Design, Synthesis, Antifungal Activity, and 3D-QSAR Study of Novel Quinoxaline-2-Oxyacetate Hydrazide.

Plant pathogenic fungi pose a major threat to global food security, ecosystem services, and human livelihoods. Effective and broad-spectrum fungicides are needed to combat these pathogens. In this study, a novel antifungal 2-oxyacetate hydrazide quinoxaline scaffold as a simple analogue was designed and synthesized. Their antifungal activities were evaluated against Botrytis cinerea (B. cinerea), Altemaria solani (A. solani), Gibberella zeae (G. zeae), Rhizoctonia solani (R. solani), Colletotrichum orbiculare (C. orbiculare), and Alternaria alternata (A. alternata). These results demonstrated that most compounds exhibited remarkable inhibitory activities and possessed better efficacy than ridylbacterin, such as compound 15 (EC50 = 0.87 µg/mL against G. zeae, EC50 = 1.01 µg/mL against C. orbiculare) and compound 1 (EC50 = 1.54 µg/mL against A. alternata, EC50 = 0.20 µg/mL against R. solani). The 3D-QSAR analysis of quinoxaline-2-oxyacetate hydrazide derivatives has provided new insights into the design and optimization of novel antifungal drug molecules based on quinoxaline.

Discovery of a Biocontrol Strain Trichaptum laricinum: Its Metabolites and Antifungal Activity against Pathogenic Fungus Colletotrichum anthrisci.

Finding safe and environmentally friendly fungicides is one of the important strategies in modern pesticide research and development. In this work, the antipathogenic effects of the fungus Trichaptum laricinum against the anthracnose pathogen Colletotrichum anthrisci were studied. The EtOAc extract of T. laricinum showed remarkable antifungal activity against C. anthrisci with an inhibition rate of 50% at 256 µg/mL. Bioguided isolation of the cultural broth of T. laricinum produced four new drimane sesquiterpenes, trichalarins A-D (1-4), and six other metabolites (5-10). Their structures were established by extensive spectroscopic methods, quantum chemical calculations, and single-crystal X-ray diffraction. All compounds exhibited antifungal activity against C. anthrisci with minimum inhibitory concentrations (MICs) of 8-64 µg/mL in vitro. Further in vivo assay suggested that compounds 2, 6, and 9 could significantly inhibit C. anthrisci growth in avocado fruit with inhibition rates close to 80% at the concentration of 256 µg/mL, while compounds 2 and 6 had an inhibition rate over 90% at the concentration of 512 µg/mL. The EtOAc extract of T. laricinum had no inhibitory effect on Pinus massoniana seed germination and growth at the concentration of 2 mg/mL, showing good environmental friendliness. Thus, the fungus T. laricinum could be considered as an ideal biocontrol strain, and its metabolites provided a diverse material basis for the antibiotic agents.

Design and Synthesis of Eugenol Derivatives Bearing a 1,2,3-Triazole Moiety for Papaya Protection against Colletotrichum gloeosporioides.

A series of 19 novel eugenol derivatives containing a 1,2,3-triazole moiety was synthesized via a two-step process, with the key step being a copper(I)-catalyzed azide-alkyne cycloaddition reaction. The compounds were assessed for their antifungal activities against Colletotrichum gloeosporioides, the causative agent of papaya anthracnose. Triazoles 2k, 2m, 2l, and 2n, at 100 ppm, were the most effective, reducing mycelial growth by 88.3, 85.5, 82.4, and 81.4%, respectively. Molecular docking calculations allowed us to elucidate the binding mode of these derivatives in the catalytic pocket of C. gloeosporioides CYP51. The best-docked compounds bind closely to the heme cofactor and within the channel access of the lanosterol (LAN) substrate, with crucial interactions involving residues Tyr102, Ile355, Met485, and Phe486. From such studies, the antifungal activity is likely attributed to the prevention of substrate LAN entry by the 1,2,3-triazole derivatives. The triazoles derived from natural eugenol represent a novel lead in the search for environmentally safe agents for controlling C. gloeosporioides.

Suppression of anthracnose disease by orsellinaldehyde isolated from the mushroom Coprinus comatus.

