Antifungal Effect of Bauhinia variegata Lectin (BvL) on Bipolaris oryzae.

The search for less harmful, ecologically efficient, more specific, and natural alternatives for the control of pathogens is essential. Bauhinia variegata lectin (BvL) is a protein that has numerous biological activities, including antifungal. The present study examines the potential in vitro of B. variegata lectin against the fungus Bipolaris oryzae, responsible for agricultural losses in southern Brazil, due to damage to rice fields during seed germination. Bioassays to assess the inhibition potential of BvL were performed, including fungal growth, spore formation, and germination, in concentrations of 0, 25, 50, and 100 µg mL-1. Only the concentration of 100 µg mL-1 successfully inhibited mycelial growth and spore germination, while in spore formation, all treatments inhibited sporulation. In addition, fluorescence microscopy analysis demonstrated the ability of lectin to bind to the fungus and the lack of detection in the presence of lactose, suggesting its interaction with the fungal cell wall structures. This study highlights the potential of B. variegata seed lectin to control mycelial growth, sporulation, and germination of the phytopathogenic fungus B. oryzae, posing as a new biotechnological possibility for biological control.

Stereoselective Bioactivity and Action Mechanism of the Fungicide Isopyrazam.

Understanding the stereoselective bioactivity of chiral pesticides is crucial for accurately evaluating their effectiveness and optimizing their use. Isopyrazam, a widely used chiral SDHI fungicide, has been studied for its antifungal activity only at the racemic level. Therefore, to clarify the highly bioactive isomers, the stereoselective bioactivity of isopyrazam isomers against four typical phytopathogens was studied for the first time. The bioactivity ranking of the isomers was trans-1S,4R,9R-(+)-isopyrazam > cis-1R,4S,9R-(+)-isopyrazam > trans-1R,4S,9S-(-)-isopyrazam > cis-1S,4R,9S-(-)-isopyrazam. SDH activity was assessed by molecular docking simulation and actual detection to confirm the reasons for stereoselective bioactivity. The results suggest that the stereoselective bioactivity of isopyrazam is largely dependent on the differential binding ability of each isomer to the SDH ubiquitin-binding site, located within a cavity formed by the iron-sulfur subunit, the cytochrome b560 subunit, and the cytochrome b small subunit. Moreover, to reveal the molecular mechanism of isopyrazam stereoselectively affecting mycelial growth, the contents of succinic acid, fumaric acid, and ATP were measured. Furthermore, by measuring exospore polysaccharides and oxalic acid content, it was determined that 1S,4R,9R-(+)- and 1R,4S,9R-(+)-isopyrazam more strongly inhibited the ability of Sclerotinia sclerotiorum to infect plants. The findings provided essential data for the development of high-efficiency isopyrazam fungicides and offered a methodological reference for analyzing the enantioselective activity mechanism of SDHI fungicides.

Discovery of Benzothiazol-2-ylthiophenylpyrazole-4-carboxamides as Novel Succinate Dehydrogenase Inhibitors.

Succinate dehydrogenase (SDH) has been considered an ideal target for discovering fungicides. To develop novel SDH inhibitors, in this work, 31 novel benzothiazol-2-ylthiophenylpyrazole-4-carboxamides were designed and synthesized using active fragment exchange and a link approach as promising SDH inhibitors. The findings from the tests on antifungal activity indicated that most of the synthesized compounds displayed remarkable inhibition against the fungi tested. Compound Ig N-(2-(((5-chlorobenzo[d]thiazol-2-yl)thio)methyl)phenyl)-3-(difluoromethyl)-1-methyl-1H-yrazole-4-carboxamide, with EC50 values against four kinds of fungi tested below 10 µg/mL and against Cercospora arachidicola even below 2 µg/mL, showed superior antifungal activity than that of commercial fungicide thifluzamide, and specifically compounds Ig and Im were found to show preventative potency of 90.6% and 81.3% against Rhizoctonia solani Kühn, respectively, similar to the positive fungicide thifluzamide. The molecular simulation studies suggested that hydrophobic interactions were the main driving forces between ligands and SDH. Encouragingly, we found that compound Ig can effectively promote the wheat seedlings and the growth of Arabidopsis thaliana. Our further studies indicated that compound Ig could stimulate nitrate reductase activity in planta and increase the biomass of plants.

