Total synthesis and herbicidal activity of natural rubrolides C, E and F.

Rubrolides are natural butyrolactones isolated from the tunicate , 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%.

Glycosides from the leaves of Fraxinus Hubeiensis.

Fraxinus hubeiensis is a plant endemic to China and widely used as folk medicine to treat various diseases. However, its chemical constituents have never been reported sufficiently. Thus, the primary objective of this study was to investigate the phytochemical constituents and biological activities of F.

An Exploration of the Effect of the Kleier Model and Carrier-Mediated Theory to Design Phloem-Mobile Pesticides Based on Researching the N-Alkylated Derivatives of Phenazine-1-Carboxylic Acid-Glycine.

The Kleier model and Carrier-mediated theory are effective for molecularly designing pesticides with phloem mobility. However, the single Kleier model or Carrier-mediated theory cannot achieve a reliable explanation of the phloem mobility of all exogenous substances. A detailed investigation of the two models and the scope of their applications can provide a more accurate and highly efficient basis for the guidance of the design and development of phloem-mobile pesticides.

Study on the selectivity and phloem mobility of Fenoxaprop-P amino acid ester conjugates on rice and barnyard grass.

To improve the selectivity of the fenoxaprop herbicide to rice and barnyard grass, a series of fenoxaprop-P-ethyl-amino acid ester conjugates were designed and synthesized, and tested for biological activity as well as their phloem mobility. The bioassay results indicated that the target compounds possessed better activity against barnyard grass (Echinochloa crusgalli) than rape (Brassica campestris L.) at the concentration of 0.

Fungicidal Action of the Triphenylphosphonium-Driven Succinate Dehydrogenase Inhibitors Is Mediated by Reactive Oxygen Species and Suggests an Effective Resistance Management Strategy.

Succinate dehydrogenase (SDH) is an effective target of SDH inhibitor (SDHI) fungicides which received more and more attention in recent years. However, there is no good solution to their rapidly growing drug resistance caused by frequent use. In this study, three triphenylphosphonium (TPP)-conjugated boscalid analogues were synthesized and tested for antifungal activities.

Synthesis and insecticidal activity of the fluorinated galegine analogues.

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 Geoffroy and Glover, in particular, compounds IIa-05, IId-02 and IIe-03 show the best insecticidal activities against with the mortality of 100%, 100% and 96.

Chemical Composition and Attractant Activity of Volatiles from to The Spring Aphid .

Maxim, a type of sumac, is an economically important tree widely cultivated in mountainous areas of western and central China. A gall, called the bellied gallnut, induced by the aphid, Takagi, is important in the food, medical, and chemical industries in China. Volatiles from were found to attract , but little is known about them.

Synthesis and fungicidal activity of phenazine-1-carboxylic triazole derivatives.

A total of 15 novel-substituted 3-(benzylsulfanyl)-1H-1,2,4-triazol-5-ylamine and 10 novel-substituted 3-benzylmercapto-1,2,4-triazol derivatives were synthesized based on the natural product phenazine-1-carboxylic acid (PCA). Their structures were confirmed by H-NMR, C-NMR, HRMS, and X-ray. Most substituted 3-benzylmercapto-1,2,4-triazol derivatives displayed very strong fungicidal activity against one or multiple plant pathogens and .

Effect of introducing amino acids into phenazine-1-carboxylic acid on phloem mobility.

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 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.

Synthesis and herbicidal activity against barnyard grass of novel diarylmethanone O-(2,6-bis((4,6-dimethoxypyrimidin-2-yl)oxy)benzoyl)oximes.

Background: Pyribenzoxim is an excellent herbicide that can effectively control barnyard grass. However, there are few reports of its structural analogs and structure-activity relationship (SAR), which makes pyribenzoxim an isolated case. Here, a series of diarylmethanone oxime esters characterized by pyridine heterocycles were designed and synthesized for herbicidal screening and SAR investigation against barnyard grass.

Chemical Constituents from and Their Antifungal and Herbicidal Activities.

The phytochemical investigation of led to the isolation and characterization of ten compounds which were identified as fraxin (), fraxetin (), esculetin (), cichoriin (), euphorbetin (), kaempferol-3---rutinoside (), oleuropein (), linoleic acid (), methyl linoleate (), and -sitosterol (). Structures of the isolated constituents were characterized by H NMR, C NMR and HRMS. All the compounds, except compounds and were isolated for the first time from this plant.

Screening Effective Antifungal Substances from the Bark and Leaves of by the Bioactivity-Guided Isolation Method.

To find good antifungal substances by the bioactivity-guided isolation method, we tracked down the effective antifungal substances in the bark and leaves of , and isolated three antifungal compounds , , and The structures were identified as xanthyletin, luvangetin, and avicennin by H-NMR, C-NMR, and HRMS spectra. Particularly, compound had several isomers, and the H-NMR spectra of 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.

Design and synthesis of novel hydrocarbylidene nitrohydrazinecarboximidamides against aphids based on natural product galegine.

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 at a concentration of 200 mg/L, and most compounds show excellet insecticidal activities against . In particular, compounds , , and show the equal activities to a commercial pesticide Imidacloprid with their LC values are 0.

The influence of steric configuration of phenazine-1-carboxylic acid-amino acid conjugates on fungicidal activity and systemicity.

