Plant Fungicides Research Articles

Prenylated Flavonoids Isolated from the Root of Sophora flavescens as Potent Antifungal Agents against Botrytis cinerea.

Sophora flavescens, a traditional Chinese herb, produces a wide range of secondary metabolites with a broad spectrum of biological activities. In this study, we isolated six isopentenyl flavonoids (1-6) from the roots of S. flavescens and evaluated their activities against phytopathogenic fungi. In vitro activities showed that kurarinone and sophoraflavanone G displayed broad spectrum and superior activities, among which sophoraflavanone G displayed excellent activity against tested fungi, with EC50 values ranging from 4.76 to 13.94 μg/mL. Notably, kurarinone was easily purified and showed potential activity against Rhizoctonia solani, Botrytis cinerea, and Fusarium graminearum with EC50 values of 16.12, 16.55, and 16.99 μg/mL, respectively. Consequently, we initially investigated the mechanism of kurarinone against B. cinerea. It was found that kurarinone disrupted cell wall components, impaired cell membrane integrity, increased cell membrane permeability, and affected cellular energy metabolism, thereby exerting its effect against B. cinerea. Therefore, kurarinone is expected to be a potential candidate for the development of plant fungicides.

Antifungal Activity and Putative Mechanism of HWY-289, a Semisynthetic Protoberberine Derivative, against Botrytis cinerea.

The emergence of resistant pathogens has increased the demand for alternative fungicides. The use of natural products as chemical scaffolds is a potential method for developing fungicides. HWY-289, a semisynthetic protoberberine derivative, demonstrated broad-spectrum and potent activities against phytopathogenic fungi, particularly Botrytis cinerea (with EC50 values of 1.34 μg/mL). SEM and TEM imaging indicated that HWY-289 altered the morphology of the mycelium and the internal structure of cells. Transcriptomics revealed that it could break down cellular walls through amino acid sugar and nucleotide sugar metabolism. In addition, it substantially decreased chitinase activity and chitin synthase gene (BcCHSV) expression by 53.03 and 82.18% at 1.5 μg/mL, respectively. Moreover, this impacted the permeability and integrity of cell membranes. Finally, HWY-289 also hindered energy metabolism, resulting in a significant reduction of ATP content, ATPase activities, and key enzyme activities in the TCA cycle. Therefore, HWY-289 may be a potential candidate for the development of plant fungicides.

Engineered biodegradable nanopesticides for efficient leaf deposition and plant fungicides

AbstractPesticides are indispensable in agricultural development, but their effectiveness is often hindered by natural factors like rain‐off and degradation. Herein, tebuconazole nanopesticides (TEB NPs) with leaf‐adhesive, water‐stable, and small‐sized were successfully prepared by flash nanoprecipitation using the biodegradable polyethylene glycol‐b‐poly (lactic‐co‐glycolic acid) as a carrier. The nanopesticides could be efficiently deposited on plant leaves with uniform distribution and exhibited a 14° lower contact angle with foliage compared to commercial suspensions. The encapsulation of TEB within the polymer enhanced its resistance to photolysis, resulting in a 5‐h extension of its half‐life. TEB NPs were readily taken up by fungi and plants, thereby enhancing fungicidal efficacy. This nanopesticide could achieve the desired antifungal effect with reduced dosage and improved pesticide utilization. Therefore, the work is expected to provide a simple nanoplatform for improving pesticide utilization and promoting green agriculture.

MiR-181b-1-3p affects the proliferation and differentiation of chondrocytes in TD broilers through the WIF1/Wnt/β-catenin pathway

