Nematicidal Activity of Ten Kinds of Plant Extract against Hirschmanniella spp.

[Objective] The nematicidal activity of plant extracts was investigated. We aimed to explore a kind of botanical pesticide to control Hirschmanniella spp. [Method] The Chuanxiong （root）, agrimony （whole plant）, cocklebur （grain）, basil （leaves）, ragweed （stems and leaves）, green onion （root）, garlic （tuber）, Yuzhu （leaves）, marshpeper smartweed （whole plant）, horseweed （aboveground stems and leaves） were dried, grinded and sieved. The powders were then extracted by ethanol at room temperature for 24 h. The extract solutions were filtered through fil- ter pater. The obtained plant extracts were then diluted to determine their nematici- dal activities. [Result] The Chuanxiong extract had the highest nematicidal activity, followed by cocklebur extract, agrimony extract, basil extract, garlic extract, ragweed extract. The horseweed extract had the lowest nematicidal activity. [Conclusion] The Chuanxiong and other plants were natural, and they had a good environmental compatibility. They could be developed as botanical pesticides against Hirschman- niella spp.

Preparation, Characterization and Nematicidal Activity of Lansiumamide B Nano-Capsules

In this study, nano-capsules of lansiumamide B （NCLB） was prepared by the microemulsion polymerization method to improve the nematicidal efficacy of lansiumamide B （LB）. An optimal formulation was gained by orthogonal experiment design based on the encapsulation efficiency （E, %） value. The optimized NCLB were spherical and uniform under transmission electron microscopy （TEM）. The mean particle size, zeta potential and E, were （38.50~0.64） nm, （-70.5~0.76） mV and （95.13± 1.16）%, respectively. The release profile indicated that the accumulated release of LB in NCLB reached up to 82% within 96 h. Effects of NCLB against Bursaphelenehus xylophilus and J2 ofMeloidogyne incognita were reported in this paper. The nematicidal activity of NCLB has been remarkably increased, with LCs0 values of 2.1407 mg L-1 and 19.3608 mg L-1, respectively, at 24 h after treatment. The disease progression and the average number of root knots of Ipomoea aquatica were 1.50 and 7.25, respectively, in the treatment of NCLB, at concentration of 200 mg L-1 significantly lower than the treatment of LB and ethoprophos. Compared to control, the treatments of NCLB, LB and ethoprophos leaded the disease progression to drop 68.42, 36.84 and 26.32%, respectively, and caused the average number of root knots to fall 83.94, 78.03 and 63.66%. These results suggested that NCLB, as a novel nematicides formulation, performed more efficient and longer effective maintenance against plant parasitic nematodes.

Synthesis, nematicidal activity and docking study of novel chromone derivatives containing substituted pyrazole

A series of chromone derivatives containing substituted pyrazole were designed and synthesized.Preliminary bioassays showed that most of the synthesized compounds exhibited good nematicidal activity in vivo against Meloidogyne incognita at 10 mg/L. Among the tested compounds, A10 and A11 exhibited 100% inhibition rates. In addition, the molecular docking results indicated that both compound A10 and A11 interacts with amino acid residue Tyr121, Trp279, Tyr70, Trp84 and Phe330 of ACh E via hydrogen bond and p–p stacking. This investigation suggested that the chromone containing substituted pyrazole scaffold could be further optimized to explore novel, high-bioactivity nematicidal leads.

Synthesis, Nematicidal Activity, and 3D-QSAR of Novel 1,3,4-Oxadiazole/ Thiadiazole Thioether Derivatives

Forty one novel 1,3,4-oxadiazole/thiadiazole thioether derivatives containing phenoxy moiety were designed and synthesized. Bioassay demonstrated that some of them showed remarkable activities against Tylenchufus semipenetruns in vitro and in vivo. Compounds 20, 21, 35 and 39 showed excellent lethal activities after treatment for 48 h in vitro, with LC50 values of 13.4±1.8, 11.7±2.5, 13.7±2.4 and 13.31.1 mg.L-1, respectively, which were obviously superior to fosthiazate （49.1±2.8 mg.L-1） and avermectin （26.6±2.3 mg.L-1）. Compound 23. can effectively control the citrus nema- tode disease caused by T. semipenetruns at 200 mg.L-1 in vivo with （68±3）% inhibitory effect, which was even better than that of avermectin （（63±2）%）. The CoMFA and CoMSIA models of three-dimensional quantitative structure-activity relationships （3D-QSARs） were established. The compound 33 was designed based on the 3D-QSAR models with more vigorous nematicidal activities in vitro （LC50：9.8±1.4 mg.L-1） and in vivo （（70±5）%）. These results demonstrated that compound 33 can be considered as a potential nematicide.

