Fungicidal activity and chemical constitution. XX. The activity of substituted 1,4-naphthohydroquinone esters and substituted 1,4-naphthoquinones against powdery mildews

Eleven 2-n-alkyl-, ten 2-n-alkyl-3-hydroxy- and ten 2-n-alkyl-2,3-epoxy-3-hydro-1,4-naphthoquinones, together with eighteen 1,4-naphthohydroquinone esters were tested as protectant fungicides against the apple and cucumber powdery mildews (caused by Podosphaera leucotricha and Sphaerotheca fuliginea respectively). In.general the former pathogen was more susceptible to compounds from all four series, the lowest 10⁵ED⁵⁰(M) being 0.7 for 2-n-octyl-2,3-epoxy-3-hydro-1,4 naphthoquinone.     

Fungicidal activity and chemical constitution: XVII.—Activity of various 4-(1-substituted n-alkyl)-2,6-dinitrophenols and esters against apple powdery mildew

Members of series of 4-(cyclobutylalkyl, cyclohexylalkyl and benzylalkyl)-2,6-dinitrophenols were tested in a glasshouse against apple powdery mildew caused by Podosphaera leucotricha. Three series involving a cyclohexyl substituent separated from the phenolic nucleus by one, two or three methylene groups were of the same order of activity, but replacement of this substituent by a phenyl group in one case, resulted in a marked decrease in activity. Of a number of esters tested, none was significantly more active than the corresponding phenol.     

Fungicidal activity and chemical constitution. xxii. substituted cyclopentylphenols

Twenty-two substituted 2- and 4- cyclopentylphenois were prepared and tested against apple powdery mildew, highest activity being shown by 2-cyclopentyl-6-iodo-4-nitrophenol. The cyclopentyl compounds were only marginally superior to the corresponding cyclohexyl analogues.     

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.     

Fungicidal activity and chemical constitution. XVIII. The activity of 4-(1-cyclo-, 1-iso- and 1-n-propylalkyl)-2, 6-dinitrophenols against powdery mildews

The synthesis of seven 4-(1-cyclopropylalkyl)- and eight 4-(1-isopropylalkyl)-2, 6-dinitrophenols is described. When tested, together with six 4-(1-n-propylalkyl)-2, 6-dinitrophenols, several of these compounds showed high protectant activities against apple and cucumber powdery mildews. Their activities are discussed in relation to π values obtained from g.l.c. retention times, and to hydrogen bonding characteristics (both intra-and inter-) derived from infrared spectroscopic data.     

The fungicidal activity of substituted 1, 4-naphthoquinones. Part 1: Alkylthio and arylthio derivatives

Some symmetrical and unsymmetrical 2, 3-bis(arylthio)-1, 4-naphthoquinones have been synthesised and assayed against Botrytis cinerea, Cladosporium fulvum and Venturia inaequalis. With the surprising exception of the 2, 3-bis(4-chlorophenylthio) derivative, the compounds were essentially inactive. The 2-phenylthio and lower 2-alkylthio derivatives showed a high level of activity, which was absent in the 2-pentylthio and higher homologues.     

The fungicidal activity of substituted 1, 4-naphthoquinones. Part II: Alkoxy,phenoxy and acyloxy derivatives

A representative group of 1, 4-naphthoquinone derivatives, bearing alkoxy, phenoxy and acyloxy substitutents in the 2-position, has been synthesised and assayed against Botrytis cinerea, Cladosporium fulvum and Venturia inaequalis. The alkoxy compounds exhibited moderate activity, which was enhanced by the presence of a 3-chloro and, to a lesser extent, a 3-bromo substituent. 2-Chloro-3-phenoxy derivatives were highly active, but diphenoxy compounds were inactive. Acyloxy derivatives possessed only weak activity unless a halogen atom was present in the 3-position; benzoyloxy compounds, however, were generally poor fungicides.     