Thiram is a plant fungicide, its excessive use has exceeded the required environmental standards. It causes tibial dyschondroplasia (TD) in broilers which is a common metabolic disease that affects the growth plate of tibia bone. It has been studied that many microRNAs (miRNAs) are involved in the differentiation of chondrocytes however, their specific roles and mechanisms have not been fully investigated. The selected features of tibial chondrocytes of broilers were studied in this experiment which included the expression of miR-181b-1-3p and the genes related to WIF1/Wnt/β-catenin pathway in chondrocytes through qRT-PCR, western blot and immunofluorescence. The correlation between miR-181b-1-3p and WIF1 was determined by dual luciferase reporter gene assay whereas, the role of miR-181b-1-3p and WIF1/Wnt/β-catenin in chondrocyte differentiation was determined by mimics and inhibitor transfection experiments. Results revealed that thiram exposure resulted in decreased expression of miR-181b-1-3p and increased expression of WIF1 in chondrocytes. A negative correlation was also observed between miR-181b-1-3p and WIF1. After overexpression of miR-181b-1-3p, the expression of ACAN, β-catenin and Col2a1 increased but the expression of GSK-3β decreased. It was observed that inhibition of WIF1 increased the expression of ALP, β-catenin, Col2a1 and ACAN but decreased the expression of GSK-3β. It is concluded that miR-181b-1-3p can reverse the inhibitory effect of thiram on cartilage proliferation and differentiation by inhibiting WIF1 expression and activating Wnt/β-catenin signaling pathway. This study provides a new molecular target for the early diagnosis and possible treatment of TD in broilers.

Role of Flavonoids as Potential Plant Fungicides in Preventing Human Carcinogenesis: A Short Communication

In the context of the steadily increasing prevalence of malignant disorders all over the world, identification of any novel possibilities for suppressing carcinogenesis is crucial leading to saving human lives. One of the important sources of exposure to potential carcinogens is food products which can be contaminated with different types of mycotoxins. These structurally diverse chemicals are produced by certain fungi, whereas many of them may be associated with the development of malignant neoplasms in distinct organ systems. In this perspective article, the ability of specific plant secondary metabolites from the class of flavonoids to suppress the release of carcinogenic mycotoxins from certain fungi, mostly the members of Aspergillus and Penicillium genera, is highlighted. This finding might support the development of novel flavonoid-based plant fungicides in the future, to lower the contamination of food products with mycotoxins and thereby also reduce the cancer prevalence in humans. In addition, the application of flavonoids as natural products instead of synthetic chemicals in plant cultivation is probably also more acceptable for final consumers, representing an actual step toward a greener future.

Regioselective Claisen-Schmidt Adduct of 2-Undecanone from Houttuynia cordata Thunb as Insecticide/Repellent against Solenopsis invicta and Repositioning Plant Fungicides against Colletotrichum fragariae.

The U.S. Department of Agriculture (USDA) has established research programs to fight the phytopathogen Colletotrichum fragariae and the invasive red imported fire ant, Solenopsis invicta. C. fragariae is known to cause anthracnose disease in fruits and vegetables, while S. invicta is known for its aggressive behavior and painful stings and for being the cause of significant damage to crops, as well as harm to humans and animals. Many plants have been studied for potential activity against C. fragariae and S. invicta. Among the studied plants, Houttuynia cordata Thunb has been shown to contain 2-undecanone, which h is known for its antifungal activity against Colletotrichum gloesporioides. Based on the mean amount of sand removed, 2-undecanone showed significant repellency at 62.5 µg/g, similar to DEET (N,N-diethyl-meta-toluamide), against S. invicta. The 2-Undecanone with an LC50 of 44.59 µg/g showed toxicity against S. invicta workers. However, neither H. cordata extract nor 2-undecanone had shown activity against C. fragariae despite their known activity against C. gloesporioides, which in turn motivates us in repositioning 2-undecanone as a selected candidate for a Claisen-Schmidt condensation that enables access to several analogs (2a-f). Among the prepared analogs, (E)-1-(3-methylbenzo[b]thiophen-2-yl)dodec-1-en-3-one (2b) and (E)-1-(5-bromothiophen-2-yl)dodec-1-en-3-one (2f) showed promising activity against C. fragariae, revealing a distinctive structural activity relationship (SAR). The generated analogs revealed a clear regioselectivity pattern through forming the C=C alkene bond at position C-1. These data open the window for further lead optimization and product development in the context of managing C. fragariae and S. invicta.

Development of Simultaneous Determination Method of Pesticide High Toxic Metabolite 3,4-Dichloroaniline and 3,5 Dichloroaniline in Chives Using HPLC-MS/MS.

