Photochemical transformation of thiophanate-methyl and thiophanate to alkyl benzimidazol-2-yl carbamates

The systemic fungicides thiophanate-methyl (TPM) and thiophanate (TPE) were transformed in aqueous solutions on glass by irradiation with u.v. and sunlight to the more effective fungitoxic substances methyl benzimidazol-2-yl carbamate (MBC) and ethyl benzimidazol-2-yl carbamate (EBC), respectively. The thiophanate fungicides were not converted when incubated in the dark. The photochemical transformation of TPM and TPE to the corresponding alkyl benzimidazol-2-yl carbamates increased with the exposure time of u.v. irradiation. However, no light catalysed reactions occurred when both fungicides were irradiated with u.v. light in the solid state. The residue of TPM and TPE on leaves of cotton plants following spray application were transformed by the energy of sunlight to the more fungitoxic MBC and EBC.     

The rodenticidal activity of reserpine and related compounds

The spread of warfarin resistant mice in the early 1970s prompted an urgent search for alternative rodenticides suitable for commercial use. The early success of a stupefying compound, chloralose (alphachloralose), directed research in that direction and led ultimately to the adoption of reserpine as a rodenticide. Laboratory and field trials of reserpine, and some of its naturally occurring and synthetic analogues, against mice and rats, are reported here.     

新型含1,2,4-噻二唑环的甲氧丙烯酸酯类化合物的合成及抑菌活性

设计合成了14个含1,2,4-噻二唑环的甲氧丙烯酸酯类新化合物,其结构经红外、电喷雾串联质谱(ESI-MS)和核磁共振氢谱确证。生物活性测定结果表明,化合物 7j、7k、7m、7n 在 100 mg/L质量浓度下对小麦赤霉病菌等6种供试病原菌均有较高抑菌活性, 其中7i 对小麦赤霉病菌Fusarium graminearum的抑菌率为100%。     

Studies on pesticides based on coumarin. III. Synthesis and antifungal activity of substituted 4-methyl-coumarins and related compounds

A series of substituted 4-methylcoumarins was synthesised and the members tested for their toxicity towards mycelial growth of seven phytopathogenic fungi in culture. Rhizoctonia solani, Alternaria alternata and Fusarium solani exhibited maximum sensitivity to these compounds whereas Pythium aphanidermatum, Colletotrichum falcatum, Drechslera oryzae and Macrophomina phaseolina were relatively less sensitive. 6-Ethyl-3-n- propyl-7-hydroxy4-methylcoumarin ( I ) was relatively toxic towards all fungi except C. falcatum, P. aphanidermatum and M. phaseolina. The 6-n-butyl ( III ) and 6-(1, 1, 3, 3-tetramethylbutyl) ( VI ) derivatives were highly toxic to R. solani with EC₅₀, values of lμg ml^?1.     

Impedimetric evaluation of compounds for antifungal activity versus Aspergillus niger

The procedure described utilized a microbial monitoring system (bactometer) to measure impedimetrically the inhibitory activity of known antifungal compounds (2-(thiocyanomethylthio)benzothiazole [TCMTB], 3-iodo-2-propynylbutyl carbamate [IPBC], chlorothalonil, tebuconazole, and copper-8-quinolinolate [Cu-8]) on growth of Aspergillus niger Teigh. in a liquid medium. The MIC values determined were based on the activity of the compounds to inhibit a change in the capacitance of the medium during a 96-h period after inoculation. The MIC values obtained with the bactometer were compared with MIC values derived from the inhibition of radial growth of A. niger on the same liquid medium solidified with agar. The MIC values for all the compounds tested were substantially lower when determined with the bactometer than on agar. The impedimetric evaluation of compounds for antifungal activity offers advantages of speed, sensitivity, and data collection.     

新型含2(1H)-喹啉酮的甲氧基丙烯酸酯类

以(E)-2-[2'-(bromo-methyl)phenyl]3-甲氧基丙烯酸甲酯和2(1H)-喹啉酮类化合物为原料,通过醚化等反应,合成了11个新型含2(1H)-喹啉酮结构的甲氧基丙烯酸酯类化合物,其结构经红外、电喷雾串联质谱(ESI-MS)和核磁共振氢谱确证。初步生物活性测试结果表明:在100 mg/L质量浓度下,部分目标化合物对烟草赤星病菌Alternaria alternata等6种病原菌具有一定的抑菌活性,其中5a对水稻稻瘟病菌Pyricularia grisea的抑菌率达100%。     

The pyrethrins and related compounds. Part XXV: Synthesis and insecticidal activity of conformationally restrained compounds related to 3-phenoxybenzyl esters

Derivatives of 3-phenoxybenzyl pyrethroidal esters were synthesised in which rotation about the benzylic C-1–C-α bond was restricted by an additional bridging ring. The insecticidal activities of these compounds to houseflies (Musca dornestica) and mustard beetles (Phaedon cochleariae) depended on the size of the bridging unit and on whether it joined C-α to C-2 or C-6 of the benzyl nucleus. The results obtained are considered in relation to current correlations of the structures with the activities of pyrethroids.     