Fungicidal activity and chemical constitution XXT. The fungitoxicity of aliphatic polyamines

Fifteen polyamines have been prepared and shown to inhibit spore germination of Penicillium expansum and Neurospora crassa in vitro, but not Erysiphe graminis, Sphaerotheca fuliginea or Podosphaera leucotricha; no activity was shown against S. fuliginea on marrow seedlings or P. leucotricha on apple seedlings. Spermine homologues were considerably more active than spermidine homologues, but greatest activity was shown by the two naturally occurring compounds.     

The fungicidal activity of substituted 1,4-naphthoquinones. Part III: Amino,anilino and acylamino derivatives

A variety of 2-amino-, 2-anilino- and 2-acylamino-1, 4-naphthoquinones, with hydrogen, chlorine, alkoxy, phenoxy, methylthio or phenylthio as the 3-substituent, have been synthesised and assayed against Botrytis cinerea, Cladosporium fulvum and Venturia inaequalis. With few exceptions, only the 2-acylamino compounds possessed appreciable fungicidal activity: this was of a high order in the cases of 2-prop-ionamido-, 2-N-methylacetamido-3-methylthio-, and 3-methoxy-2-N-methylacetamido-1, 4-naphthoquinones.     

茉莉酸对PR-1、PR-2、PR-5和Ta-JA2基因 表达以及小麦白粉病抗性的诱导

 为了探索小麦抗白粉病分子机理,明确茉莉酸对小麦白粉病抗性的诱导作用、对植物抗病性标志基因PR-1、PR-2、PR-5和本实验室克隆的1个新基因Ta-JA2的激活作用,以及抗病性变化与基因表达变化之间的相关性,本研究以感白粉病的小麦品种“中国春”、“濮麦9号” 和“周麦18”为材料,用茉莉酸甲酯（methyl jasmonate,MeJA）喷洒小麦幼苗叶片进行诱导,通过离体叶段培养法接种白粉菌（Blumeria graminis f. sp. tritici,Bgt）进行抗性鉴定;用实时定量PCR技术检测小麦叶片中PR-1、PR-2、PR-5和Ta-JA2基因的表达变化。结果表明MeJA处理可以显著提高“中国春”、“濮麦9号”和“周麦18”对白粉菌的抗病水平。茉莉酸处理显著激活了PR-1、PR-2、PR-5和Ta-JA2的转录。茉莉酸诱导的抗病性提高与抗病标志基因PR-1、PR-2、PR-5及Ta-JA2的表达增强呈正相关。植物激素茉莉酸是小麦抗白粉病反应的信号分子。     

Some factors affecting the activities of dinitrophenol fungicides. II.—Use of g.l.c. partition data in studies of chemical structure/fungicidal activity against powdery mildew

The application of partition data, derived by a gas-liquid chromatographic (g.l.c.) technique, to the study of the activities of members of homologous 4-(l-substituted alkyl)-2,6-dinitrophenol series against cucurbit and apple powdery mildews (caused by Oidium sp. and Podosphaera leucotricha respectively) is discussed. The correlation between the possession of high protectant activity and a favourable πglc value for maximum ‘zonal’ movement within the leaf surface is stressed. This criterion is more important than vapour-phase activity in this context; it may well rival in importance the possession of optimum conidial penetration properties.     

Synthesis and anti-mildew activity of 5-(2-aroyl)aryloxymethyl-2-phenyl-1 ,3,4-oxadiazoles against downy mildew of pearl millet

A manipulatively simple, rapid, high-yielding and environmentally benign method for the integration of a heterocyclic ring, 1,3,4-oxadiazole, at the benzophenone nucleus has been achieved through intramolecular cyclization of substituted aroylaryloxyacetohydrazides to substituted 5-(2-aroyl)aryloxymethyl-2-phenyl-1,3,4-oxadiazoles under solventless 'dry' conditions using montmorillonite K10 clay and microwave irradiation. A comparison is made of the microwave-accelerated reaction with conventional heating conditions. Certain of the derivatives tested showed significant anti-mildew activity against Sclerospora graminicola (Sacc) Schroeter, the downy mildew pathogen of pearl millet.     