3,4-dichloroaniline (3,4-DCA) and 3,5-dichloroaniline (3,5-DCA) are, respectively, the primary metabolites deriving from the breakdown of phenylurea herbicides and dicarboximide fungicides in both soils and plants, whose residues in vegetable products have a heightened concern considering their higher health risks to humans and greater toxicity than the parent compounds in the environment. In this study, a sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the simultaneous determination of 3,4-DCA and 3,5-DCA residues in chive products based on the optimization of HPLC-MS/MS chromatographic and mass-spectrometric conditions using the standard substances and the modified QuEChERS preparation technique. The preparation efficiency of 3,4-DCA and 3,5-DCA from chive samples showed that acetonitrile was the best extractant. The combination of the purification agent graphite carbon black + primary secondary amine and the eluting agent acetonitrile + toluene (4:1, v/v) had a satisfactory purification effect. The linear correlation coefficients (R2) were more than 0.996 with the six concentration range of 0.001-1.000 mg/L for 3,4-DCA and 3,5-DCA. The limit of detection and limit of quantitation of this method was 0.6 and 2.0 µg/kg for 3,4-DCA, as well as 1.0 and 3.0 µg/kg for 3,5-DCA, respectively. The matrix effect range of 3,4-DCA and 3,5-DCA in chive tissues was from -9.0% to -2.6% and from -4.4% to 2.3%, respectively. The fortified recovery of 3,4-DCA and 3,5-DCA in chive samples at four spiked levels of 0.001-1.000 mg/kg was 75.3-86.0% and 78.2-98.1%, with the relative standard deviation of 2.1-8.5% and 1.4-11.9%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.6, 2.0, and 1.0, 3.03 for 4-DCA and 3,5-DCA, respectively. This study highlights that the analytical method established here can efficiently and sensitively detect residues of 3,4-DCA and 3,5-DCA residues for monitoring chive products. The method was successfully applied to 60 batches of actual vegetable samples from different regions.

The effect of fungicides on the physiological and biochemical state of lupine plants after seed treatment

Goal. To assess the effect of fungicides on the content of chlorophyll and the activity of antioxidant enzymes (peroxidase, catalase) in lupine plants after seed treatment.
 Methods. Laboratory and vegetation studies were carried out in the laboratory of analytical chemistry of pesticides of pesticides of the Institute of Plant Protection. The seeds of yellow lupine (Lupinus luteus L., variety Obriy) were treated with combined fungicides from different chemical classes: triazoles (cyproconazole, difenoconazole, tebuconazole, prothioconazole), phenylpyrroles (fludioxonil), carboxamides (carboxin), dithiocarbamates (thiram). Determination of the content of fungicides in plants was carried out using chromatographic methods of analysis. Chlorophyll content, peroxidase and catalase activity were determined by physicochemical methods according to generally accepted methods.
 Results. Fungicides activated the antioxidant systems of plants, depending on their physicochemical properties (in particular, the octanol-water partition coefficient Kow) and their content in plants (C, mg/kg). An increase in peroxidase activity (up to 89% compared to the control) was established within 30 days, which indicates the activation of antioxidant processes aimed at maintaining oxidative homeostasis in plants. The change in catalase activity under the influence of fungicides was inversely correlated with peroxidase activity, which is explained by the formation of adaptive mechanisms of ROS homeostasis. The high activity of peroxidase, compared to catalase, testifies to the important role of this enzyme in the redox reactions of plant resistance under the influence of fungicides. The total chlorophyll content under the action of fungicides, increased by 6—20%, compared to the control.
 Conclusions. Seed treatment with fungicides affects the course of redox reactions in plants, causing changes in the activity of key enzymes. The high activity of peroxidase against the background of fluctuations in catalase activity indicates the direct effect of fungicides on the state of antioxidant systems and the important role of peroxidase in maintaining ROS homeostasis. The stimulatory effect of fungicides on the accumulation of chlorophyll at the initial stages of growth of lupine plants was established, the content of which exceeded the control indicator by 6—20% by development phase. Changes in the activity of antioxidant enzymes (catalase and peroxidase) and the content of chlorophyll can serve as criteria for determining the levels of adaptation of lupine plants to the stress effect of fungicides.