AIMS: Anthracnose caused by Colletotrichum species is one of the most devastating diseases of fruits and crops. We isolated and identified an antifungal compound from the mushroom Coprinus comatus and investigated its inhibitory potential against anthracnose disease-causing fungi with the goal of discovering natural products that can suppress anthracnose-caused plant disease. METHODS AND RESULTS: The culture filtrate of C. comatus was subjected to a bioassay-guided isolation of antifungal compounds. The active compound was identified as orsellinaldehyde (2,4-dihydroxy-6-methylbenzaldehyde) based on mass spectroscopy and nuclear magnetic resonance analyses. Orsellinaldehyde displayed broad-spectrum inhibitory activity against different plant pathogenic fungi. Among the tested Colletotrichum species, it exhibited the lowest IC50 values on conidial germination and germ tube elongation of Colletotrichum orbiculare. The compound also showed remarkable inhibitory activity against Colletotrichum gloeosporiodes. The staining of Colletotrichum conidia with fluorescein diacetate and propidium iodide demonstrated that the compound is fungicidal. The postharvest in-vivo detached fruit assay indicated that orsellinaldehyde suppressed anthracnose lesion symptoms on mango and cucumber fruits caused by C. gloeosporioides and C. orbiculare, respectively. CONCLUSIONS: Orsellinaldehyde was identified as a potent antifungal compound from the culture filtrate of C. comatus. The inhibitory and fungicidal activities of orsellinaldehyde against different Colletotrichum species indicate its potential as a fungicide for protecting various fruits against anthracnose disease-causing fungi.

Antifungal activity of bio-active cell-free culture extracts and volatile organic compounds (VOCs) synthesised by endophytic fungal isolates of Garden Nasturtium.

Antimicrobial resistance in fungal pathogens (both human and plant) is increasing alarmingly, leading to massive economic crises. The existing anti-fungal agents are becoming ineffective, and the situation worsens on a logarithmic scale. Novel antifungals from unique natural sources are highly sought to cope sustainably with the situation. Metabolites from endophytic microbes are the best-fitted alternatives in this case. Endophytes are the untapped sources of 'plants' internal microbial population' and are promising sources of effective bio-therapeutic agents. Fungal endophytes were isolated from Tropaeolum majus and checked for antifungal activity against selected plant and human pathogens. Bioactive metabolites were identified through chromatographic techniques. The mode of action of those metabolites was evaluated through various spectroscopic techniques. The production of antifungal metabolite was optimized also. In particular VOCs (volatile organic compounds) of TML9 were tested in vitro for their anti-phytopathogenic activity. Ethyl acetate (EA) extract of cell-free culture components of Colletotrichum aenigma TML3 exhibited broad-spectrum antifungal activity against four species of Candida and the major constituents reported were 6-pentyl-2H-pyran-2-one, 2-Nonanone, 1 propanol 2-amino. The volatile metabolites, trans-ocimene, geraniol, and 4-terpinyl acetate, produced from Curvularia lunata TML9, inhibited the growth of some selected phyto pathogens. EA extract hampered the biofilm formation, minimised the haemolytic effect, and blocked the transformation of Candida albicans (MTCC 4748) from yeast to hyphal form with a Minimum Fungicidal Concentration (MFC) of 200-600 µg mL-1. Central carbohydrate metabolism, ergosterol synthesis, and membrane permeability were adversely affected and caused the lethal leakage of necessary macromolecules of C. albicans. Volatile metabolites inhibited the growth of phytopathogens i.e., Rhizoctonia solani, Alternaria alternata, Botrytis cinerea, Cercospora beticola, Penicillium digitatum, Aspergillus fumigatus, Ceratocystis ulmi, Pythium ultimum up to 89% with an IC50 value of 21.3-69.6 µL 50 mL-1 and caused leakage of soluble proteins and other intracellular molecules. Citrusy sweet odor volatiles of TML9 cultured in wheat-husk minimised the infections of Penicillium digitatum (green mold), in VOC-exposed sweet oranges (Citrus sinensis). Volatile and non-volatile antifungal metabolites of these two T. majus endophytes hold agricultural and pharmaceutical interests. Metabolites of TML3 have strong anti-Candida activity and require further assessment for therapeutic applications. Also, volatile metabolites of TML9 can be further studied as a source of antifungals. The present investigational outcomes bio-prospects the efficacy of fungal endophytes of Garden Nasturtium.