Background: Conjugating an amino acid onto existing fungicidal parent structures has been demonstrated to be an effective way to endow non-phloem mobile fungicides with phloem mobility. To alter the systemicity of the fungicide PCA (phenazine-1-carboxylic acid), 10 amino acids derivatives of this fungicide were designed and synthesized, and their synthesis, characterization, phloem and xylem mobility in Ricinus communis L, and their fungicidal activity in vitro are described.

Results: The systemicity experiments in Ricinus communis system demonstrated that all conjugates exhibited obvious phloem mobility compared with non-phloem-mobile PCA, and the introduction of an L-amino acid to PCA more greatly enhanced the phloem mobility.

Synthesis and bioactivities of phenazine-1-carboxylic piperazine derivatives.

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 H NMR and HRMS. Most compounds exhibited certain fungicidal activities.

Design, synthesis and biological activity of hydroxybenzoic acid ester conjugates of phenazine-1-carboxylic acid.

We prepared 16 novel hydroxybenzoic acid ester conjugates of phenazine-1-carboxylic acid (PCA) and investigated their biological activity. Most of the synthesized conjugates displayed some level of fungicidal activities in vitro against five phytopathogenic fungi. Nine conjugates 5b, 5c, 5d, 5e, 5h, 5i, 5m, 5n and 5o (EC between 3.

Synthesis and fungicidal activity of 1,3,4-oxadiazol-2-yl thioether derivatives containing a phenazine-1-carboxylic acid scaffold.

To find new higher fungicidal activities lead compounds and develop new eco-friendly agrochemicals, natural product phenazine-1-carboxylic acid (PCA) as scaffold, a series of 1,3,4-oxadiazol-2-yl thioether derivatives was synthesized and bio-assayed. The results reveal that most target compounds possessed moderate to good fungicidal activities against , and Compounds and exhibit more than 90% bioactivity against . The EC value of compounds and are 11.

Design, Synthesis, Phloem Mobility, and Bioactivities of a Series of Phenazine-1-Carboxylic Acid-Amino Acid Conjugates.

Developing fungicides with phloem mobility that can be applied to leaves to control root or vascular pathogens has long been desirable. To achieve this goal, an efficient and economical strategy involves introducing an amino acid into the existing highly active parent pesticide molecule. Hence, 12 L-phenazine-1-carboxylic acid (PCA)-amino acid conjugates ⁻ were designed and synthesized via a simple synthetic route.

Synthesis and antifungal evaluation of PCA amide analogues.

To improve the physical and chemical properties of phenazine-1-carboxylic acid (PCA) and find higher antifungal compounds, a series of PCA amide analogues were designed and synthesized and their structures were confirmed by H NMR, HRMS, and X-ray. Most compounds showed some antifungal activities in vitro. Particularly, compound 3d exhibited inhibition effect against Pyriculariaoryzac Cavgra with EC value of 28.

Synthesis and bioactivities of diamide derivatives containing a phenazine-1-carboxamide scaffold.

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 H-NMR and HRMS. The bioassays showed that some of the target compounds exhibited promising fungicidal activities, and exhibited excellent and selective herbicidal activities.

Synthesis, fungicidal activity and phloem mobility of phenazine-1-carboxylic acid-alanine conjugates.

Phenazine-1-carboxylic acid (PCA) is a natural product that has been proven effective against a number of soil-borne fungal phytopathogens and registered for biofungicide against rice sheath blight in China. In order to improve the phloem mobility of phenazine-1-carboxylic acid (PCA), four PCA derivatives were designed and synthesized by conjugating PCA with l-alanine methyl ester, d-alanine methyl ester, l-alanine and d-alanine respectively. In vitro and planta bioassays results showed that conjugates L-PAM and D-PAM exhibited higher fungicidal activities against Rhizoctonia solani Kuhn than PCA while L-PA and D-PA were less active than PCA.

Synthesis and bioactivities of Phenazine-1-carboxylic acid derivatives based on the modification of PCA carboxyl group.

Phenazine-1-carboxylic acid (PCA) as a natural product widely exists in microbial metabolites of Pseudomonads and Streptomycetes and has been registered for the fungicide against rice sheath blight in China. To find higher fungicidal activities compounds and study the effects on fungicidal activities after changing the carboxyl group of PCA, we synthesized a series of PCA derivatives by modifying the carboxyl group of PCA and their structures were confirmed by H NMR and HRMS. Most compounds exhibited significant fungicidal activities in vitro.

Synthesis and bioactivities of amino acid ester conjugates of phenazine-1-carboxylic acid.

Phenazine-1-carboxylic acid (PCA) is a natural product that has been characterized by special chemical structures, interesting bioactivities and has been registered for fungicide against rice sheath blight in China. Phloem mobility is of great significance to long-distance transport of systemic pesticides in plants. In order to improve the phloem mobility and bioactivities of PCA, seventeen PCA-amino acid ester conjugates were designed and synthesized by conjugating PCA with different amino-acid esters.

A dehydrogenative cross-coupling reaction between aromatic aldehydes or ketones and dialkyl H-phosphonates for formyl or acylphenylphosphonates.

A novel DCC reaction between aromatic aldehydes or ketones and H-phosphonates has been developed for the synthesis of p-formyl or p-acylphenylphosphonates. The synthetic method has excellent para regioselectivities, good yields, and broad substrate scopes and is more benign to the environment. The DCC reaction also tolerates many functional groups, and results in a series of new p-formyl and p-acylphenylphosphonates, which should be important building blocks for the synthesis of versatile arylphosphonate derivatives.