Insecticidal and fungicidal activity of new synthesized chitosan derivatives

Chitosan, the N-deacetylated derivative of chitin, is a potential biopolysaccharide owing to its specific structure and properties. In this paper, we report on the synthesis of 24 new chitosan derivatives, N-alkyl chitosans (NAC) and N-benzyl chitosans (NBC), that are soluble in dilute aqueous acetic acid. The different derivatives were synthesized by reductive amination and analyzed by 1H NMR spectroscopy. A high degree of substitution (DS) was obtained with N-(butyl)chitosan (DS 0.36) at a 1:1 mole ratio for NAC derivatives and N-(2,4-dichlorobenzyl)chitosan (DS 0.52) for NBC derivatives. Their insecticidal and fungicidal activities were tested against larvae of the cotton leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae), the grey mould Botrytis cinerea Pers (Leotiales: Sclerotiniaceae) and the rice leaf blast Pyricularia grisea Cavara (Teleomorph: Magnaporthe grisea (Hebert) Barr). The oral feeding bioassay indicated that all the derivatives had significant insecticidal activity at 5 g kg(-1) in artificial diet. The most active was N-(2-chloro-6-fluorobenzyl)chitosan, which caused 100% mortality at 0.625 g kg(-1), with an estimated LC50 of 0.32 g kg(-1). Treated larvae ceased feeding after 2-3 days; the mechanism of action remains unknown. In a radial hyphal growth bioassay with both plant pathogens, all derivatives showed a higher fungicidal action than chitosan. N-Dodecylchitosan, N-(p-isopropylbenzyl)chitosan and N-(2,6-dichlorobenzyl)chitosan were the most active against B cinerea, with EC50 values of 0.57, 0.57 and 0.52 g litre(-1), respectively. Against P grisea, N-(m-nitrobenzyl)chitosan was the most active, with 77% inhibition at 5 g litre(-1). The effect of different substitutions is discussed in relation to insecticidal and fungicidal activity.     

含1,2,4-三唑基和肟醚基的N-甲氧基氨基甲酸酯类化合物的合成及杀菌活性

通过(Z)-1-(取代苯基)-2-(1H-1,2,4-三唑-1-基)乙酮肟与N-甲氧基-N-(2-溴甲基苯基)氨基甲酸甲酯反应,合成了11个新的含有三唑基和肟醚基的N-甲氧基氨基甲酸酯类化合物( V1 ~ V11 ),其结构均经1H NMR、IR、LC/MS及元素分析确证。对合成的化合物进行了离体抑菌活性实验,结果表明:在50 mg/L下,所有化合物对小麦赤霉病菌Gibberella zeae (Schw.)Petch、稻瘟病菌Pyricularia oryzae Cav.和黄瓜灰霉病菌Botrytis cinerea Pers.都有一定的抑菌活性,其中 V4 、 V11 对稻瘟病菌的抑菌活性分别达96.5%和96.7%,对黄瓜灰霉病菌的抑菌活性分别达到95.9%和90%。     

含氟2-氧代环己基磺酰胺的合成及杀菌活性

以环己酮为原料,经磺酰化、碱化后得到2-氧代环己基磺酸钾盐,再经生成酰氯后与胺反应得到9个新的标题化合物,其结构经1H NMR、13C NMR和元素分析确证。初步的生物测定结果表明,部分化合物具有一定的杀菌活性,其中 3e 对棉花立枯病菌Rhizoctonia solani和黄瓜灰霉病菌Botrytis cinerea、 3h和3i 对黄瓜灰霉病菌和油菜菌核病菌Sclerotinia sclerotiorum有较好的活性,50 μ g/mL下的抑制率均在90％以上。     