3D-QSAR-Directed Synthesis of Halogenated Coumarin-3-Hydrazide Derivatives: Unveiling Their Potential as SDHI Antifungal Agents.

The pursuit of new succinate dehydrogenase (SDH) inhibitors is a leading edge in fungicide research and development. The use of 3D quantitative structure-activity relationship (3D-QSAR) models significantly enhances the development of compounds with potent antifungal properties. In this study, we leveraged the natural product coumarin as a molecular scaffold to synthesize 74 novel 3-coumarin hydrazide derivatives. Notably, compounds 4ap (0.28 µg/mL), 6ae (0.32 µg/mL), and 6ah (0.48 µg/mL) exhibited exceptional in vitro effectiveness against Rhizoctonia solani, outperforming the commonly used fungicide boscalid (0.52 µg/mL). Furthermore, compounds 4ak (0.88 µg/mL), 6ae (0.61 µg/mL), 6ah (0.65 µg/mL), and 6ak (1.11 µg/mL) showed significant activity against Colletotrichum orbiculare, surpassing both the SDHI fungicide boscalid (43.45 µg/mL) and the broad-spectrum fungicide carbendazim (2.15 µg/mL). Molecular docking studies and SDH enzyme assays indicate that compound 4ah may serve as a promising SDHI fungicide. Our ongoing research aims to refine this 3D-QSAR model further, enhance molecular design, and conduct additional bioactivity assays.

Design, Synthesis, Bioactive Evaluation, and Molecular Dynamics Simulation of Novel 4H-Pyrano[3,2-c]pyridine Analogues as Potential Sterol 14α-Demethylase (CYP51) Inhibitors.

To discover potential sterol 14α-demethylase (CYP51) inhibitors, thirty-four unreported 4H-pyrano[3,2-c]pyridine derivatives were designed and synthesized. The assay results indicated that most compounds displayed significant fungicidal activity against Sclerotinia sclerotiorum, Colletotrichum lagenarium, Botrytis cinerea, Penicillium digitatum, and Fusarium oxysporum at 16 µg/mL. The half maximal effective concentration (EC50) values of compounds 7a, 7b, and 7f against B. cinerea were 0.326, 0.530, and 0.610, respectively. Namely, they had better antifungal activity than epoxiconazole (EC50 = 0.670 µg/mL). Meanwhile, their half maximal inhibitory concentration (IC50) values against CYP51 were 0.377, 0.611, and 0.748 µg/mL, respectively, representing that they also possessed better inhibitory activities than epoxiconazole (IC50 = 0.802 µg/mL). The fluorescent quenching tests of proteins showed that 7a and 7b had similar quenching patterns to epoxiconazole. The molecular dynamics simulations indicated that the binding free energy of 7a and epoxiconazole to CYP51 was -35.4 and -27.6 kcal/mol, respectively.

Antifungal Pseuboyenes A-J, Bergamotene-Derived Sesquiterpenoids from a Cold-Seep-Derived Pseudallescheria boydii.

A chemical investigation of a cold-seep-sediment-derived fungus, Pseudallescheria boydii CS-793, resulted in characterization of 10 novel bergamotene-derived sesquiterpenoids, pseuboyenes A-J (1-10). Their structures were elucidated by spectroscopic and X-ray crystallographic analyses as well as using the modified Mosher's method. Compound 1 represents the first example of a ß-bergamotene containing a 6-oxobicyclo[3.2.1]octane nucleus adducted with a methyl lactate unit, while 8-10 involve a skeletal rearrangement from bergamotene. Compounds 2-5 showed significant antifungal activities against Colletotrichum gloeosporioides Penz. and Fusarium oxysporum with MICs ranging from 0.5 to 8 µg/mL. Compound 4 exhibited an in vitro anti-F. proliferatum effect with an EC50 value of 1.0 µg/mL.

The CsPbs2-interacting protein oxalate decarboxylase CsOxdC3 modulates morphosporogenesis, virulence, and fungicide resistance in Colletotrichum siamense.

