Design, synthesis and insecticidal activity of novel hydrocarbylidene nitrohydrazinecarboximidamides.

BACKGROUND: Neonicotinoids, among the most important pesticides in recent decades, have played pivotal roles in controlling agricultural pests. However, the toxicity to some environmentally beneficial insects is a cause of concern. The development of novel insecticides safer to these insects is increasingly urgent. RESULTS: A novel series of hydrocarbylidene nitrohydrazinecarboximidamides were designed and synthesised, starting from S-methylisothiourea sulphate. Preliminary bioassays showed that the target molecules exhibited good activities against Lipaphis erysimi (turnip aphid) and Myzus persicae. As shown by initial insecticidal activity data, most of the target compounds had moderate to excellent activities at a concentration of 600 mg L-1 against L. erysimi, and the lethal rate of most compounds exceeded 90%. They were also highly effective against M. persicae. Some of them have shown excellent insecticidal activities, for example, the LC50 values of compounds Ie-02 to Ie-07 were found to be 3.8, 3.0, 2.5, 3.1, 4.1 and 4.0 mg L-1 respectively. CONCLUSION: Structure-activity relationship analysis indicated that a suitable flexible alkyl chain at the imine point and a Cl-substituted pyridine ring are the most crucial factors affecting the activity. © 2017 Society of Chemical Industry.

Studies on inhibition of respiratory cytochrome bc1 complex by the fungicide pyrimorph suggest a novel inhibitory mechanism.

The respiratory chain cytochrome bc1 complex (cyt bc1) is a major target of numerous antibiotics and fungicides. All cyt bc1 inhibitors act on either the ubiquinol oxidation (QP) or ubiquinone reduction (QN) site. The primary cause of resistance to bc1 inhibitors is target site mutations, creating a need for novel agents that act on alternative sites within the cyt bc1 to overcome resistance. Pyrimorph, a synthetic fungicide, inhibits the growth of a broad range of plant pathogenic fungi, though little is known concerning its mechanism of action. In this study, using isolated mitochondria from pathogenic fungus Phytophthora capsici, we show that pyrimorph blocks mitochondrial electron transport by affecting the function of cyt bc1. Indeed, pyrimorph inhibits the activities of both purified 11-subunit mitochondrial and 4-subunit bacterial bc1 with IC50 values of 85.0 µM and 69.2 µM, respectively, indicating that it targets the essential subunits of cyt bc1 complexes. Using an array of biochemical and spectral methods, we show that pyrimorph acts on an area near the QP site and falls into the category of a mixed-type, noncompetitive inhibitor with respect to the substrate ubiquinol. In silico molecular docking of pyrimorph to cyt b from mammalian and bacterial sources also suggests that pyrimorph binds in the vicinity of the quinol oxidation site.

(3R*)-Methyl 3-[(2S*)-4,6-dimethoxy-2-(4-methoxyphenyl)-3-oxo-2,3-dihydro-1-benzofuran-2-yl]-2-methoxycarbonyl-3-phenylpropionate.

The title compound, C(29)H(28)O(9), was isolated from the reaction of 4,6-dimeth-oxy-2-(4-methoxy-phen-yl)-3-benzofuran and α-methoxy-carbonyl-cinnaminate. The two aromatic rings form a dihedral angle of 22.7 (1)°. One methoxy-carbonyl group is disordered between two orientations in a 0.612 (4):0.388 (4) ratio. The crystal structure exhibits no significantly short inter-molecular contacts.

[The functional mechanism between the pesticide Pyrimorph and humic acid].

In the present experiment, we mainly discussed the function mechanism between the humic acid and a new kind of fungicide Pyrimorph, aiming to play a positive role in the reduction of contamination caused by pesticides on environment. After the disposition step by step, the humic acid was separated into three parts. Then IR and fluorescence analytical methods were employed to explain the functional mechanism between the pesticide and each part of humic acid. As a result, there are extensive interactions between the three parts of the humic acid and the fungicide Pyrimorph. The interactions between fulvic acid and Pyrimorph are mainly the H-bond and the transfer of the electric charge caused by the C=O of the Pyrimorph and the -OH of the fulvic acid, and the interaction between matomeilon and Pyrimorph is mainly the transfer of the electric charge, and the interaction between humin and Pyrimorph is the weakest. It was showed that the fulvic acid is the most active part in the humic acid. That's to say the intensity of the interaction between the three parts of the humic acid and the fungicide Pyrimorph is smaller and smaller with the order of molecular weight from small to big, namely fulvic acid, matomeilon acid and humin.

[Study on the molecular recognization of fungicide of kresoxim-methyl with beta-cyclodextrin and its derivatives].

The molecular recognition of fungicide of kresoxim-methyl with beta-cyclodextrin (beta-CD), methyl-beta-cyclodextrin (RAMEB)and hydroxypropyl-beta-cyclodextrin (RAMEB) was investigated by using UV-Vis spectroscopy analysis. The effect of temperature and polarity of solvent on the recognition interaction was studied. The driving force and the possible structure of the inclusion complexes were also discussed. The results presented that they formed inclusion complexes with a stoichiometry of 1:1, and the formation constant of inclusion complexes was in the order of Ku(HP-beta-CD)>(beta-CD)Kp(RAMEB) at 298.15 K. Elevation of the temperature triggered a decrease in stability of the inclusion complexes and the value of K(beta-D) was the biggest at > or =303.15 K. The formation constant reduced sharply with the decreasing polarity of the solvent. The standard molar Gibbs energies, enthalpies and entropies were all negative. All the results indicated that the association of the guest molecule with beta-CD was favored by enthalpy changes, and hydrophobicity and hydrogen bond interaction were main driving forces for the inclusion reaction. Our findings provided an important proof for the use of inclusion complexes of kresoxim-methyl with CDs.