昆虫病原线虫共生菌YL001细胞内代谢产物 抑菌作用研究初报

以生物活性跟踪法测定了菌株代号为YL001的昆虫病原线虫共生菌Xenorhabdus nematophilus细胞内代谢产物的不同溶剂提取物及其不同馏分的抑菌活性。结果表明,YL001细胞内代谢产物的乙醇提取物和甲醇提取物的抑菌活性均高于石油醚提取物、乙酸乙酯提取物和正丁醇提取物,前两种提取物对番茄灰霉病菌Botrytis cinerea和辣椒疫霉病菌Phytophthora capsici的72 h菌丝生长抑制作用最强,在0.4 mol/mL浓度时抑制率均达100％。乙醇提取物经硅胶柱层析分离,洗出液合并后收集得到8个馏分。测定了各馏分对番茄灰霉病菌菌丝生长的抑制作用,结果表明:馏分F6的抑菌活性最高,在0.5 mol/mL浓度时,96 h的菌丝生长抑制率可达96.09%;提取物的活性段主要集中在馏分F6、F7和F8。活体组织法测定结果表明,其乙醇提取物在10 mg/mL的剂量下对番茄灰霉病的保护效果为64.81%,治疗效果为62.03%。     

Dehydro-alpha-lapachone isolated from Catalpa ovata stems: activity against plant pathogenic fungi

The methanol extract of stems of Catalpa ovata G Don exhibits potent in vivo antifungal activity against Magnaporthe grisea (Hebert) Barr (rice blast) on rice plants, Botrytis cinerea Pers ex Fr (tomato grey mould) and Phytophthora infestans (Mont) de Bary (tomato late blight) on tomato plants, Puccinia recondita Rob ex Desm (wheat leaf rust) on wheat plants and Blumeria graminis (DC) Speer f. sp. hordei Marchal (barley powdery mildew) on barley plants. An antifungal substance was isolated and identified as dehydro-alpha-lapachone from mass and nuclear magnetic resonance spectral data. It completely inhibited the mycelial growth of B. cinerea, Colletotrichum acutatum Simmonds, Colletotrichum gloeosporioides Simmonds, M. grisea and Pythium ultimum Trow over a range of 0.4-33.3 mg litre(-1). It also controlled the development of rice blast, tomato late blight, wheat leaf rust, barley powdery mildew and red pepper anthracnose (Colletotrichum coccodes (Wallr) S Hughes). The chemical was particularly effective in suppressing red pepper anthracnose by 95% at a concentration of 125 mg litre(-1).     

Screening extracts of Achyranthes japonica and Rumex crispus for activity against various plant pathogenic fungi and control of powdery mildew

Methanol extracts of fresh materials of 183 plants were screened for in vivo antifungal activity against Magnaporthe grisea, Corticium sasaki, Botrytis cinerea, Phytophthora infestans, Puccinia recondita and Erysiphe graminis f sp hordei. Among them, 33 plant extracts showed disease-control efficacy of more than 90% against at least one of six plant diseases. The methanol extracts of Achyranthes japonica (whole plant) and Rumex crispus (roots) at concentrations greater than 11 g fresh weight of plant tissue per litre of aqueous Tween 20 solution effectively controlled the development of barley powdery mildew caused by E graminis f sp hordei in an in vivo assay using plant seedlings. At a concentration of 300 g fresh weight of plant tissue per litre of Tween 20 solution, the two extracts were as efficient as the fungicide fenarimol (30 mg litre(-1)) and more active than the fungicide polyoxin B (100 and 33 mg litre(-1)) against Sphaerotheca fuliginea on cucumber plants in glasshouse trials.     

1,2,3-噻二唑联-1,2,4-三唑衍生物的合成及抑菌活性

以4-氨基-3-(4-甲基-1,2,3-噻二唑)-1,2,4-三唑-5-硫酮为原料,与醛在冰乙酸中回流制得15个新型4-取代亚氨基-3-(4-甲基-1,2,3-噻二唑)-1,2,4-三唑-5-硫酮化合物,其结构经IR、1H NMR 及元素分析表征,其中,化合物 5c 的结构经单晶测试确证,该晶体属单斜晶系,P2(1)/c空间群,晶胞参数a=1.403 7(3) nm,b=1.570 5(3) nm,c=0.686 4(14) nm,β=102.06(3)°,V = 1.479 8(5) nm3,Z=4,F(000)=656。初步的抑菌活性测试结果表明;所有化合物对黄瓜灰霉病菌Botrytis cinerea都有较好的抑制作用,化合物 5l 的抑制率达87%, 5c、5d和5f 的抑制率在78%左右; 5a 对小麦赤霉病菌Gibberella zeae的抑制率为78.7%; 5m 对西瓜炭疽病菌Colletotrichum lagenarium的抑制率为65.6%。     