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.     

2-取代苯并咪唑类化合物的合成及其抑菌活性

以甲基酮、草酸二乙酯或草酸二甲酯、盐酸羟胺和水合肼为原料,通过缩合、环合、水解等反应,将取代吡唑环、异 NFDA1 唑环引入苯并咪唑的2位,设计合成了13个未见文献报道的2-取代苯并咪唑类衍生物,其结构经红外、电喷雾串联质谱(ESI-MS)和核磁共振氢谱确证。初步生物活性测试结果表明,在100 mg/L质量浓度下,所有目标化合物对6种供试病原菌均具有一定的抑菌活性,其中2-吡唑取代的化合物 2a~2d 对苹果炭疽病菌Glomerella cingulata的抑制率在80%以上,2-异 NFDA1 唑取代的化合物 4a 对番茄早疫病菌 Alternaria solani 、苹果炭疽病菌和水稻稻瘟病菌 Magnaport hegrisease 的抑制率达100%。     

The pyrethrins and related compounds. Part XXXIV. Optimisation of insecticidal activity in non-esters

Optimisation of activity within the structural constraints defined by the preceding work, by varying the substituents on phenyl in the acid fragment (10 variations), the nature of the group fulfilling the dimethyl function (three variations), the central linking group (four variations) and the presence or absence of a 4-fluoro substituent in the alcohol fragment, has led to achiral compounds as active as bioresmethrin against houseflies and mustard beetles. Statistical analysis of the effects has shown that particular combinations, for instance the cyclopropyl form of dimethyl with a central E-alkene group (but not a central ether group), lead to higher activity than expected. 4-Fluoro substitution enhances activity more strongly against mustard beetles. Difluorocyclopropyl compounds are on average slightly more active than cyclopropyl analogues.     

Fungicidal activity of 2-(1-alkenyl)-3-hydroxy-1,4-naphthoquinones and related compounds

The fungicidal activity of a series of 2-(1-alkenyl)-3-hydroxy-1,4-naphthoquinones and their acetates has been assessed against various fungi in vitro and against others, notably powdery mildews, in vivo, and the activity compared with that of analogous compounds bearing saturated side chains. Several of the compounds demonstrated a broad spectrum of activity in vitro. Whereas the presence of α-unsaturation in the side chain is essential for the in-vitro activity against the non-obligate fungi tested, it is of virtually no importance for the curative effect against Erysiphe graminis on barley. Only the corresponding acetates had activity against the latter pathogen.     

Antimitotic activity of methyl benzimidazol-2-yl carbamate (MBC) in Aspergillus nidulans

Mitosis in germ tubes of Aspergillus nidulans was inhibited directly upon addition of methyl benzimidazol-2-yl carbamate to liquid cultures, whereas dry weight increase and DNA and RNA synthesis were progressively inhibited only after a few hours. Microscopic observation of the organism, grown on malt extract agar containing MBC revealed abnormal chromatin configurations. The possible mode of action of MBC through interference with spindle formation is discussed.     

氯康唑类似物的合成及抑菌活性

为了发现更多抑菌活性优于抗菌药物盐酸氯康唑的化合物,在盐酸氯康唑的结构基础上,设计、合成了其类似物,并进行了抑菌活性测定。以芝麻酚为原料,经过酰化、1,2,4-三氮唑基团的引入以及醚化3步反应,合成了19个新型氯康唑类似物4a~4s。所有目标化合物的结构均经过1H NMR、13C NMR和ESI-MS等确认。采用抑制菌丝生长速率法测定了目标化合物对水稻稻瘟病菌、番茄早疫病菌、马铃薯干腐病菌、玉米弯孢病菌、烟草赤星病菌、小麦赤霉病菌和棉花枯萎病菌7种植物源病原真菌的抑制活性,并进一步测定了部分化合物的EC50值。结果显示,在50 μg/mL时,大多数目标化合物对供试菌株表现出不同程度的抑制作用。其中,化合物4d和4m对番茄早疫病菌的EC50值分别为6.28和4.61 μg/mL,4m对烟草赤星病菌的EC50值3.58 μg/mL,与对照药剂腈菌唑（对番茄早疫病菌和烟草赤星病菌的EC50值分别为1.63和1.05 μg/mL）在同一数量级,具有开发为新型抗菌药物的潜能。     

