tazhong area,the hinterland area of the Taklimakan Desert with highly frequent dust storms.From 1 September 2008 to 31 August 2010,a piezoelectric saltation sensor(Sensit) was used to continuously collect the data on saltation activity at a level sand surface.Analysis on the data suggests that saltation activity can occur at any time of the year when conditions are favorable;however,the necessary conditions are rarely satisfied in most time.In the daytime of spring or summer,saltation activity can persist even over a continuous one-hour-or-so period.It is found that,from 1 September 2008 to 31 August 2010,saltation activity accounts for more than 3% of the total yearly time,and it tends to peak in spring and summer months with strong winds.During winter months when winds are weak,however,it is often at a minimum.It seems that precipitation does not appear to be significant in reducing saltation activity in arid regions like Tazhong.     

Some factors affecting the activities of dinitrophenol fungicides

The vapour phase and protectant activities of members of seven homologous series of alkyldinitrophenols against cucumber powdery mildew (Oidium sp.) are discussed. No correlation existed between vapour activities in vitro or in vivo and vapour pressure, but a positive correlation between Vapour' protection in vivo and conventional protectant activity was evident. Although vapour activity occurs with some homologues, results obtained for zone assays in vivo are probably better explained in terms of easy movement of the compound in the leaf surface than in terms of vapour transmission. Alkyldinitrophenyl-crotonates showed no zone activity in vivo but often good protectant activity. The possible existence of two optimum π-values for protectant activity is suggested. No appreciable systemic activity was found with these compounds.     

Variation in the sensitivity of Callosobruchus (Coleoptera: Bruchidae) acetylcholinesterase to the organophosphate insecticide malaoxon: effect of species, geographical strain and food type

BACKGROUND: Bruchid beetles, Callosobruchus species, are serious pests of economically important grain legumes; their activity in stores is often controlled by the use of synthetic insecticides. Esterases are known to be involved in insecticide resistance in insects. However, there is a dearth of information on esterase activity in the genus Callosobruchus. In this study, the effect of species, geographical strain and food type on the variation in acetylcholinesterase (AChE) activity and its inhibition by malaoxon (malathion metabolite) was investigated using an in vitro spectrophotometric method. RESULT: AChE activity varied significantly among species and strains and also among legume type used for rearing them. Generally, irrespective of species, strain or food type, the higher the AChE activity of a population, the higher is its inhibition by malaoxon. C. chinensis had the highest AChE activity of the species studied, and in the presence of malaoxon it had the lowest remaining AChE activity, while C. rhodesianus retained the highest activity. CONCLUSION: A first‐hand knowledge of AChE activity in regional Callosobruchus in line with the prevailing food types should be of utmost importance to grain legume breeders, researchers on plant materials for bruchid control and pesticide manufacturer/applicators for a robust integrated management of these bruchids. Copyright © 2012 Society of Chemical Industry     

Effect of light environment on the activity and behaviour of diquat and paraquat in plants

The importance of controlling the light environment of experiments involving diquat and paraquat is shown in experiments where activity is markedly dependent on the light quality and intensity before treatment and on the time of day of treatment. Activity and uptake are not directly related since treatments after low light intensities give increased activity associated with reduced uptake; following afternoon treatments, reduced activity is associated with increased uptake. Uptake increased when plants were darkened after treatment but the increase was not directly related to its duration, because after a time, uptake decreased. Three possible explanations for this decrease are considered: diquat exudation from the leaves, downward movement into the roots, and the adsorption of diquat in plant tissue. Evidence did not support exudation from leaves or downward movement into the roots.     

β-cyclodextrin inclusion complexes of pyrethroids

Pyrethroids are more stable to practical conditions when included in β-cyclodextrin, particularly because photodecomposition is reduced. Though inclusion sometimes decreases the contact insecticidal activity, the innate activity is regenerated under conditions which release the free pyrethroids. Stabilised dust and wettable powder formulations of natural pyrethrins show promising insecticidal effects to certain pest insects.     