Synthesis and nematicidal activity of piperazinedione derivatives based on the natural product Barettin

Nematodes are serious constraints of crop production worldwide. However, the traditional nematicides suffer from the side-effects, including environmental and human toxicity. Herein, more than 70 novel piperazinedione derivatives based on the natural product Barettin were synthesized and evaluated against the root-knot nematode Meloidogyne incognita（M. incognita）. While most of synthesized compounds exhibited certain nematicidal activity at high concentration, the best one showed a nematicidal activity of 75% at 2.4 mmol/L.

Design and synthesis of novel coumarin analogs and their nematicidal activity against five phytonematodes

The presence of hydroxyl groups at the C4 and C7 positions in coumarin backbone has been proposed as a potential modification site for providing excellent bioactivity according to previous studies. A series of novel coumarin derivatives were rationally designed and synthesized by use of a complex catalytic system for a targeted modification at the above sites. These derivatives were assayed for nematicidal activity. As predicted, the derivatization enhanced the activity of the coumarins against five nematodes.Compounds 7b, 9a, 10 c and 11 c showed significant strong nematicidal broad spectrum activity against all tested nematodes. Compound 10 c was the most effective with the lowest LC50 values against Meloidogyne incognita（5.1 mmol/L）, Ditylenchus destructor（3.7 mmol/L）, Bursaphelenchus mucronatus（6.4 mmol/L）, Bursaphelenchus B. xylophilus（2.5 mmol/L） and Aphelenchoides besseyi（3.1 mmol/L）,respectively. A brief investigation on the structure–activity relationships（SAR） revealed that the targeted modification by a C7 hydroxyl was optimum compared with that of a C4 hydroxyl and that the coupling chain length was crucial for the nematicidal activity.

Design, Synthesis, and Biological Activity of Novel Aromatic Amide Derivatives Containing Sulfide and Sulfone Substructures

In recent years,the damage caused by soil nematodes has become increasingly serious;however,the varieties and structures of the nematicides available on the market are deficient.Fluopyram,a succinate dehydrogenase inhibitor(SDHI)fungicide developed by Bayer AG in Germany,has been widely used in the prevention and control of soil nematodes due to its high efficiency and novel mechanism of action.In this paper,two series of novel target compounds were designed and synthesized with nematicidal and fungicidal fluopyram as the molecular skeleton in order to introduce sulfide and sulfone substructures.The structures were identified and characterized by 1H nuclear magnetic resonance(NMR),13C NMR,and high-resolution mass spectrometer(HRMS).The bioassays revealed that most of the compounds showed excellent nematicidal activities at 200 lgmL-1 in comparison with fluopyram,while the nematode mortality rate dropped sharply at 100μg·mL-1,except for compounds I-11 and II-6.In terms of fungicidal activity,compound I-9 was discovered to have an excellent inhibitory rate,and a molecular docking simulation was performed that can provide important guidance for the design and exploration of efficient fungicidal lead compounds.