Synthesis and insecticidal activity of lipophilic amides. Part 5: Influence on activity of varying the substituent on nitrogen

Isomerisation or shortening of the 2-methylpropyl group in (2-methylpropyl)-6-phenylhexa-2, 4-dienamide lowers insecticidal activity, as does methylation at nitrogen. Methylation at each carbon atom in turn, and, within limits, in combination, gives compounds with substantial, sometimes increased, activity. Cyclic and olefinic equivalents of the effective alkyl substituents are mostly less active.     

Quantitative structure-activity studies of substituted benzyl chrysanthemates: 1. Correlations between symptomatic and neurophysiological activities against American cockroaches

A number of substituted benzyl (1R)-trans-chrysanthemates and related compounds were synthesized. Their symptomatic activities in terms of levels which induce convulsions as well as cause death in American cockroaches were determined by injection with and without application of synergists as inhibitors of metabolism. The neuroexcitatory and neuroblocking activities were also determined in terms of minimum effective concentrations to induce repetitive train of impulses and conduction blockage, respectively, to central nerve cords excised from the cockroaches and immersed in Ringer's solution. Correlations between symptomatic and neurophysiological activities were analyzed quantitatively with the aid of molecular hydrophobicity parameter and regression analysis. Each symptomatic activity from which the effect of metabolism is eliminated was found to be analyzable by means of a linear combination of indices for two types of neurophysiological activity when the transport factor is separated by using the hydrophobicity parameter. A closer correlation was found between neuroblocking activity and the “convulsive” effect than between neuroexcitatory activity and the “convulsive” effect, whereas both neurophysiological effects operate together on the cockroaches resulting in paralysis and death.     

Synthesis and insecticidal activity of lipophilic amides. Part 1: Introductory survey,and discovery of an active synthetic compound

A group of naturally occurring isobutylamides and related compounds exhibit a range of biological properties including activity against insects. Their potential as a starting point for developing new insecticides, needed to control pests resistant to other classes of insecticides, is discussed, following an extensive survey of known structures and activities. Few of the known compounds were sufficiently active and well characterised to point to sound structure-activity relationships, so synthetic analogues were examined. One of these [(2E,4E)-N-(2-methylpropyl)-6-phenylhexa-2,4-dienamide] was sufficiently active, and prompted the investigations reported here and in subsequent papers in the series. Analogues of this compound designed to establish areas where structural variation is possible are also described.     

Rhizome-induction activity of chiral 2-α-methylbenzylamino-4-alkylamino-6-chloro-1, 3, 5-triazines in Cyperus serotinus Rottb.

A cytokinin-like effect of chiral 2-α-methylbenzylamino-4-alkylamino-6-chloro-1,3,5-triazines was found using a rhizome-inducing assay with Cyperus serotinus Rottb. tubers. C. serotinus tubers germinated in distilled water yielded plantlets with roots and leaves. Secondary rhizomes were normally not observed within the regular 14-day incubation time in water culture, whereas after increasing incubation periods a very short rhizome appeared (controls). 6-Benzylaminopurine (BA) significantly stimulated rhizome induction, while other plant hormones were inactive. The (R)-isomers of the 1, 3, 5-triazine compounds also stimulated induction of the rhizomes, whereas the (S)-isomers did not. The described rhizome induction system seems to be suitable as a cytokinin bioassay. The (R)-1, 3, 5-triazine compounds showing rhizome-inducing activity (RI activity) inhibited root formation and plant growth at high concentrations with symptoms which were very similar to those of BA. Therefore, the (R)-isomers appear to act as cytokinins in the rhizome induction assay.     

