Synthesis of novel azabicyclo derivatives containing a thiazole moiety and their biological activity against pine-wood nematodes

Abstract

To explore a new skeleton with nematicidal activity, a series of novel azabicyclo derivatives containing a thiazole moiety were designed, synthesized and evaluated for their nematicidal activities. The bioassay results against pine-wood nematodes (Bursaphelenchus xylophilus) showed that most of the title compounds displayed nematicidal activity at a concentration of 40?mg/L. Especially, the title compounds2-((8-methyl-8-azabicyclo[3.2.1]octan-3-yl)oxy)-4-(4-chlorophenyl)thiazole (7e), 2-((8-methyl-8-azabicyclo[3.2.1]octan-3-yl)thio)-4-phenylthiazole (10a) and 2-((8-methyl-8-azabicyclo [3.2.1]octan-3-yl)thio)-4-(4-chlorophenyl)thiazole (10e) exhibited more than 90% mortality against Bursaphelenchus xylophilus.     

Volatile Organic Compounds from Bacillus aryabhattai MCCC 1K02966 with Multiple Modes against Meloidogyne incognita

Plant-parasitic nematodes cause severe losses to crop production and economies all over the world. Bacillus aryabhattai MCCC 1K02966, a deep-sea bacterium, was obtained from the Southwest Indian Ocean and showed nematicidal and fumigant activities against Meloidogyne incognita in vitro. The nematicidal volatile organic compounds (VOCs) from the fermentation broth of B. aryabhattai MCCC 1K02966 were investigated further using solid-phase microextraction gas chromatography-mass spectrometry. Four VOCs, namely, pentane, 1-butanol, methyl thioacetate, and dimethyl disulfide, were identified in the fermentation broth. Among these VOCs, methyl thioacetate exhibited multiple nematicidal activities, including contact nematicidal, fumigant, and repellent activities against M. incognita. Methyl thioacetate showed a significant contact nematicidal activity with 87.90% mortality at 0.01 mg/mL by 72 h, fumigant activity in mortality 91.10% at 1 mg/mL by 48 h, and repellent activity at 0.01–10 mg/mL. In addition, methyl thioacetate exhibited 80–100% egg-hatching inhibition on the 7th day over the range of 0.5 mg/mL to 5 mg/mL. These results showed that methyl thioacetate from MCCC 1K02966 control M. incognita with multiple nematicidal modes and can be used as a potential biological control agent.     

Two nematicidal furocoumarins from Ficus carica L. leaves and their physiological effects on pine wood nematode (Bursaphelenchus xylophilus)

The ethanol extract of the Ficus carica L. leaves was tested to show strong nematicidal activity against pine wood nematode (PWN), Bursaphelenchus xylophilus, causing 90.93% corrected mortality within 72 h at 1.0 mg/mL. From the ethyl acetate soluble fraction of the F. carica L. leaves extract, the main nematicidal constituents were obtained by bioassay-guided isolation and identified as linear furocoumarins bergapten (1) and psoralen (2) by mass and NMR spectral data analysis. Bergapten and psoralen had significant nematicidal activity against PWN with the LC₅₀ values of 97.08 aKSnd 115.03 μg/mL within 72 h, respectively. The two furocoumarins could inhibit the activities of amylase, cellulase and acetylcholinesterase (AchE) from PWN. The morphologies of PWNs changed much after they were treated by bergapten and psoralen. The physiological effects of bergapten and psoralen on PWN might provide helpful clues to elucidate their nematicidal mechanisms.     

Antiproliferative activity of Luehea candicans Mart. et Zucc. (Tiliaceae)

Luehea candicans Mart. et Zucc. (Tiliaceae) is known as 'a?oita-cavalo' and is one of the most important medicinal plants found in the Brazilian cerrado. The crude methanolic extracts of the branches and leaves and their fractions were evaluated using the following cancer cell lines: MCF-7 (breast), NCI-ADR (breast expressing the multidrug resistance phenotype), NCI-460 (lung), UACC-62 (melanoma), 786-0 (kidney), OVCAR (ovarian), PCO-3 (prostate), HT-29 (colon) and K-562 (leukaemia). The crude methanolic extracts from the branches (B) and leaves (L) were able to inhibit the growth of the K-562 and 786-0 cell lines in a dose-dependent manner, with GI(50) values of 8.1 and 5.4 μg mL(-1), respectively. The hexane (L1), chloroform (L2) and methanol (L4) fractions derived from extract L showed a high selectivity and pronounced cytostatic activity against 786-0 (GI(50) ~ 40 μg mL(-1)). A significant amount of lupeol was isolated from fraction L2. The chloroform (B2) and methanol (B3) fractions derived from extract (B) exhibited less selectivity, showing the highest cytostatic activity against K-562, NCI-ADR, OVCAR, MCF-7 and NCI-460 cells, with GI(50) values between 27 and 40 μg mL(-1). Lupeol, betulin, a mixture of steroids, (-)-epicatechin, vitexin and liriodendrin were isolated from these active fractions.     