Discovery of a Hybrid Molecule with Phytotoxic Activity by Genome Mining, Heterologous Expression, and OSMAC Strategy.

Genome mining in association with the OSMAC (one strain, many compounds) approach provides a feasible strategy to extend the chemical diversity and novelty of natural products. In this study, we identified the biosynthetic gene cluster (BGC) of restricticin, a promising antifungal agent featuring a reactive primary amine, from the fungus Aspergillus sclerotiorum LZDX-33-4 by genome mining. Combining heterologous expression and the OSMAC strategy resulted in the production of a new hybrid product (1), along with N-acetyl-restricticin (2) and restricticinol (3). The structure of 1 was determined by spectroscopic data, including optical rotation and electronic circular dichroism (ECD) calculations, for configurational assignment. Compound 1 represents a fusion of restricticin and phytotoxic cichorin. The biosynthetic pathway of 1 was proposed, in which the condensation of a primary amine of restricticin with a precursor of cichorine was postulated. Compound 1 at 5 mM concentration inhibited the growth of the shoots and roots of Lolium perenne, Festuca arundinacea, and Lactuca sativa with inhibitory rates of 71.3 and 88.7% for L. perenne, 79.4 and 73.0% for F. arundinacea, and 58.2 and 52.9% for L. sativa. In addition, compound 1 at 25 µg/mL showed moderate antifungal activity against Fusarium fujikuroi and Trichoderma harzianum with inhibition rates of 22.6 and 31.6%, respectively. These results suggest that heterologous expression in conjunction with the OSMAC approach provides a promising strategy to extend the metabolite novelty due to the incorporation of endogenous metabolites from the host strain with exogenous compounds, leading to the production of more complex compounds and the acquisition of new physiological functions.

Degradation-Risk-Inspired Optimization of the Antifungal Oxazolinyl Aniline Lead by a Fusion of Triazole with Nicotinamide.

The discovery of readily available and easily modifiable new models is a crucial and practical solution for agrochemical innovation. Antifungal function-oriented fusion of triazole with the prevalidated lead (R)-LE001 affords a novel framework with a broad and enhanced antifungal spectrum. Characterized by the easy accessibility and adjustability of [1,2,4]triazolo[4,3-a]pyridine, modular fine-tuning provided a set of unprecedented leads (e.g., Z23, Z25, Z26, etc.) with superior antifungal potentials than the positive control boscalid. Candidate Z23 exhibited a more promising antifungal activity against Sclerotinia sclerotiorum, Botrytis cinerea, and Phytophthora capsici with EC50 values of 0.7, 0.6, and 0.5 µM, respectively. This candidate could effectively control boscalid-resistant B. cinerea strains and also exhibit good vivo efficacy in controlling gray mold. Noteworthily, both the SDH-inhibition and the efficiency against Oomycete P. capsici are quite distinct from that of the positive control boscalid. A molecular docking simulation also differentiates Z23 from boscalid. These findings highlight the potential of [1,2,4]triazolo[4,3-a]pyridine amide as a novel antifungal model.

Discovery, Optimization, and Biological Evaluation of Novel Pyrazol-5-yl-phenoxybenzamide Derivatives as Potent Succinate Dehydrogenase Inhibitors.