南欧丹参花提取物杀菌活性初步研究

采用系统溶剂对南欧丹参Salvia sclarea L.花进行提取,以孢子萌发试验法、抑制菌丝生长速率法和盆栽试验系统测定了粗提物对植物病原真菌的生物活性。结果表明,石油醚为提取南欧丹参花活性成分的最佳溶剂。石油醚提取物在离体条件下能显著抑制多种供试真菌菌丝的生长,其对番茄灰霉病菌Botrytis cinerea的EC50值为77.20 μg/mL;对盆栽小麦白粉病Erysiphe graminis的防护效果为94.94%,治疗效果为84.21%。     

Acidic derivatives of the fungicide fenpiclonil: effect of adding a methyl group to the N-substituted chain on systemicity and fungicidal activity

A new acidic derivative of the fungicide fenpiclonil was synthesized containing a methyl group on the alpha-position of the carboxyl function of N-carboxymethyl-3-cyano-4-(2,3-dichlorophenyl)pyrrole. The phloem mobility of the resulting N-(1-carboxyethyl)-3-cyano-4-(2,3-dichlorophenyl)pyrrole was comparable with that of the former compound, but was higher at external pH 5.0. Unlike the derivatives previously synthesized, it was comparable with fenpiclonil in its fungicidal activity against the pathogenic fungus Eutypa lata.     

曲酸及氯曲酸衍生物的合成及抑菌活性

以曲酸为原料,设计合成了16个曲酸衍生物(QI-01~QI-16)和10个氯曲酸衍生物(QII-01~QII-10),通过核磁共振氢谱及元素分析对其结构进行了表征。初步抑菌活性测定结果表明:所有供试化合物对苹果炭疽病菌Glomerella cingulata和番茄灰霉病菌Botrytis cinerea的菌丝生长均有不同程度的抑制作用,其中化合物QI-07和QI-11对苹果炭疽病菌活性最高,50μg/mL时的抑制率分别为79.3%和86.2%;化合物QII-04、QII-08和QII-09对番茄灰霉病菌活性最高,50μg/mL时的抑制率分别为70.0%、70.0%和76.7%。     

N-取代苯基-4-(1-甲基-1H-吡唑-5-基)噻吩-2-甲酰胺的合成、杀菌活性及分子对接

为了寻找结构新颖的琥珀酸脱氢酶 (SDH) 类衍生物,在前期发现吡唑联苯甲酰胺基础上,采用骨架跃迁的策略,设计并合成了18个N-取代苯基-4-(1-甲基-1H-吡唑-5-基) 噻吩-2-甲酰胺类衍生物 ( 3a~3n , 4a ~ 4d ),其中17个为新化合物。通过 1H NMR、13C NMR 和高分辨质谱 (HRMS) 确证了化合物的结构。离体杀菌活性测试结果表明:部分化合物对小麦赤霉病菌Fusarium graminearum、马铃薯早疫病菌Alternaria solani和草莓灰霉病菌 Botrytis cinerea 显示出较好的杀菌活性,其中化合物 3k 和 4d 对小麦赤霉病菌的EC₅₀值分别为18.5和14.3 mg/L,化合物 4d 对马铃薯早疫病菌的EC₅₀值为15.7 mg/L,活性略高于对照药剂噻呋酰胺 (EC₅₀值27.8 mg/L),化合物 3k 和 3m 对草莓灰霉病菌的EC₅₀值分别为15.3和 9.9 mg/L,与噻呋酰胺活性 (EC₅₀值10.4 mg/L) 相当。分子对接研究结果显示:具有较高活性的化合物N-(4-氟苯基乙基)-4-(1-甲基-1H-吡唑-5-基) 噻吩-2-甲酰胺 ( 3m ) 与靶酶 (SDH) 的氨基酸残基之间存在较强的氢键作用。     