A new eudesmane sesquiterpene glucoside from Liriope muscari fibrous roots

The screening of several Chinese medicinal herbs for nematocidal properties showed that the ethanol extract of Liriope muscari fibrous roots possessed significant nematocidal activity against the pine wood nematode (Bursaphelenchus xylophilus). From the ethanol extract, a new constituent (1,4-epoxy-cis-eudesm-6-O-β-D-glucopyranoside) and three known glycosides [1β,6α-dihydroxy-cis-eudesm-3-ene-6-O-β-D-glucopyranoside (liriopeoside A), 1β,6β-dihydroxy-cis-eudesm-3-ene-6-O-β-D-glucopyranoside, and 1α,6β-dihydroxy-5,10-bis-epi-eudesm-4(15)-ene-6-O-β D-glucopyranoside] were isolated by bioassay-guided fractionation. The structures were elucidated by 1D and 2D NMR and MS techniques. 1,4-Epoxy-cis-eudesm-6-O-β-D-glucopyranoside possessed moderate nemato-cidal activity against B. xylophilus with a LC(50 )value of 339.76 μg/mL, while liriopeoside A (LC(50) = 82.84 μg/mL) and 1β,6β-dihydroxy-cis-eudesm-3-ene-6-O-β-D-glucopyranoside (LC(50) = 153.39 μg/mL) also exhibited nematocidal activity against B. xylophilus. The crude extract of L. muscari fibrous roots exhibited nematocidal activity against the pine wood nematode with a LC(50) value of 182.56 μg/mL.     

Synthesis and nematicidal evaluation of 1,2,3-benzotriazin-4-one derivatives containing piperazine as linker against Meloidogyne incognita

To explore new skeleton with nematicidal activity, a series of novel 1,2,3-benzotriazin-4-one derivatives containing piperazine as linker were synthesized and varied fragments were also introduced to increase structure diversity of thenew skeleton.     

1-芳基-3-(3-(4-氧香豆素基)苯基)硫脲衍生物的合成及抑菌活性

为了筛选出具有较高抑菌活性的含香豆素的硫脲类衍生物,本文以4-羟基香豆素为原料,经氯化、醚化、异硫氰酸化和加成反应合成了一系列1-芳基-3-(3-(4-氧香豆素基)苯基)硫脲衍生物,其结构经红外光谱(IR)、核磁共振谱(NMR)和质谱(MS)等技术手段进行了表征。结果表明,目标化合物对水稻白叶枯菌和柑橘溃疡菌均具有较好的抑制活性。其中化合物4k、4l、4m和4n抑制水稻白叶枯菌活性EC_(50)值分别为137.42、131.05、129.23和117.43 mg/L,优于对照药剂噻菌铜的活性(195.24 mg/L);化合物4k、4l、4m和4n抑制柑橘溃疡菌活性EC_(50)值分别为97.02、94.31、102.28和90.52 mg/L,优于噻菌铜的活性(120.25 mg/L)。     

Nematocidal flavone-C-glycosides against the root-knot nematode (Meloidogyne incognita) from Arisaema erubescens tubers

A screening of several Chinese medicinal herbs for nematicidal properties showed that Arisaema erubescens (Wall.) Schott tubers possessed significant nematicidal activity against the root-knot nematode (Meloidogyne incognita). From the ethanol extract, two nematicidal flavone-C-glycosides were isolated by bioassay-guided fractionation. The compounds were identified as schaftoside and isoschaftoside on the basis of their phytochemical and spectral data. Schaftoside and isoschaftoside possessed strong nematicidal activity against M. incognita (LC(50) = 114.66 μg/mL and 323.09 μg/mL, respectively) while the crude extract of A. erubescens exhibited nematicidal activity against the root-knot nematode with a LC(50) value of 258.11 μg/mL.     