The efficacy of a petroleum spray oil against Aphis gossypii Glover on cotton. Part 1: mortality rates and sources of variation

Petroleum spray oils (PSOs) kill insect pests on contact, and the composition of modern PSOs is substantially different from the ones introduced earlier. The effects of direct application of a new nC24 PSO on the cotton aphid, Aphis gossypii Glover, were therefore determined. This covered not only aphid mortality rates but also the way in which the oils affected aphid behaviour at the time of contact with the oil. Direct application of the nC24 oil proved to be highly effective in controlling A. gossypii at a range of concentrations between 1 and 10% v/v. The oil killed cotton aphids quickly, with most of the mortality occurring within the first 10 min of spraying. The fast killing action of the oils prevented any behavioural responses by the aphids. Aphids killed by the oils became flaccid and their legs and antennae extended horizontally relative to the body axis. With time, their cuticle became very shiny and began to darken. The quick death of the aphids suggested a contact mode of action of the oils, an interpretation supported by the lack of any negative effect on aphids not initially reached by the oils. However, those aphids not hit by the oils, but that subsequently encountered oil-treated areas when they moved elsewhere, also died, indicating that the oil deposits are also toxic to the aphids. The mode of action of the oil thus seems to be versatile, and the means by which it kills the aphids may be more complex than anoxia, which is the widely claimed mechanism attributed to PSOs. This oil now needs to be tested for any possible indirect effects on the cotton aphid (e.g. through its host-plant acceptance behaviour). The implications of the present findings for cotton aphid control and assessment of PSO efficacy in the field are discussed.     

含1,3,4-噻二唑的吡啶联吡唑乙酰胺类化合物的合成及除草活性

以乙酰丙酮、溴乙酸乙酯和2,6-二氯吡啶为起始原料,经取代、肼基化、环合、水解、酸化及缩合等反应,得到9个未见文献报道的吡啶联吡唑乙酰基类化合物 B1~B9 。其结构均经核磁共振氢谱和质谱表征。初步生物活性测定表明:在150 g/hm2的处理剂量下,大部分目标化合物表现出一定的除草活性,其中化合物 B2、B3、B6 和 B8 对苘麻Abutilon theophrasti Medicus、反枝苋Amaranthus retroflexus和凹头苋Amaranthus lividus L.生长的抑制率接近100%。     

Synthesis,insecticidal and acaricidal properties of some 5-alkoxy-, 5-alkylthio-6-oxo-1-phenyl-1H-pyridazin-4-yl and 6-oxo-5-phenoxy-1-phenyl-1H-pyridazinyl phosphorus esters. II

A series of novel 5-alkoxy-, 5-alkylthio-6-oxo-1-phenyl-1H-pyridazin-4-yl and 6-oxo-5-phenoxy-1-phenyl-1H-pyridazin-4-yl phosphorus esters was prepared from the corresponding alkali pyridazin-4-olates and their insecticidal and acaricidal activities studied. Many of the compounds, especially the diethyl and dimethyl phosphates and OO-diethyl and OO-dimethyl phosphorothioates, showed high insecticidal and acaricidal activity.     

Quantitative structure-activity studies of substituted benzyl chrysanthemates: 5. Physicochemical substituent factors and neurophysiological effects in knockdown and lethal activities against the house fly

Knockdown and lethal activities of meta- and para-substituted benzyl (1R)-trans-chrysanthemates against the house fly were measured under synergistic conditions using piperonyl butoxide as an inhibitor of oxidative metabolism and NIA 16388 as an inhibitor of hydrolytic degradation. The variations in these activities were quantitatively analyzed in terms of physicochemical substituent effects using electronic, hydrophobic, and steric parameters of the aromatic substituents, and regression analysis. The most significant parameter in determining these activities is the steric bulkiness represented by the van der Waals voluem, the effect of which is highly specific to substituent positions. The substituent effects on knockdown and lethal activities against the house fly are shown to correspond well, respectively, with those on the convulsive and lethal activities against the American cockroach. The relationship between these symptomatic activities against the house fly and the neurophysiological activities determined by using excised nerve cords from American cockroaches were also quantitatively analyzed. Each house fly symptomatic activity was found to be analyzable by a linear combination of the neuroexcitatory and neuroblocking activity indices when the transport factor was separated by using the hydrophobicity parameter.