The HOG MAPK pathway mediates diverse cellular and physiological processes, including osmoregulation and fungicide sensitivity, in phytopathogenic fungi. However, the molecular mechanisms underlying HOG MAPK pathway-associated stress homeostasis and pathophysiological developmental events are poorly understood. Here, we demonstrated that the oxalate decarboxylase CsOxdC3 in Colletotrichum siamense interacts with the protein kinase kinase CsPbs2, a component of the HOG MAPK pathway. The expression of the CsOxdC3 gene was significantly suppressed in response to phenylpyrrole and tebuconazole fungicide treatments, while that of CsPbs2 was upregulated by phenylpyrrole and not affected by tebuconazole. We showed that targeted gene deletion of CsOxdC3 suppressed mycelial growth, reduced conidial length, and triggered a marginal reduction in the sporulation characteristics of the ΔCsOxdC3 strains. Interestingly, the ΔCsOxdC3 strain was significantly sensitive to fungicides, including phenylpyrrole and tebuconazole, while the CsPbs2-defective strain was sensitive to tebuconazole but resistant to phenylpyrrole. Additionally, infection assessment revealed a significant reduction in the virulence of the ΔCsOxdC3 strains when inoculated on the leaves of rubber tree (Hevea brasiliensis). From these observations, we inferred that CsOxdC3 crucially modulates HOG MAPK pathway-dependent processes, including morphogenesis, stress homeostasis, fungicide resistance, and virulence, in C. siamense by facilitating direct physical interactions with CsPbs2. This study provides insights into the molecular regulators of the HOG MAPK pathway and underscores the potential of deploying OxdCs as potent targets for developing fungicides.

Antimicrobial properties of unusual eremophilanes from the endophytic Diaporthe sp. BCC69512.

Six undescribed infrequent eremophilane derivatives including diaportheremopholins A - F and its previously undescribed side chain (E)-2-methyloct-2-enoic acid, together with three known compounds (testacein, xestodecalactones B and C), were isolated from the endophytic fungus Diaporthe sp. BCC69512. The chemical structures were determined based on NMR spectroscopic information in conjunction with the evidence from NOESY spectrum, Mosher's application, and chemical reactions for corroborating the absolute configurations. The isolated compounds were evaluated for biological properties such as antimalarial, anti-TB, anti-phytopathogenic fungal, antibacterial activities and for cytotoxicity against malignant (MCF-7 and NCI-H187) and non-malignant (Vero) cells. Diaportheremopholins B (2) and E (5) possessed broad antimicrobial activity against Mycobacterium tuberculosis, Bacillus cereus, Alternaria brassicicola and Colletotrichum acutatum with MICs in a range of 25.0-50.0 µg/mL. Testacein (7) exhibited strong anti-A. brassicicola and anti-C. acutatum activities with equal MIC values of 3.13 µg/mL. Moreover, diaportheremopholin F (6) and compound 8 displayed antitubercular activity with equal MIC values of 50.0 µg/mL. All tested compounds were non-cytotoxic against MCF-7, NCI-H187, and Vero cells, except those compounds 2 and 5-7 exhibited weak cytotoxicity against both malignant and non-malignant cells with IC50 values in a range of 15.5-115.5 µM.

Enhanced antifungal properties of poly(butylene succinate) film with lignin nanoparticles and trans-cinnamaldehyde for mango packaging.

Sustainable poly(butylene succinate) (PBS) films incorporating lignin nanoparticles (LN) and trans-cinnamaldehyde (CN) have been developed to preserve mango freshness and provide food safety. PBS/LN, PBS/CN, and PBS/LN/CN composite films were produced by blown film melt extrusion. This study investigated the effect of CN-LN on the CN remaining content, thermal, mechanical, and barrier properties, diffusion coefficient, and antifungal activity of PBS films both in vitro and in vivo. Results showed that LN in the PBS/LN/CN composite film contained more CN than in the PBS/CN film. The compatibility of CN-LN with PBS produced homogeneous surfaces with enhanced barrier properties. PBS/LN/CN composite films demonstrated superior antifungal efficacy, inhibiting the growth of Colletotrichum gloeosporioides and preserving mango quality during storage. Results suggested that incorporating LN into PBS composite films prolonged the sustained release of antifungal agents, thereby inhibiting microbial growth and extending the shelf life of mangoes. Development of PBS/LN/CN composite films is a beneficial step toward reducing food waste and enhancing food safety.