桧木醇衍生物的合成及抑菌活性

桧木醇是具有?酚酮骨架的单萜类天然化合物, 设计并合成了17个新型桧木醇衍生物, 其结构经核磁共振波谱及高分辨质谱分析确证。抑菌活性测定结果表明,目标化合物在50 μg/mL下对水稻纹枯病菌Rhizoctonia solani、番茄灰霉病菌Botrytis cinerea、油菜菌核病菌Sclerotinia sclerotiorum、苹果树腐烂病菌Valsa mali和黄瓜炭疽病菌Colletotrichum orbiculare均表现出较好的抑菌活性,其中化合物 3a 对水稻纹枯病菌、 3j 对番茄灰霉病菌、 3m 对油菜菌核病菌的EC₅₀值分别为1.84、2.47和1.05 μg/mL,表现出比桧木醇 (2.00、11.3和5.40 μg/mL) 更优的活性。     

Insecticidal activity of the pyrethrins and related compounds VIII. Relation of polarity with activity in pyrethroids

Comparing insecticidal activities of a wide range of pyrethroids with polarities measured by reversed phase, thin-layer chromatography suggests that there are optimum polarities for potency in both Musca domestica and Phaedon cochleariae, and that these optima have closely similar values. The significance of these conclusions is discussed.     

基于组效关系的土荆芥挥发油熏蒸抑菌活性组分鉴定

通过分析土荆芥Chenopodium ambrosioides L.挥发油对灰葡萄孢Botrytis cinerea Pers.的熏蒸抑制作用与其化学组分之间的组效关系,鉴定挥发油中与抑菌作用显著相关的活性成分。采用气相色谱-质谱联用(gas chromatograph-mass spectrometry, GC-MS)技术分析29个土荆芥挥发油样品的化学组分和相对含量,同时以菌丝生长速率法分别测定各样品对灰葡萄孢的熏蒸抑制效能。在此基础上,我们选取相对含量占总挥发油91.39%～99.50%的13种共有化合物为特征化合物,采用正交最小偏二乘判别分析(orthogonal partial least squares discriminant analysis, OPLS-DA)法分析组效关系,同时利用双变量相关分析验证组效分析结果。结果表明,3-甲基-4-异丙基苯酚、麝香草酚、α-萜品烯、p-伞花烃和驱蛔萜等化合物是土荆芥挥发油对灰葡萄孢菌发挥熏蒸抑制作用的主要活性组分。     

Insecticidal activity of the pyrethrins and related compounds IV.—Essential features for insecticidal activity in chrysanthemates and related cyclopropane esters

A range of 5-benzyl-3-furylmethyl cyclopropane carboxylates and other esters are evaluated against house-flies, mustard beetles and two mosquito species. The results show the importance for activity of a gem-dimethyl group on the cyclopropane ring and that substitutions at C₃ give wide variations in insecticidal activity and marked species specificity. Some of the compounds had considerable knockdown activity against houseflies, but the structural requirements for this type of action differ markedly from those for kill.     

Methyl benzimidazol-2-ylcarbamate,the fungitoxic principle of thiophanate-methyl

A correlation was found between the formation of benzimidazol-2-ylcarbamate esters from the thiophanate fungicides [thiophanate, thiophanate-methyl and 2-(3-methoxycarbonylthioureido)aniline] and the fungitoxie activity of these fungicides. Fungitoxic activity of the thiophanates is increased by ageing in aqueous media while fungitoxicity as well as conversion rate decrease at lower pH. It is concluded that it is not the thiophanates themselves but the corresponding benzimidazol-2-ylcarbamate esters that are responsible for the fungitoxic effect. Hence thiophanate-methyl, like benomyl, is a precursor of the fungitoxic agent methyl benzimidazol-2-ylcarbamate (MBC). Indications were obtained that fungal metabolic activity can increase the rate of conversion of thiophanate-methyl into MBC.     

The incorporation of DDT and related compounds into lecithin bilayers

The incorporation of DDT and several analogs into the hydrophobic interior of lecithin bilayers has been monitored by observing the nuclear magnetic resonance spectra of the aromatic ring protons. A fluid bilayer interior was obligatory for the incorporation of the chemicals. The amount of the different compounds which can be taken up into the lipid in aqueous media varies significantly, and this difference is not related to the organic: aqueous partition coefficients of the analogs. The amount of DDT, the most nonpolar of the compounds studied, which could be incorporated into the bilayers was much lower than the levels of other, more water-soluble analogs.     

The pyrethrins and related compounds. Part XXVII. Esters of pulegenic and related acids

A report by Staudinger and Ruzicka of the insecticidal activity of an ester of pulegenic acid with mixed naturally derived alcohols had not been examined further, and had been misinterpreted in a review. Therefore, two isomeric pulegenic and nine related acids were synthesised, characterised and esterified with modern, more effective, pyrethroidal alcohols. The pulegenic esters were inactive, but low activity was found in esters of acids in which the 5-membered ring was additional to, rather than a replacement for, the cyclopropane ring.