The Synthesis and Insecticidal Activity of a Series of 2-Aryl-1,2,3-triazoles

Two synthetic routes to 2-aryl-1,2,3-triazoles are outlined. These have been used to synthesise a wide range of compounds of this structural type. Their insecticidal activities were evaluated against a number of veterinary and public health pests. The activity of these compounds is especially good against the housefly (Musca domestica). Structure–activity relationships are discussed particularly in relation to the physical properties of the compounds.     

白蚁肠道可培养菌群及其功能初探

白蚁是一种危害严重的昆虫,其以破坏木质而家喻户晓.文献表明,白蚁对木质强大的消化能力很大程度上取决于其肠道微生物的影响.为了探究白蚁肠道微生物的类群,本试验以黑翅土白蚁为材料,分离纯化获得其肠道主要可培养微生物的纯培养112种,其中喜氧菌35种,厌氧菌77种;在分离出的微生物类群中,通过刚果红法初步筛选出12种喜氧菌菌株可能具有纤维素酶活性,其最大透明圈达到4.0㎝×4.0㎝;进一步检测这些菌株的纤维素酶活性发现,12株菌均具有羧甲基纤维素钠盐(CMC-NA)酶活性和滤纸酶活性,但是大部分菌株羧甲基纤维素酶活性较弱,而一些菌株如 NBY14滤纸酶活较高,可达到16.188u/mL.试验结果可为黑翅土白蚁防治提供依据,亦可为纤维素酶的开发利用奠定基础.     

Activity of the botanical aphicides 1,5‐diphenyl‐1‐pentanone and 1,5‐diphenyl‐2‐penten‐1‐one on two species of Aphididnae

1,5‐Diphenyl‐1‐pentanone (A) and 1,5‐diphenyl‐2‐penten‐1‐one (B) are natural products extracted for the first time from Stellera chamaejasme. Laboratory bioassay showed that the two products have strong contact activity and very good anti‐feedant activity against Aphis gossypii and Schizaphis graminum. Both products showed dose‐dependent relationships for both forms of activity against the two aphids, the contact activity of B being about twice that of A. Both products were inferior to methomyl in contact activity but superior in anti‐feedant activity against the two aphids. This is the first report of aphicidal activity in these two compounds, which may represent a new class of aphicide. © 2001 Society of Chemical Industry     

Oils for weed control: Uses and mode of action

The role of oils in herbicide treatments is reviewed, both in terms of their own intrinsic activity and of their enhancement of the performance of other herbicides. The phytotoxicity of oils can be related to their physical properties. Their efficacy as adjuvants can vary with the plant/pesticide combination involved, and differences may also be observed between oils of mineral and vegetable origin. The possible mechanisms involved in the enhancement of activity by oils are discussed and areas of work that might elucidate these fun her are indicated.     

半干旱地区水土流失因素的定量分析——以甘肃中部半干旱地区祖历河流域为例

本文从地貌演化角度,探讨了土壤侵蚀过程的动力学机理。认为土壤侵蚀过程受控于内力和外力两种营力过程及人类活动过程的共同作用。在内力相对稳定的时期内,土壤侵蚀过程主要依靠外力过程和人类活动过程共同完成;水力侵蚀是半干旱地区土壤侵蚀的主要方式之一,影响土壤侵蚀的外力因素主要是流量与降水。笔者以甘肃中部半干旱地区祖历河流域为例,运用灰色系统理论的灰色关联分析方法为手段,研究揭示了输沙量流量与降水指标之间的关系,提出了半干旱地区水土流失过程的产流、产沙函数,由此导出了水土流失因素定量分析的数学模型,并分析了祖历河流域五十年代初期至八十年代中期,人类活动对减水、减沙效益的贡献。     