Phenylethyl cinnamides as potential alpha-glucosidase inhibitors from the roots of Solanum melongena

Bioassay-guided fractionation against alpha-glucosidase resulted in isolation and identification of six phenolic compounds (1-6) from the 70% EtOH extract of the roots of Solanum melongena L. (Solanaceae). Of these, three phenylethyl cinnamides, N-trans-feruloyl tyramine (1), N-trans-p-coumaroyl tyramine (2) and N-cis-p-coumaroyl tyramine (3) possessed inhibitory activity against alpha-glucosidase with IC50 values of 500.6, 5.3 and 46.3 microM, respectively. Mechanism analysis revealed these phenylethyl cinnamides were non-competitive inhibitors. This is the first study of the alpha-glucosidase inhibitory activities of the roots of S. melongena, and this preliminary observation suggested potential medicinal use of this herb.     

Chemical Characterization of Plant Extracts and Evaluation of their Nematicidal and Phytotoxic Potential

Nacobbus aberrans ranks among the “top ten” plant-parasitic nematodes of phytosanitary importance. It causes significant losses in commercial interest crops in America and is a potential risk in the European Union. The nematicidal and phytotoxic activities of seven plant extracts against N. aberrans and Solanum lycopersicum were evaluated in vitro, respectively. The chemical nature of three nematicidal extracts (EC_50,48h ≤ 113 µg mL⁻¹) was studied through NMR analysis. Plant extracts showed nematicidal activity on second-stage juveniles (J2): (≥87%) at 1000 µg mL⁻¹ after 72 h, and their EC₅₀ values were 71.4–468.1 and 31.5–299.8 µg mL⁻¹ after 24 and 48 h, respectively. Extracts with the best nematicidal potential (EC_50,48h < 113 µg mL⁻¹) were those from Adenophyllum aurantium, Alloispermum integrifolium, and Tournefortia densiflora, which inhibited L. esculentum seed growth by 100% at 20 µg mL⁻¹. Stigmasterol (1), β-sitosterol (2), and α-terthienyl (3) were identified from A. aurantium, while 1, 2, lutein (4), centaurin (5), patuletin-7-β-O-glucoside (6), pendulin (7), and penduletin (8) were identified from A. integrifolium. From T. densiflora extract, allantoin (9), 9-O-angeloyl-retronecine (10), and its N-oxide (11) were identified. The present research is the first to report the effect of T. densiflora, A. integrifolium, and A. aurantium against N. aberrans and chemically characterized nematicidal extracts that may provide alternative sources of botanical nematicides.     

The nematocidal activity and the structure-activity relationships of stilbenes

The pinewood nematode, Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle, is the causative agent of the pine wilt disease which has been devastating forests of Pinus densiflora Sieb.et Zucc. and P. thunbergii Parl. in Japan. To prevent the pine wilt disease, the development of nematocidal compound is required. Twenty-one synthesized stilbenes (1)-(20), (23), salicylic acid (21), and phenylsalicilate (22) were examined for their nematocidal activity against an isolate of B. xylophilus (T-4). Among the tested compounds, two fluorinated stilbenes (15) and (13), were found to be most potent compounds against T-4, demonstrating 99% and 98% lethality at 10 ppm concentration. The LD50 values of compounds 15 and 13 were 3 ppm, respectively.     

α-蒎烯含氮衍生物的合成及其杀松材线虫活性的研究

<以α-蒎烯为原料, 经硼氢化-氧化、胺化及选择性还原等步骤合成了系列3-蒎酮亚胺和3-蒎胺类化合物, 探索了3-蒎酮亚胺和3-蒎胺的不同结构与杀松材线虫活性的关系. 采用FT-IR, 1H NMR, 13C NMR, GC-MS等分析手段对蒎酮亚胺和蒎胺类化合物的结构进行了表征. 结果表明: N-苯基-3-蒎酮亚胺具有很强的杀松材线虫活性, 在1×10－3 µL/mL (约1×10－3 mg/mL) 浓度下, 在24, 48和72 h内杀线虫效率分别达到89.28%, 89.58%和95.75%, 该化合物极具开发潜力.     

Antibacterial phenolic compounds from the spines of Gleditsia sinensis Lam

This study was to isolate antibacterial compounds from Gleditsia sinensis Lam. spines through bioassay-guided fractionation (against a Gram-positive bacterium Xanthomonas vesicatoria and a Gram-negative bacterium Bacillus subtilis). The crude ethanol extract of G. sinensis spines was partitioned sequentially with solvents of increasing polarity. The ethyl acetate fraction, which exhibited the most significant antibacterial activities among all the solvent fractions, was further separated by column chromatograph, yielding seven phenolic compounds including ethyl gallate (1) and caffeic acid (7), and five flavonoids, dihydrokaempferol (2), eriodictyol (3), quercetin (4), 3,3',5',5,7-pentahydroflavanone (5) and (-)-epicatechin (6). Compounds 4, 5 and 7 showed moderate inhibitory activities against both bacterial species, with compound 7 having the lowest minimal inhibitory concentration (MIC) of 0.125 mg mL(-1), while compounds 1 and 2 showed a weak inhibitory activity only against B. subtilis (MIC 1.00 mg mL(-1)), and compounds 3 and 6 showed insignificant activity against the two bacteria.     