Four New Isocoumarins from the Mangrove Fungus Alternaria Malorum with Antimicrobial Activities.

Four new isocoumarins, alternariethers A-C (1-3) and alternariester (4) were separated from the fermentation of the fungus Alternaria malorum FL39, purified from Myoporum bontioides. Their structures were ascertained using NMR and HR-ESI-MS spectroscopy. For compound 4, the absolute configuration was solved with the help of ECD calculation and the DP4+ method. Compared with the positive control triadimefon, compound 1 showed more potent antifungal effects on Colletotrichum musae. The antifungal effects of compounds 1, 2, and 3 on Fusarium oxysporum and Fusarium graminearum, of compound 4 on F. oxysporum, were equal to those of triadimefon. Except for compound 4 which was inactive against Escherichia coli with O78 serotype, all compounds showed moderate or weak antibacterial activity against Staphylococcus aureus ATCC 6538 and E. coli with O6 or O78 serotype.

Defensin-like peptides from Capsicum chinense induce increased ROS, loss of mitochondrial functionality, and reduced growth of the fungus Colletotrichum scovillei.

In the present study, we identified and characterized two defensin-like peptides in an antifungal fraction obtained from Capsicum chinense pepper fruits and inhibited the growth of Colletotrichum scovillei, which causes anthracnose. AMPs were extracted from the pericarp of C. chinense peppers and subjected to ion exchange, molecular exclusion, and reversed-phase in a high-performance liquid chromatography system. We investigated the endogenous increase in reactive oxygen species (ROS), the loss of mitochondrial functioning, and the ultrastructure of hyphae. The peptides obtained from the G3 fraction through molecular exclusion chromatography were subsequently fractionated using reverse-phase chromatography, resulting in the isolation of fractions F1, F2, F3, F4, and F5. The F1-Fraction suppressed C. scovillei growth by 90, 70.4, and 44% at 100, 50, and 25 µg mL-1, respectively. At 24 h, the IC50 and minimum inhibitory concentration were 21.5 µg mL-1 and 200 µg mL-1, respectively. We found an increase in ROS, which may have resulted in an oxidative burst, loss of mitochondrial functioning, and cytoplasm retraction, as well as an increase in autophagic vacuoles. MS/MS analysis of the F1-Fraction indicated the presence of two defensin-like proteins, and we were able to identify the expression of three defensin sequences in our C. chinense fruit extract. The F1-Fraction was also found to inhibit the activity of insect α-amylases. In summary, the F1-Fraction of C. chinense exhibits antifungal activity against a major pepper pathogen that causes anthracnose. These defensin-like compounds are promising prospects for further research into antifungal and insecticide biotechnology applications. © 2024 Society of Chemical Industry.

Penicilloneines A and B, Quinolone-Citrinin Hybrids from a Starfish-Derived Penicillium sp.

Penicilloneines A (1) and B (2) are the first reported quinolone-citrinin hybrids. They were isolated from the starfish-derived fungus Penicillium sp. GGF16-1-2, and their structures were elucidated using spectroscopic, chemical, computational, and single-crystal X-ray diffraction methods. Penicilloneines A (1) and B (2) share a common 4-hydroxy-1-methyl-2(1H)-quinolone unit; however, they differ in terms of citrinin moieties, and these two units are linked via a methylene bridge. Penicilloneines A (1) and B (2) exhibited antifungal activities against Colletotrichum gloeosporioides, with lethal concentration 50 values of 0.02 and 1.51 µg/mL, respectively. A mechanistic study revealed that 1 could inhibit cell growth and promote cell vacuolization and consequent disruption of the fungal cell walls via upregulating nutrient-related hydrolase genes, including putative hydrolase, acetylcholinesterase, glycosyl hydrolase, leucine aminopeptidase, lipase, and beta-galactosidase, and downregulating their synthase genes 3-carboxymuconate cyclase, pyruvate decarboxylase, phosphoketolase, and oxalate decarboxylase.