In Vitro Anti-Bacterial and Anti-Fungal Activities of Extracts from Different Parts of 7 Zingiberaceae Plants

This study aimed to explore the anti-bacterial and anti-fungal activities of extracts from different parts of plants in the Zingiberaceae family. The inhibitory rate, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) of leaf and stem, and root and rhizome extracts from Alpinia katsumadai Hayata, Alpinia oxyphylla Miq × Alpinia henryi K. Schumann, Alpinia oblongifolia Hayata, Alpinia nigra (Gaertn.) Burtt, Amomum villosum Lour, Alpinia zerumbet (Pers.) Burtt. et Smith and Alpinia oxyphylla Miq were determined using the fungus cake method and double dilution method. The seven Zingiberaceae plants exhibited characteristic antibacterial activities against pathogenic bacteria and fungi. At a 1.5 mg mL−1, A. zerumbet root and rhizome extracts exhibited strong inhibitory activity against S. aureus and E. coli, with 83.23% and 79.62%, respectively. In addition, A. zerumbet leaf and stem extracts had an inhibitory rate of 90.85% against P. aeruginosa. At the same concentration, the leaf and stem, root and rhizome extracts of A. katsumadai had the best antibacterial effect against F. oxysporum, with inhibition rates of 84.46% and 84.73%, respectively. Moreover, A. katsumadai and A. zerumbet leaf and stem extracts had the most significant antibacterial effect against S. aureus, with a MIC of 0.063 mg mL−1 . Thus, both A. katsumadai and A. zerumbet extracts had significant antibacterial activity. In addition, by comparing the inhibitory effect of extracts from different parts, it was found that the inhibitory rate and average inhibitory rate of extracts from leaf and stem were higher than those from root and rhizome. The chemical constituents of A. katsumadai and A. zerumbet, determined by the high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), revealed that citric acid (CA), alpinetin, and pinocembrin (PNCB) were the functional constituents yielding the antibacterial activity. Overall, A. katsumadai and A. zerumbet have the potential to be developed as new plant fungicides and bactericides.

Identification, biological characterization, and fungicide screening of pathogens causing leaf spot of Belamcanda chinensis

The leaf spot of Belamcanda chinensis often appears in May to June and spreads rapidly during the flowering stage(July to September) in the cultivation fields, seriously affecting the yield and quality of B. chinensis. To identify and characterize the pathogens of the leaf spot, we isolated two species of Alternaria, identified them according to Koch's postulates, and tested their pathogenicity and biological characteristics. Furthermore, we determined the inhibitory effects of 6 chemical fungicides, 1 plant fungicide, and 3 microbial fungicides on the pathogens by using mycelial growth rate and plate confrontation method to select the appropriate control agents. The results showed that the two pathogens causing B. chinensis leaf spot were Alternaria tenuissima and A. alternata. The conidia of A. tenuissima often formed long chains with no or a few branches, while those of A. alternata often formed short branched chains. The optimum growth temperature of both A. tenuissima and A. alternata was 25 ℃. The two pathogens grew well in alkaline environment. The indoor fungicide screening experiments showed that 40% flusilazole had good inhibitory effects on the two pathogens, with the EC_(50) values of 12.42 mg·L~(-1) and 12.78 mg·L~(-1) for A. tenuissima and A. alternata, respectively. The results of this study provide a theoretical basis for the subsequent theoretical research and field control of B. chinensis leaf spot.

Antibacterial mechanism of forsythoside A against Pseudomonas syringae pv. actinidiae