Aerial Transport of Pests and Pest Outbreaks1

Pests of arable crops tend to show a high degree of migratory activity. This is particularly so in northern Sudan where the variable rainfall produces habitats which are short-lived and unpredictable in their frequency and location. Insects whose flight activity is adapted to enable them to move on the same wind-system which produces the rains are frequently pests of the crops of these climates. Outbreaks of such pests are usually a function of the numbers which colonise the crops, and this in turn depends not only on the success of breeding in the source areas but also on increases in density which occur whilst they are airborne. The importance of the increases in airborne densities which occur within the inter-tropical discontinuity and the cold-air outflows ahead of convectional storms to pest outbreaks in the Sudan Gezira is described.     

Insecticidal activity of 3-isoxazolyl methanesulfonates and related compounds

Various methanesulfonates, notably of 3-isoxazolols, exhibit interesting insecticidal activity, especially against Musca domestica and Locusta migratoria. Although the symptoms of poisoning are very similar to those caused by parathion, no correlation between in-vitro inhibition of acetylcholinesterase and insecticidal activity was observed. This is also true for several methanesulfonates of hydroxy-heterocycles and phenols included in this study for comparison.     

Choline acetyltransferase in organophosphorus-resistant and -susceptible strains of the cattle tick, Boophilus microplus

Choline acetyltransferase was demonstrated in homogenate extracts of larvae and adult brains of the cattle tick. The enzyme activity was approximately 15 and 100 μmol of acetylcholine synthesized/g of tissue/hr for larvae and adult brains, respectively. Comparisons of five strains showed that, despite organophosphate selection for acetylcholinesterases with wide differences in activity and inhibition kinetics, the choline acetyltransferase activity was statistically uniform between strains. it is concluded that the two enzymic components of the cholinergic system are controlled independently.     

不同浓度铁离子对黄芩抗氧化酶活性等生理特性的影响

对不同浓度铁离子处理下黄芩抗氧化酶活性等生理特性进行了研究,结果表明:M4处理(Fe2+浓度为6.95 mg/kg)下黄芩的株高最高,其叶绿素含量、SOD酶活性、POD活性、可溶性蛋白质含量均显著高于其他处理,而其丙二醛含量却显著低于其他处理。研究结果提示,Fe2+浓度为6.95 mg/kg可有效增强黄芩细胞活性,促进黄芩生长,是黄芩生长的最佳铁离子浓度。     

Fungicidal activity and chemical constitution XIX. The synthesis and activity of substituted cyclohexylphenols

Twenty-two substituted 2- and 4-cyclohexylphenols were synthesised and tested in the glasshouse against the powdery mildews of apple and marrow. Relative differences in fungicidal activity between the two series are discussed in relation to structural variations. High activity is associated with a nitro group in position 4 together with either a halogen or nitro-group in position 2.     

软腐欧氏杆菌在离体条件下产生胞外酶的比较研究

 3种软腐细菌在21,26和31℃下及6种培养液中的生长量和产生胞外酶的能力各不相同。Ecc在26℃生长最好,Eca为21℃,Ech在三种温度下的生长量差别不大。与其它2种细菌比较,Ech的生长及产生果胶裂解酶(PL)的能力总是最强的。随着温度的升高,各种细菌的PL活性都下降。果胶水解酶(PG)变化不大,但Ech在高温下产PG有减少趋势,且总没有另二种细菌的活性强。Eca以26℃时产PG最适宜。Ech在较高温度下蛋白酶活性大大下降,而Ecc,变化不大,Eca的蛋白酶活性则随温度升高而加强。培养液的无细胞滤液对马铃薯块茎组织的浸离力与其中PL的活性有密切关系,但没有或只有很低果胶酶活性,而蛋白酶活性正常的这种滤液也能使小薯碟浸离。Eca在31℃培养后果胶酶活性很低,蛋白酶活性很高,其无细胞滤液对马铃薯组织也表现较强浸离力。