Utilizing Disease Prediction Models to Time Fungicide Applications for Controlling Ripe Rot, Caused by Colletotrichum spp., in Maryland Vineyards.

Two previously published ripe rot prediction models, DF2-NN and GH2-DT, were evaluated for fungicide application timing efficacy in Maryland vineyards. Both models utilize leaf wetness duration (LWD), temperature, and grape cluster phenological stages as model parameters. These three parameters were tracked throughout the 2021 to 2023 seasons in three vineyards. The fungicide efficacy trials started at the veraison phenological stage and included a nontreated control, a 12-day interval treatment, and two model-triggered treatments when risk predicted by the models crossed a threshold. The severity of ripe rot on the clusters in each treatment was assessed when the fruit were mature. Ripe rot severity in the nontreated controls was higher during seasons with more LWD and more precipitation. Days in which the models were triggered by the environmental conditions primarily coincided with precipitation events and lengthy LWDs. The model-triggered treatments never had significantly higher ripe rot severity than the 12-day interval treatment but had significantly lower severities than the nontreated control in most trials which had high ripe rot pressure. Furthermore, the model-triggered treatments resulted in fewer fungicide applications than the 12-day interval treatment on average. The DF2-NN model appeared to be more accurate and useful for ripe rot prediction and treatment than the GH2-DT model because it triggered fewer fungicide applications while reducing ripe rot. This model may be useful for improving or maintaining ripe rot control with fewer fungicide inputs, which may be beneficial for the environment and the reduction of fungicide resistance selection.

Formulation of the biological control yeast Meyerozyma caribbica by electrospraying process: effect on postharvest control of anthracnose in mango (Mangifera indica L.) and papaya (Carica papaya L.).

BACKGROUND: Microorganism for biological control of fruit diseases is an eco-friendly alternative to the use of chemical fungicides. RESULTS: This is the first study evaluating the electrospraying process to encapsulate the biocontrol yeast Meyerozyma caribbica. The effect of encapsulating material [Wey protein concentrate (WPC), Fibersol® and Trehalose], its concentration and storage temperature on the cell viability of M. caribbica, and in vitro and in vivo control of Colletotrichum gloeosporioides was evaluated. The processing with commercial resistant maltodextrin (Fibersol®) 30% (w/v) as encapsulating material showed the highest initial cell viability (95.97 ± 1.01%). The storage at 4 ± 1 °C showed lower losses of viability compared to 25 ± 1 °C. Finally, the encapsulated yeast with Fibersol 30% w/v showed inhibitory activity against anthracnose in the in vitro and in vivo tests, similar to yeast fresh cells. CONCLUSION: Electrospraying was a highly efficient process due to the high cell viability, and consequently, a low quantity of capsules is required for the postharvest treatment of fruits. Additionally, the yeast retained its antagonistic power during storage. © 2021 Society of Chemical Industry.

Synthesis and in vitro antifungal activity of new Michael-type amino derivatives of xanthatin, a natural sesquiterpene lactone from Xanthium strumarium L.

Structural optimization using plant secondary metabolites as templates is one of the important approach to discover pesticide molecules with novel skeletons. Xanthatin, a natural sesquiterpene lactone isolated from the Xanthium plants (Family: Compositae), exhibits important biological properties. In this work, a series of Michael-type amino derivatives were prepared from xanthatin and their structures were characterized by 1H NMR, 13C NMR and HR-MS, and their antifungal activities against several phytopathogenic fungi were evaluated according to the spore germination method and mycelium growth rate method in vitro. The results illustrated that compounds 2g (IC50 = 78.91 µg/mL) and 2o (IC50 = 64.51 µg/mL) exhibited more promising inhibition activity against spores of F. solani than precursor xanthatin, compounds 2g, 2l, and 2r exhibited remarkable antifungal effect on C. mandshurica with the average inhibition rates (AIRs) >90%, whereas the AIR of xanthatin was only 59.34%. Meanwhile, the preliminary structure-activity relationships suggested that the amino containing 2-methoxyethyl or 4-chlorophenylmethyl group appended in the C-13 position of xanthatin could yield potential compounds against fungal spores, and the exocyclic double bond of xanthatin is essential to maintain its mycelial growth inhibitory activity. Therefore, the aforementioned findings indicate that partial xanthatin amino-derivatives could be considered for further exploration as the potential lead structures toward development of the new environmentally friendly fungicidal candidates for sustainable crop protection.