In this study, we investigated the antibacterial mechanism of forsythoside A against the kiwifruit canker pathogen, which provided the theoretical basis for the prevention and control of canker disease and the development of plant-based fungicides. The pathogenic bacteria were isolated from kiwifruit diseased tissues and the specific primers Psa_A1 F2 and Psa_A1 R1 were used for preliminary identification. Four pairs of housekeeping genes, including gapA, gltA, gyrB, and rpoD, were used for polygenic typing identification. The inhibition effect of forsythoside A on Psa was evaluated by the filter paper bacteriostasis method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Psa were determined by the 96-well plate absorbance and colony counts. The changes in Psa biofilm formation, motility, IAA synthesis, iron utilization, and respiratory chain dehydrogenase activity were determined. The Psa morphology was observed by Scanning electron microscope (SEM) and transmission electron microscope (TEM). The expression of some virulence genes was analyzed by qPCR. The results showed that the pathogen was Pseudomonas syringae pv. actinidiae(Psa). The inhibitory effect of forsythoside A on Psa was positively correlated with its concentration. while the MIC and MBC were 2.0 and 5.0 mg/mL, respectively. The biofilm formation and motility of Psa were not only obviously inhibited, but also the substance and energy metabolism were interfered, while obvious deformity and rupture of the cells were occurred in Psa Bacteria. In addition, The transcription of the Psa pathogenic genes was affected. The infection investigation of kiwifruit leaves indicated that forsythiaside A inhibits Psa pathogenicity and had a protective effect. This study concluded that forsythoside A has a certain control effect on kiwifruit canker, and has the potentiality to be developed as a novel plant fungicide.

Control of pathogenic fungi on Panax notoginseng by volatile oils from the food ingredients Allium sativum and Foeniculum vulgare.

To screen natural drugs with strong inhibitory effects against pathogenic fungi related to P. notoginseng, the antifungal activities of garlic and fennel EOs were studied by targeting P. notoginseng disease-associated fungi, and the possible action mechanisms of garlic and fennel EOs as plant fungicides were preliminarily discussed. At present, the antifungal mechanism of EOs has not been fully established. Therefore, understanding the antifungal mechanism of plant EOs is helpful to address P. notoginseng diseases continuous cropping disease-related obstacles and other agricultural cultivation problems. First, the Oxford cup method and chessboard were used to confirm that the EOs and oxamyl had a significant inhibitory effect on the growth of Fusarium oxysporum. F. oxysporum is the main pathogen causing root rot of P. notoginseng and the preliminary study on the antifungal mechanisms of the EOs against F. oxysporum showed that the inhibition of EOs mainly affects cell membrane permeability and cell processes and affects the enzyme activities of micro-organism, to achieve antifungal effects. Finally, an invivo model verified that both two EOs could significantly inhibit the occurrence of root rot caused by F. oxysporum.

Biochemical compounds and stress markers in lettuce upon exposure to pathogenic Botrytis cinerea and fungicides inhibiting oxidative phosphorylation

Main conclusionBotrytis cinerea and fungicides interacted and influenced selected biochemical compounds. DPPH and glutathione are the first line of defence against biotic/abiotic stress. Plant metabolites are correlated with fungicides level during dissipation.Botrytis cinerea is an etiological agent of gray mould in leafy vegetables and is combated by fungicides. Fluazinam and azoxystrobin are commonly used fungicides, which inhibit oxidative phosphorylation in fungi. In this study, lettuce was (i) inoculated with B. cinerea; (ii) sprayed with azoxystrobin or fluazinam; (iii) inoculated with B. cinerea and sprayed with fungicides. This investigation confirmed that B. cinerea and fungicides affected lettuce’s biochemistry and stress status. B. cinerea influenced the behaviour of fungicides reflected by shortened dissipation of azoxystrobin compared to non-inoculated plants, while prolonged degradation of fluazinam. Stress caused by B. cinerea combined with fungicides reduced level of chlorophylls (53.46%) and carotenoids (75.42%), whereas increased phenolic compounds (81%), ascorbate concentrations (32.4%), and catalase activity (116.1%). Abiotic stress caused by fungicides contributed most to the induction of carotenoids (107.68 µg g−1 on dissipation day 3−1). Diphenyl picrylhydrazyl (DPPH) radical scavenging activity and glutathione concentration peaked from the first hour of fungicides dissipation. For the first time correlation between the status of plant metabolites and fungicides during their dissipation was observed. These results indicate that non-enzymatic antioxidants could be the first-line compounds against stress factors, whereas ascorbate and antioxidant enzymes tend to mitigate stress only secondarily. The findings of this study help better understand plant biochemistry under biotic/abiotic stress conditions.

Chemical Constituents of the Essential oil from Cuminum cyminum L. and Its Antifungal Activity against Panax notoginseng Pathogens.