Chemical Composition of Different Extracts of Conyza bonariensis: Insecticidal and Nematicidal Activities

C. bonariensis (L.) Cronq. known as hairy fleabane was first described in Argentina but it is now widely spread through most warmer regions of Europe, Africa, Asia, the Caribbean and Central America. In this work, a chemical analysis by liquid and gas chromatography coupled with mass spectrometry of the whole plant, aerial part, flowers and roots extracts of C. bonariensis harvested in Togo (West Africa) was carried out. Two acetylenic compounds Lachnophyllum ester and limonene were identified as the main components of essential oils while Lachnophyllum and Matricaria lactones were dominant in chloroform extracts. Based on the plant chemical compositions, essential oils and chloroform extracts were tested on cowpea weevil Callosobruchus maculatus adults which are considered as one of the most cosmopolitan pests of stored beans, and on freshly hatched second-stage juveniles of root-knot nematode Meloidogyne incognita. Results showed that the whole plant essential oil demonstrated an LC50/24h value of 1.75 μL oil/L air on C. maculatus while at 3.91 μL oil/L air, it showed 100% mortality. Furthermore, the plant root chloroform extracts partitioned in diethyl ether-hexane mixture showed the strongest nematicidal activity with an LC50/72h value of 0.47 mg/mL. Our findings suggest that the widely diffused plant C. bonariensis and its acetylenic constituents could be considered as potent botanical insecticidal and nematicidal agents.

DFT Study of Dimerization Sites in Imidazo[1,2-a]pyridinyl-chalcone Series

Quantum chemistry methods were performed in order to characterize the chemical reactivity on series of imidazo[1,2-a]pyridinyl-chalcone (IPC). In particular, the B3LYP/6-311G(d) theory level has been used to determine parameters which characterize the global and local reactivity on five molecules of the series. These compounds differ from one to another with the aryl groups. There are: 1-(2-methylimidazo[1,2-a]pyridin-3-yl)-3-phenylprop-2-en-1-one, 3-(4-fluorophenyl)-1-(2-methylimidazo [1,2-a]pyridin-3-yl)prop-2-en-1-one, 3-[4-(dimethylamino)phenyl]-1-(2-methylimidazo [1,2-a]pyridin- 3-yl)prop-2-en-1-one, 3-(2,4-dichlorophenyl)-1-(2-methylimidazo [1,2-a]pyridin-3-yl)prop-2-en-1-one, 3-(2,4-dichlorophenyl)-1-(2-methylimidazo [1,2-a]pyridin-3-yl)prop-2-en-1-one. All results lead to finding out that local nucleophilicity and electrophilicity of compounds are not substituent-dependant contrarily to their global nucleophilicity which prove to be more sensitive to the electron-donating character of the substituents. 3-[4-(Dimethylamino) phenyl]-1-(2-methylimidazo[1,2-a]pyridin-3-yl)prop-2-en-1-one was identified as the unique nucleophile compound by global reactivity. Respectively, the carbon atoms C5 and C14 are the prediction sites of electrophilic and nucleophilic attacks in the molecular skeleton of both molecules. Identification of interactions centres on IPC series is of great importance for organic synthesis and medicinal chemistry where the molecular hybridization strategy is very often used to improve biological activities of interesting therapeutic systems.

Design, Synthesis and Biological Activity of N-Sulfonyl Aromatic Amide Derivatives

Fifteen novel N-sulfonyl aromatic amide derivatives were designed and synthesized, and the structures were characterized by 1H-and 13C-NMR, EA and HRMS. The crystal structures of compounds I-8 and I-9 were obtained from X-ray diffraction: I-8 is of triclinic system, Mr = 372.35, space group P2_(1/n) with a = 7.9151(10), b = 8.5637(11), c = 12.2022(15) A, β = 86.865(2)o, V = 807.09(18) A^(3), Z = 2, F(000) = 384, D_(c) = 1.532 g/cm^(3), the final R = 0.0408 and wR = 0.1068 for 2836 unique reflections with 2435 observed ones(I > 2σ(I)). I-9 belongs to triclinic system, M_r = 407.39, space group P2_1/n, with a = 8.4911(8), b = 8.6053(9), c = 14.5808(15) A, β = 77.1190(10)o, V = 995.44(17)A^(3), Z = 2, F(000) = 416, D_(c) = 1.359 g/cm^(3), the final R = 0.0567 and wR = 0.1779 for 3475 unique reflections with 2392 observed ones(I > 2σ(I)). The preliminary bioassay results indicated that the target compounds showed weak nematicidal activity, while compound I-5 displayed good fungicidal activity against Colletotrichum capsici with the inhibition rate of 61.7%.