Fruit juice mediated multicomponent reaction for the synthesis of substituted isoxazoles and their in vitro bio-evaluation.

A simple, efficient and eco-friendly procedure for the synthesis of isoxazole derivatives (4a-4h) using one-pot three-component reaction between substituted aldehydes (1a), methyl acetoacetate (2a) and hydroxylamine hydrochloride (3a) has been achieved in presence of Cocos nucifera L. juice, Solanum lycopersicum L. juice and Citrus limetta juice respectively. The homogeneity of synthesized compounds was confirmed by melting point and thin layer chromatography. The synthesized compounds were characterized by using 1H NMR, FTIR and CHN analyses and evaluated for in vitro herbicidal activity against Raphanus sativus L. (Radish seeds). The compounds (4a-4h) were also screened for their fungicidal activity against Rhizoctonia solani and Colletotrichum gloeosporioides. Antibacterial activity was also tested against Erwinia carotovora and Xanthomonas citri. From bio-evaluation data, it was found that compound 4b was most active against Raphanus sativus L. (root) and Raphanus sativus L. (shoot) respectively. Compound 4b was also found most active against both the fungus viz. R. solani and C. gloeosporioides showing maximum percentage growth inhibition i.e. 90.00 against R. solani and 82.45 against C. gloeosporioides at 2000 µg/mL concentration. Compound 4 h has shown maximum inhibition zone i.e. 3.00-9.60 mm against Erwinia carotovora at 2000 µg/mL concentration. Maximum Xanthomonas citri growth was also inhibited by compound 4 h showing inhibition zone 1.00-5.00 mm at highest concentration.

Electrochemical Oxo-Fluorosulfonylation of Alkynes under Air: Facile Access to ß-Keto Sulfonyl Fluorides.

Radical fluorosulfonylation is emerging as an appealing approach for the synthesis of sulfonyl fluorides, which have widespread applications in many fields, in particular in the context of chemical biology and drug development. Here, we report the first investigation of FSO2 radical generation under electrochemical conditions, and the establishment of a new and facile approach for the synthesis of ß-keto sulfonyl fluorides via oxo-fluorosulfonylation of alkynes with sulfuryl chlorofluoride as the radical precursor and air as the oxidant. This electrochemical protocol is amenable to access two different products (ß-keto sulfonyl fluorides or α-chloro-ß-keto sulfonyl fluorides) with the same reactants. The ß-keto sulfonyl fluoride products can be utilized as useful building blocks in the synthesis of various derivatives and heterocycles, including the first synthesis of an oxathiazole dioxide compound. Furthermore, some ß-keto sulfonyl fluorides and derivatives exhibited notably potent activities against Bursaphelenchus xylophilus and Colletotrichum gloeosporioides.

Non-Chemical Treatments for the Pre- and Post-Harvest Elicitation of Defense Mechanisms in the Fungi-Avocado Pathosystem.

The greatest challenge for the avocado (Persea americana Miller) industry is to maintain the quality of the fruit to meet consumer requirements. Anthracnose is considered the most important disease in this industry, and it is caused by different species of the genus Colletotrichum, although other pathogens can be equally important. The defense mechanisms that fruit naturally uses can be triggered in response to the attack of pathogenic microorganisms and also by the application of exogenous elicitors in the form of GRAS compounds. The elicitors are recognized by receptors called PRRs, which are proteins located on the avocado fruit cell surface that have high affinity and specificity for PAMPs, MAMPs, and DAMPs. The activation of defense-signaling pathways depends on ethylene, salicylic, and jasmonic acids, and it occurs hours or days after PTI activation. These defense mechanisms aim to drive the pathogen to death. The application of essential oils, antagonists, volatile compounds, chitosan and silicon has been documented in vitro and on avocado fruit, showing some of them to have elicitor and fungicidal effects that are reflected in the postharvest quality of the fruit and a lower incidence of diseases. The main focus of these studies has been on anthracnose diseases. This review presents the most relevant advances in the use of natural compounds with antifungal and elicitor effects in plant tissues.