Cuminum cyminum L. (Cumin) is a flavoring agent that is commonly used worldwide, and is rich in essential oil. Essential oils (Eos) have been intensively investigated in regard to their potential for disease control in plants, which is provided a chance for the blossom of green pesticides. The chemical components of Cumin essential oil (CEO) were revealed by GC/MS, such as cuminaldehyde (44.53 %), p-cymene (12.14 %), (-)-β-pinene (10.47 %) and γ-terpinene (8.40 %), and found they can inhibit the growth of P. notoginseng-associated pathogenic fungi in vitro and the inhibitory effect of cuminaldehyde was similar to that of hymexazol. SEM and TEM images demonstrated that cuminaldehyde and CEO increased cell permeability and disrupted membrane integrity. The expression of disease-related genes of Fusarium oxysporum showed that CEO induced the expression of most genes, which disrupted biosynthesis, metabolism and signaling pathways. These studies verified the potential of CEO as a plant fungicide that is environmentally friendly and provided ideas for developing new products for controlling root diseases that affect P. notoginseng.

WITHDRAWN: Adjuvants in the spraying of fungicides in soybean plants

Abstract Adjuvant is a substance without phytosanitary properties, added to the spray carrier to increase the efficiency of application technology. Our objective was to determine the best option of combining fungicides and adjuvants to control soybean (Glycine max) leaf diseases, in three crops. The experiment was developed in the Campos Gerais region (PR - Brazil). The five treatments consisted of: 1) control (without fungicide application on soybean plants); 2) fungicide application on soybean plants without adjuvant; 3) fungicide with adjuvant based on mineral oil; 4) fungicide with adjuvant based on lecithin and 5) propionic acid and fungicide with 50% of the dose of adjuvant based on mineral oil + 50% of the dose of surfactant adjuvant based on lecithin and propionic acid. The analyzed variables were physicochemical characteristics of the spray carrier, incidence and severity of diseases and the yield components. A completely randomized design was used to study the physicochemical characteristics of the carrier and in randomized blocks for the field experiment. We used five replicates per treatment. No foaming and mixing incompatibility of the spray carrier was observed for all treatments. The adjuvant based on lecithin and propionic acid further acidified the spray carrier and presented the same surface tension as mineral oil. The soybean plants that did not receive chemical treatment had a higher occurrence of diseases, which reduced the productive potential. The addition of adjuvants to the spray carrier did not increase the performance of fungicides in controlling diseases and did not affect the yield components.

Bullous Lesions on the Foot of a Gardener

A 30-year-old male gardener presented to the emergency department because of painful bullous lesions on his right foot. He reported that the day before he had used a plant fungicide for the first time, which spilled on his right foot multiple times. Notably, the fungicide contained sulfur and copper hydroxychloride (Cu2(OH)3Cl). The foot had started becoming extremely painful and pruritic at night, and then he woke up with bullae on the skin.

Supramolecular Nanoplatform Based on Mesoporous Silica Nanocarriers and Pillararene Nanogates for Fungus Control.

Synthetic fungicides have been widely used to protect crops from fungal diseases. However, excessive use of synthetic fungicides leads to the generation of fungicide resistance in fungal pathogens. Recently, smart cargo delivery systems have been introduced for the construction of a pesticide delivery nanoplatform, benefiting from their controlled release performance. Herein, a fungal pathogen microenvironment-responsive supramolecular fungicide nanoplatform has been designed and constructed, using quaternary ammonium salt (Q)-modified mesoporous silica nanoparticles (MSN-Q NPs) as nanocarriers loaded with berberine hydrochloride (BH) and carboxylatopillar[5]arene (CP[5]A) as nanogates to form BH-loaded CP[5]A@MSN-Q NPs for effective inhibition of Botrytis cinerea. CP[5]A as nanogates can endow the fungicide nanoplatform with pH stimuli-responsive release features for the control of fungicide release. The loaded BH, as a natural plant fungicide, provides an ecofriendly alternative to synthetic fungicides for controlling B. cinerea. Interestingly, we use oxalic acid (OA) secreted by B. cinerea as a trigger so that BH can be released from the fungicide nanoplatform on demand under pathogen microenvironments for controlling B. cinerea. The experimental results indicate that the fabricated fungicide nanoplatform could effectively inhibit the mycelial growth and spore germination, providing a new way for the management of B. cinerea in actual application.

