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The introduction of fluorine atom can increase the biological activities of the target compounds remarkably. To find more safe and efficient insecticides, natural product galegine as lead compound, a series of novel fluorinated galegine analogues were designed and synthesized. The bioassay results indicate that all the target compounds have moderate to high insecticidal activities against Hyalopterus pruni Geoffroy and Aphis gossypii Glover, in particular, compounds IIa-05, IId-02 and IIe-03 show the best insecticidal activities against Hyalopterus pruni with the mortality of 100%, 100% and 96.6%, respectively. And compounds IIa-02, IId-02, IId-04, IIc-01, IIc-02 and IId-01 show 0.6-7 times insecticidal activities against Aphis gossypii as Imidacloprid with their LC50 values are 0.28 mg/L, 0.38 mg/L, 0.33 mg/L, 0.09 mg/L, 0.03 mg/L and 0.12 mg/L, respectively The analysis of structure-activity relationship indicates that the compounds with difluoro-substituted benzene ring have more potent insecticidal activities than the single fluoro-substituted compounds. [ABSTRACT FROM AUTHOR]

To develop new phenazine carboxylic acid derivatives with better phloem mobility, five novel 7-amino acid substituted phenazine-1-carboxylic acids were synthesised by introducing amino acids into PCA at the 7-position. The phloem mobility experiments in Ricinus communis seedlings showed that retaining the carboxyl group of PCA and conjugating amino acids to its phenazine ring can also endow PCA with phloem mobility. Comparing our previous research, we found the amino acids substituted at 7-position on phenazine ring of PCA could clearly enhance the phloem mobility of PCA than that of amino acids conjugated with carboxyl group. Especially, the phloem transport concentration of the compound 7-L-isoleucine substituted PCA (7d) was 21 times higher than PCA-L-isoleucine conjugate (8d). These data suggest that the introduction of amino acids at different structural sites on the phenazine ring could effectively enhance the phloem mobility of PCA and it is worth a further study. [ABSTRACT FROM AUTHOR]

A series of novel hydrocarbylidene nitrohydrazinecarboximidamides were designed and synthesized using an insecticidal natural product Galegine as a lead compound. The bioassay results show that the target compounds exhibited moderate to good insecticidal activities against Hyalopterus pruni Geoffroy at a concentration of 200 mg/L, and most compounds show excellet insecticidal activities against Aphis gossypii Glover. In particular, compounds IIc-01, IIc-03, IIe-02 and IIf-01 show the equal activities to a commercial pesticide Imidacloprid with their LC50 values are 0.21 mg/L, 0.27 mg/L, 0.12 mg/L and 0.24 mg/L, respectively, and compounds IIc-02 and IIe-05 show 10 times insecticidal activities as much as Imidacloprid with their LC50 values both are 0.02 mg/L. Structure–activity relationship and 3D-QSAR analyses indicate that the introduction of fluorine atom is useful for increasing the insecticidal activity of target compounds. [ABSTRACT FROM AUTHOR]

Phenazine-1-carboxylic acid (PCA) as a natural product which has significant inhibition effects against many soil-borne fungal phytopathogens in agricultural application and has been registered in China as the fungicide against rice sheath blight. In order to find new higher fungicidal activities lead compounds and develop new eco-friendly agrochemicals, we introduced substructure piperazines which also have high biological activity into PCA, designed and synthesized a series of phenazine-1-carboxylic piperazine derivatives, and their structures were confirmed by 1H NMR and HRMS. Most compounds exhibited certain in vitro fungicidal activities. In particular, Compounds 5r exhibited the activity against all the tested pathogenic fungi, such as Rhizoctonia solani, Alternaria solani, Fusarium oxysporum, Fusarium graminearum, Pyricularia oryzac Cavgra, with the EC50 value of 24.6μM, 42.9μM, 73.7μM, 73.8μM, 34.2μM, respectively, more potent activities than PCA (33.2μM, 81.5μM, 186.5μM, 176.4μM, 37.3μM). This result provided a highly active lead compound for the further structure optimization design. [ABSTRACT FROM AUTHOR]

Taking natural product phenazine-1-carboxamide (PCN) as a lead compound, a series of novel phenazine-1-carboxylic acid diamide derivatives were designed and synthesised. Their structures were confirmed by 1H-NMR and HRMS. The bioassays showed that some of the target compounds exhibited promising in vitro fungicidal activities, and exhibited excellent and selective herbicidal activities. Particularly, compounds c, h, o and s displayed root length inhibition activities against barnyard grass with the rate of more than 80%. Compound c exhibited the best activity among all the target compounds against barnyard grass stalk length with the IC50 value of 0.158 mmol/L, and compound o exhibited the best and wide spectrum inhibition against barnyard grass root length and rape in both root length and stalk length herbicidal activities with its IC50 values of 0.067, 0.048 and 0.059 mmol/L respectively. The analysis of preliminary Structure-Activity Relationships provides the theoretical basis for further design of phenazine-1-carboxylic acid. [ABSTRACT FROM AUTHOR]

To find good antifungal substances by the bioactivity-guided isolation method, we tracked down the effective antifungal substances in the bark and leaves of Zanthoxylum avicennae, and isolated three antifungal compounds 1, 2, and 3. The structures were identified as xanthyletin, luvangetin, and avicennin by 1H-NMR, 13C-NMR, and HRMS spectra. Particularly, compound 2 had several isomers, and the 1H-NMR spectra of 2 in different solvents showed a significant difference. To determine the stereo structure of 2, a single crystal was prepared and identified by X-ray diffraction as Luvangetin. Moreover, the difference of 1H-NMR data of 2 between in solvent dimethyl sulfoxide-d6 (DMSO-d6) and deuterated chloroform (CDCl3), and other reported isomers were discussed for the first time. The bioassay results indicated that the three compounds 1, 2, and 3 displayed low to high antifungal activities against tested phytopathogenic fungi. In particular, all compounds 1, 2, and 3 showed excellent antifungal activities against Pyricularia oryzae and Z. avicennae, with the values of half maximal effective concentration (EC50) ranging from 31 to 61 mg/L, and compound 3 was also identified as a more potent inhibitor against Fusaium graminearum (EC50 = 43.26 ± 1.76 mg/L) compared with fungicide PCA (phenazine-1-carboxylic acid) (EC50 = 52.34 ± 1.53 mg/L). The results revealed that compounds 1, 2, and 3 were the main antifungal substances of Z. avicennae, and can be used as lead compounds of a fungicide, which has good development value and prospect. [ABSTRACT FROM AUTHOR]

Rubrolides are natural butyrolactones isolated from the tunicate Ritterella rubra , shows antibacterial, antiviral and plant photosynthesis inhibitory activities. In this study, a facile total synthetic method for preparing the rubrolides from benzaldehyde by a Darzens reaction, aldol reaction and vinylogous aldol condensation in five steps is presented. Three natural rubrolides (E, C and F) were synthesised in the total yields of 25-40%. The bioassay results indicate that rubrolides E, C and F exhibit some herbicidal inhibitory effect against rapeseed, in particular, rubrolide F shows the best herbicidal activities against rapeseed root with the growth inhibitory rate of 72.8%. At greenhouse treatment concentrations of 100 and 500 mg/L, rubrolide F show a positive dose-toxicity correlation towards abutilon plants. Collectively, facile total Synthesis strategy provided the base for further bioactivities study of rubrolides family. Rubrolide F may be act as inhibitor of photosynthesis, and this could be lead structure of new herbicide.