N-烃氧羰基-2-噻唑烷酮衍生物的合成及其杀菌活性

为了寻求新的杀菌先导化合物,通过2-噻唑烷酮与氯甲酸酯的缩合反应得到11个N-烃氧羰基-2-噻唑烷酮衍生物( 5a ~5k), 其中10个为新化合物,其结构均经1H NMR、MS、IR和元素分析表征。初步离体杀菌实验结果表明,大多数化合物较之母体2-噻唑烷酮具有更高的杀菌活性。在浓度为2 000 mg/L下,化合物 5c、5d、5e、5f、5g、5h、5i、5j 对油菜菌核病菌Sclerotinia sclerotiorum的抑制率为100%, 5i 对番茄灰霉病菌Botrytis cinerea、柑桔青霉病菌Penicillium italicum和油菜菌核病菌的抑制率均为100%。     

(E)-α-氧代环十二酮肟醚的合成及其杀菌活性

由环十二酮先后经肟化和醚化反应合成了一系列(E)-α-氧代环十二酮肟醚,收率59%~92%。其结构经IR,1H NMR,13C NMR确证。以化合物5o为代表,通过单晶X-衍射分析确证了其构型为E式。生物测定结果表明,多数化合物对蔬菜苗期立枯病菌、黄瓜黑星病菌、黄瓜炭疽病菌、瓜类灰霉病菌,棉花枯萎病菌和芦笋茎枯病菌的生长有良好的抑制活性。如5k对上述6种病原菌的EC50值分别为13、9、12、19、14、3mg/L。     

苯甲酰基甲磺酰胺的合成与杀菌活性

以苯乙酮为原料,用三氧化硫·二氧六环进行磺化,经碱中和后制备得到苯甲酰甲磺酸盐;与草酰氯在DMF为催化剂的条件下反应生成磺酰氯,再与胺反应,制备得到14个苯甲酰基甲磺酰胺,其中13个为新化合物。其结构通过1H NMR、IR和元素分析确证。在50 μg/mL浓度时,该系列化合物对番茄灰霉病菌Botrytis cinerea、小麦赤霉病菌Gibberlla zeae、水稻纹枯病菌Rhizoctonia solani、梨黑星病菌Venturia nashicola菌丝生长均具有很好的抑制活性,其中化合物 B-8、B-9、B-10、B-12 对番茄灰霉病菌的EC50值分别为1.0、0.2、1.2、0.4 μg/mL,接近或优于对照药剂嘧霉胺, B-8、B-10、B-11 对小麦赤霉病菌的EC50值分别为0.07、0.2、0.05 μg/mL,优于对照药剂多菌灵。     

Activity of the Antifungal Protein from Aspergillus giganteus Against Botrytis cinerea

ABSTRACT Botrytis blight (gray mold), caused by Botrytis cinerea, is one of the most widely distributed diseases of ornamental plants. In geranium plants, gray mold is responsible for important losses in production. The mold Aspergillus giganteus is known to produce and secrete a basic low-molecular-weight protein, the antifungal protein (AFP). Here, the antifungal properties of the Aspergillus AFP against various B. cinerea isolates obtained from naturally infected geranium plants were investigated. AFP strongly inhibited mycelial growth as well as conidial germination of B. cinerea. Microscopic observations of fungal cultures treated with AFP revealed reduced hyphal elongation and swollen hyphal tips. Washout experiments in which B. cinerea was incubated with AFP for different periods of time and then washed away revealed a fungicidal activity of AFP. Application of AFP on geranium plants protected leaves against Botrytis infection. Cecropin A also was active against this pathogen. An additive effect against the fungus was observed when AFP was combined with cecropin A. These results are discussed in relation to the potential of the afp gene to enhance crop protection against B. cinerea diseases.     