Pine Rosin as a Valuable Natural Resource in the Synthesis of Fungicide Candidates for Controlling Fusarium oxysporum on Cucumber.

To improve the effect of pine rosin in plant fungicides, four series of dehydroabietyl-1,3,4-thiadiazole derivatives from the natural product rosin were synthesized. Based on the evaluation of the in vitro antifungal activity against Sclerotinia sclerotiorum, Botrytis cinerea, Fusarium oxysporum, and Magnaporthe oryzae, rosin-based 1,3,4-thiadiazole compounds containing thiophene heterocycles were screened. Notably, compound 3e [dehydroabietyl-(1,3,4-thiadiazol-2-yl)-5-nitrothiophene-2-carboxamide] exhibited excellent antifungal property against F. oxysporum with an EC50 of 0.618 mg/L, which was lower than that of the positive control carbendazim (0.649 mg/L). The in vivo antifungal activity results showed that 3e exerted a protective effect on cucumber plants. Physiological and biochemical studies showed that the primary mechanism of action of compound 3e on F. oxysporum was it changed the mycelial morphology, increased the cell membrane permeability, and inhibited the synthesis of ergosterol in the mycelia. Furthermore, the quantitative structure-activity relationship studies revealed that the frontier orbital energy in the molecule had a key role in the antifungal activity through the conjugation and electrostatic interaction between compound 3e and the receptors of the target. Thus, the present study highlighted the application of rosin-based fungicidal candidates and exploited efficient plant pesticides for sustainable crop production.

Study on Antifungal Activity and Ability Against Rice Leaf Blast Disease of Nano Cu-Cu2O/Alginate

Background: Rice blast disease due to Pyricularia oryzae fungus is one of the most destructive ones for rice, causing serious losses in yield and quality in Vietnam and other countries. Studying to develop new fungicides to control the fungal disease effectively is essential.Methods: The sodium alginate-stabilized Cu-Cu2O nanocolloidal solution with a size of about 4 nm and the Cu concentration of 5,000 mg/L was prepared by chemical method. The antifungal activity in vitro against P. oryzae and the ability to control the rice blast disease in the greenhouse of nano Cu-Cu2O/alginate were assessed.Result: The nano Cu-Cu2O/alginate exhibited highly fungal activity with the IC50 of 17.8 mg Cu /L. The disease severity of nano Cu-Cu2O/alginate treatments was in the range of 9.38 - 18.54% in comparison with 47.57% of the untreated control. The grain yield of rice plants treated with nano Cu-Cu2O/alginate increased compared with that of the untreated control, and the Cu content in polished rice was almost the same as that of usually cultured polished rice. Thus, the nano Cu-Cu2O/alginate can be used in agriculture as a plant fungicide, especially for rice cultivation.

Facile and green synthesis of 4,6-dimethoxy-2-methylsulfonylpyrimidine using chloromethane as methylating agent

ABSTRACT 4,6-dimethoxy-2-methylsulfonylpyrimidine (DMSP) is an important chemical intermediate which has been widely used in the synthesis of plant growth regulators, pesticides, and fungicides. However, the traditional synthetic manufacturing process involves highly toxic dimethylsulfate and highly corrosive phosphorus oxychloride, causing serious environmental problems. To overcome these problems, we utilized chloromethane instead of dimethylsulfate as a methylating agent to synthesize DMSP. The reaction was shortened to only2 steps. Since 4,6-dimethoxy-2-methylthiopyrimidine is the key intermediate in the synthesis of DMSP, it is of great importance to improve the conversion and selectivity. In this work, 4,6-dimethoxy-2-methylthiopyrimidine was synthesized from 2-thiobarbituric acid in the presence of potassium carbonate and chloromethane through a one-step procedure. By optimization of reaction conditions, high conversion of 2-thiobarbituric acid (85.7%) and selectivity of 4,6-dimethoxy-2-methyl thiopyrimidine (53.1%) were obtained. Compared to the traditional synthetic pathway, our new synthetic process is more economical and environment-friendly.