Cytotoxic and insecticidal activities of derivatives of harmine, a natural insecticidal component isolated from Peganum harmala

In a continuing effort to develop novel β-carbolines endowed with better insecticidal activity, a simple high-yielding method for the synthesis of harmine compounds starting from L-tryptophan has been developed and a series of 1,3-substituted β-carboline derivatives have been synthesized and evaluated for their cytotoxicity against insect cultured Sf9 cell line in vitro and insecticidal activities against 4th instar larvae of mosquitos, Culex pipiens quinquefasciatus and mustard aphid, Lipaphis erysimi. The results demonstrated that 1-phenyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (compound 2) and methyl 1-phenyl-β-carboline-3-carboxylate (compound 13) represented the best potential compounds, with Sf9 cells inhibition rates of 71.55% and 60.21% after 24 h treatment at concentrations of 50-200 mg/L, respectively. Both compounds 2 and 13 also showed strong insecticidal activity towards 4th instar larvae of mosquitos with LC(50) values of 20.82 mg/L and 23.98 mg/L, and their LC(90) values were 88.29 mg/L and 295.13 mg/L, respectively. Furthermore, the LC(50) values of compounds 2 and 13 against mustard aphids were 53.16 mg/L and 68.05 mg/L, and their LC(90) values were 240.10 mg/L and 418.63 mg/L after 48 h treatment. The in vitro cytotoxicity of these compounds was consistent with the insecticidal activity in vivo. The results indicated that the 1- and 3-positions of the β-carboline ring deserve further investigation to develop biorational insecticides based on the natural compound harmine as a lead compound.     

Anti-plasmodial and cholinesterase inhibiting activities of some constituents of Psorospermum glaberrimum

Glaberianthrone (1), a new bianthrone was isolated from the hexane extract of the stem bark of Psorospermum glaberrimum together with thirteen known compounds: 3-geranyloxyemodin anthrone (2), friedelan-3-one (3), 3-prenyloxyemodin anthrone (4), 3-geranyloxyemodin (5), 3-prenyloxyemodin (6), friedelan-3-ol (7), acetylvismione D (8), betulinic acid (9), 2-geranylemodin (10), bianthrone A2b (11), bianthrone 1a (12), emodin (13) and 2-prenylemodin (14). The structures of the isolated compounds were established by means of spectroscopic methods. The extracts and the isolated compounds were tested in vitro for their anti-plasmodial activity against Plasmodium falciparum (chloroquine resistant strain W2) and for their acetyl- and butyrylcholinesterase inhibitory properties. The n-hexane extract showed good anti-plasmodial activity against P. falciparum W2 strain, with IC(50) of 0.87 microg/ml. It also exhibited 65.5% and 98.2% of acetyl- and butyrylcholinesterase inhibition at 0.2 mg/ml, respectively. Compounds 2 and 8 showed the best potencies against P. falciparum W2 strain with IC(50) of 1.68 microM and 0.12 microM, (0.66 microg/ml and 0.054 microg/ml) respectively. All tested compounds showed good butyrylcholinesterase inhibition activities with compound 12 displaying the best potency (IC(50) 9.25+/-0.25 microM). All the tested compounds showed weak inhibitory activity against acetylcholinesterase.     

In-vitro antagonistic characteristics of crude aqueous and methanolic extracts of Garcinia kola (Heckel) seeds against some Vibrio bacteria

The methanolic and aqueous extracts of Garcinia kola seeds were screened for their anti-Vibrio activities against 50 Vibrio isolates obtained from wastewater final effluents in the Eastern Cape Province, South Africa. The crude extracts at 10 mg/mL exhibited appreciable inhibitory activities against most of the test Vibrio isolates, with zones of inhibition ranging from 10-19 mm for methanol extract and 8-15 mm for the aqueous extracts. The minimum inhibitory concentrations (MIC) of the methanol extract varied from 0.313 to 2.5 mg/mL while that for the aqueous extract was 10 mg/mL for all the susceptible Vibrio isolates. Rate of kill assay of the methanolic extracts against three selected Vibrio species showed bacteriostatic activities against all of them achieving 58% and 60% (Vibrio vulnificus AL042); 68% and 69% (Vibrio parahaemolyticus AL049); and 70% and 78% (Vibrio fluvialis AL040) killing of the test bacteria at 3× and 4 ×MIC values, respectively, after 2 h exposure time. We conclude that Garcinia kola seeds hold promise as a potential source of therapeutic compounds of relevance in Vibrio infections management.     