N-(2,4,5-三氯苯基)-2-氧代环己烷基磺酰胺对灰葡萄孢的抑制作用

研究了新型环烷基磺酰胺类化合物N-(2,4,5-三氯苯基)-2-氧代环己烷基磺酰胺(简称化合物108)对灰葡萄孢菌丝生长、孢子形成和萌发以及菌核产生等不同生育阶段的抑制作用及其对菌丝致病力和形态结构的影响。结果表明:化合物108对灰葡萄孢菌丝生长和孢子形成及孢子萌发具有明显的抑制作用,其EC50值分别为6.90、4.70和4.11μg/mL;菌核形成受到明显抑制,当药剂质量浓度达20μg/mL时,无菌核产生。经化合物108处理后的灰葡萄孢菌丝致病力下降,40μg/mL处理的菌丝致病力显著低于对照。超微结构观察结果表明,化合物108能导致灰葡萄孢菌丝萎缩、塌陷和变形,菌体细胞壁增厚、皱缩及分层。     

含嘧啶环的N-甲氧基氨基甲酸甲酯类化合物 的合成及生物活性

为了寻找高效、低毒的新农药,采用活性结构拼接法设计合成了9个新的含嘧啶环的N-甲氧基氨基甲酸甲酯类化合物( 4a~4i ),其结构经IR、1H NMR、LC/MS和元素分析确证。生物活性测定结果表明,部分化合物在50 mg/L下对小麦赤霉病菌Gibberella zeae、稻瘟病菌Pyricularia oryzae 和灰霉病菌Botrytis cinerea有较好的抑菌活性,其中 4b、4i 对小麦赤霉病菌的抑制率分别为90.9%和82.6%, 4c、4f 对稻瘟病菌的抑制率分别为86.8%和80.0%。     

Development of novel pesticides based on phytoalexins: Part 2. Quantitative structure-activity relationships of 2-heteroaryl-4-chromanone derivatives

Phytoalexins are low-molecular-weight chemicals that immune systems of plants produce and accumulate in response to infections, especially those of fungal origin. Although their content is not high in plants, yet they have shown unique fungicidal activity and played an important role in the defence system of plants. In searching for novel environmentally benign fungicides with high activity, the structures of flavanone derivatives, one of the most important phytoalexins groups, have been modified via bioisosteric substitution and a series of 2-heteroaryl-4-chromanones were designed and synthesized. They showed good fungicidal activities against rice blast disease, Pyricularia grisea (Sacc). Their IC50 values were tested in vitro and the relationship between structure and fungicidal activity was analyzed quantitatively using a Hansch-Fujita approach. The results showed that hydrophobicity was very important for fungicidal activity and there is apparently an optimum hydrophobic property for the molecules at a log Pow value of about 2.7. In addition, the results indicated that electronic effects played an important role in binding with the receptor and that the C=O group was probably a electron-accepting site. The quantitative structure-retention correlative equation of the title compounds was also established.     

7种植物精油对番茄灰霉病的抑制效果

以番茄灰霉病菌为供试对象,系统测试了香茅油、柠檬草油、樟油、黄樟油、天然冬青油、山苍子油、肉桂油等7种植物精油的抑菌效果。结果表明:7种精油中,樟油和肉桂油对番茄灰霉病的抑制效果较好。离体活性测试中,樟油和肉桂油对番茄灰霉病菌菌丝生长抑制作用的EC50分别为126.6205mg/L和128.1587mg/L,对孢子萌发的EC₅₀分别为181.8763mg/L和228.5453mg/L;活体组织法测试表明,2种精油对番茄灰霉病具有较好的保护效果,在500mg/L浓度下,黄瓜子叶法防效均达100%,果实针刺法防效分别为52.42%和50.48%;盆栽试验表明两者在2000mg/L时,对番茄灰霉病的防效分别为59.65%和61.40%。     

取代苯甲酸酯类化合物的合成与杀菌活性

以取代苯甲酸和异戊醇为原料,合成了14个未见文献报道的取代苯甲酸酯类化合物,其结构均通过红外光谱、核磁共振氢谱和气相色谱-质谱联用（GC-MS）确证。生物活性测定结果表明:14个新化合物对灰霉病菌Botrytis cinerea、稻瘟病菌Piricularia oryzae和纹枯病菌Rhizoctonia solani的活体杀菌活性均好于离体杀菌活性,尤其是化合物3j在500 μg/mL下对黄瓜灰霉病的活体防效达96.4%,3e（500 μg/mL）对水稻稻瘟病的活体防效为96.3%。