Synthesis and bioactivity of novel 3-(1-hydroxyethylidene)-5-substituted-pyrrolidine-2,4-dione derivatives

Ten novel 5-substituted derivatives of 3-(l-hydroxyethylidene)pyrrolidine-2,4-dione were synthesized.The compounds were confirmed by IR,:H NMR,MS and elemental analysis.The bioassay indicated that these compounds showed noticeable herbicidal activities,and compounds 6f and 6j exhibited excellent inhibitory activities against the stalk of Echinochloa crusgalli,with EC50 values of 94.4 and 72.7 mg/L,respectively.     

2-[4-(2,6-二氟苯基)噻唑-2-基]-3-羟基丙烯腈衍生物的合成及生物活性

为了寻找生物活性良好的噻唑基丙烯腈类化合物, 利用2-[4-(2,6-二氟苯基)噻唑-2-基]乙腈(3)分别与取代氯甲酸酯4和取代苯基异氰酸酯6在碱存在下反应, 合成了8个2-[4-(2,6-二氟苯基)噻唑-2-基]-3-羟基-3-烃氧基丙烯腈化合物5和7个2-[4-(2,6-二氟苯基)噻唑-2-基]-3-羟基-3-取代苯胺基丙烯腈化合物7, 均为首次报道的丙烯腈类化合物. 化合物结构经1H NMR, IR, MS和元素分析表征. 初步生物活性测定结果表明, 在试验浓度下, 目标化合物均具有一定的杀虫和抑菌活性, 其中化合物5f和5h在100 mg/L浓度下对炭疽病菌的抑制率达95%; 化合物5g和7d在250 mg/L浓度下对棉红蜘蛛的致死率达85%.     

N-(2-(腈基(4,6-二甲氧基嘧啶-2-基)甲基)苯基)酰胺类衍生物的合成及生物活性

以2-(2-硝基苯基)乙腈及4,6-二甲氧基-2-甲磺酰基嘧啶为起始原料,分别经缩合、还原及酰胺化反应合成了6个未见文献报道的N-(2-(腈基(4,6-二甲氧基嘧啶-2-基)甲基)苯基)酰胺类衍生物,其结构经1H NMR、MS和元素分析进行了确证。 在150 g/hm2的用量条件下,合成化合物未显示出除草活性。 在200 mg/L浓度下,部分化合物对黄瓜灰霉病及水稻纹枯病表现出一定的抑菌作用,其中化合物4d对水稻纹枯病的抑制率为72.33%。     

Synthesis and pesticidal activities of novel anthranilic diamides containing pyridylpyrazole and iminodithiocarbamate or thiosemicarbazone motifs

Abstract

A series of novel anthranilic diamide derivatives containing pyridylpyrazole and iminodithiocarbamate or thiosemicarbazone motifs were synthesized via multi-step reactions. The structures of seven title compounds (methyl 2-(2-(3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxamido)-5-chloro-3- methylbenzylidene)hydrazinecarbodithioate 7 and 3-bromo-N-(2-((2-substitutedcarbamothioylhydrazono)methyl)-4-chloro-6-methylphenyl)-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxamide 8a-8f) were confirmed by melting points, IR, ¹H NMR, ¹³C NMR, and HRMS. The bioassays showed that some of the compounds exhibited modest insecticidal activities against oriental armyworm (Mythimna separata Walker), particularly, compound 8b (3-bromo-N-(4-chloro-2-methyl-6-((2-(methylcarbamothioyl)hydrazono)methyl)phenyl)-1-(3-chloropyridin-2-yl)-1H-pyrazole-5-carboxamide) held 100% and 30% larvicidal activity at the concentration of 25?mg/L and 10?mg/L, respectively. In addition, several compounds displayed favorable fungicidal activities against Alternaria solani Sorauer and Physalospora piricola at 50?μg/mL, and were comparable with the controls Chlorothalonil and Triadimefon. The results in this paper will provide important information for further research and development of sulfur-containing heterocyclic agrochemicals.