The diphenyl ether molecular pharmacophore has played a significant role in the development of fungicidal compounds. In this study, a variety of pyrazol-5-yl-phenoxybenzamide derivatives were synthesized and evaluated for their potential to act as succinate dehydrogenase inhibitors (SDHIs). The bioassay results indicate certain compounds to display a remarkable and broad-spectrum in their antifungal activities. Notably, compound 12x exhibited significant in vitro activities against Valsa mali, Gaeumannomyces graminis, and Botrytis cinerea, with EC50 values of 0.52, 1.46, and 3.42 mg/L, respectively. These values were lower or comparable to those of Fluxapyroxad (EC50 = 12.5, 1.93, and 8.33 mg/L, respectively). Additionally, compound 12x showed promising antifungal activities against Sclerotinia sclerotiorum (EC50 = 0.82 mg/L) and Rhizoctonia solani (EC50 = 1.86 mg/L), albeit lower than Fluxapyroxad (EC50 = 0.23 and 0.62 mg/L). Further in vivo experiments demonstrated compound 12x to possess effective protective antifungal activities against V. mali and S. sclerotiorum at a concentration of 100 mg/L, with inhibition rates of 66.7 and 89.3%, respectively. In comparison, Fluxapyroxad showed inhibition rates of 29.2 and 96.4% against V. mali and S. sclerotiorum, respectively. Molecular docking analysis revealed that compound 12x interacts with SDH through hydrogen bonding, π-cation, and π-π interactions, providing insights into the probable mechanism of action. Furthermore, compound 12x exhibited greater binding energy and SDH enzyme inhibitory activity than Fluxapyroxad (ΔGcal = -46.8 kcal/mol, IC50 = 1.22 mg/L, compared to ΔGcal = -41.1 kcal/mol, IC50 = 8.32 mg/L). Collectively, our results suggest that compound 12x could serve as a promising fungicidal lead compound for the development of more potent SDHIs for crop protection.

Discovery of Novel Acethydrazide-Containing Flavonol Derivatives as Potential Antifungal Agents.

In this study, a series of novel hydrazide-containing flavonol derivatives was designed, synthesized, and evaluated for antifungal activity. In the in vitro antifungal assay, most of the target compounds exhibited potent antifungal activity against seven tested phytopathogenic fungi. In particular, compound C32 showed the best antifungal activity against Rhizoctonia solani (EC50 = 0.170 µg/mL), outperforming carbendazim (EC50 = 0.360 µg/mL) and boscalid (EC50 = 1.36 µg/mL). Compound C24 exhibited excellent antifungal activity against Valsa mali, Botrytis cinerea, and Alternaria alternata with EC50 values of 0.590, 0.870, and 1.71 µg/mL, respectively. The in vivo experiments revealed that compounds C32 and C24 were potential novel agricultural antifungals. 3D quantitative structure-activity relationship (3D-QSAR) models were used to analyze the structure-activity relationships of these compounds. The analysis results indicated that introducing appropriate electronegative groups at position 4 of a benzene ring could effectively improve the anti-R. solani activity. In the antifungal mechanism study, scanning electron microscopy and transmission electron microscopy analyses revealed that C32 disrupted the normal growth of hyphae by affecting the structural integrity of the cell membrane and cellular respiration. Furthermore, compound C32 exhibited potent succinate dehydrogenase (SDH) inhibitory activity (IC50 = 8.42 µM), surpassing that of the SDH fungicide boscalid (IC50 = 15.6 µM). The molecular dynamics simulations and docking experiments suggested that compound C32 can occupy the active site and form strong interactions with the key residues of SDH. Our findings have great potential for aiding future research on plant disease control in agriculture.

Design, Synthesis, and Biological Activity of Silicon-Containing Carboxamide Fungicides.

Bioisosteric silicon replacement has proven to be a valuable strategy in the design of bioactive molecules for crop protection and drug development. Twenty-one novel carboxamides possessing a silicon-containing biphenyl moiety were synthesized and tested for their antifungal activity and succinate dehydrogenase (SDH) enzymatic inhibitory activity. Among these novel succinate dehydrogenase inhibitors (SDHIs), compounds 3a, 3e, 4l, and 4o possessing appropriate clog P and topological polar surface area values showed excellent inhibitory effects against Rhizoctonia solani, Sclerotinia sclerotiorum, Botrytis cinerea, and Fusarium graminearum at 10 mg/L in vitro, and the EC50 values of 4l and 4o were 0.52 and 0.16 mg/L against R. solani and 0.066 and 0.054 mg/L against S. sclerotiorum, respectively, which were superior to those of Boscalid. Moreover, compound 3a demonstrated superior SDH enzymatic inhibitory activity (IC50 = 8.70 mg/L), exhibiting 2.54-fold the potency of Boscalid (IC50 = 22.09 mg/L). Docking results and scanning electron microscope experiments revealed similar mode of action between compound 3a and Boscalid. The new silicon-containing carboxamide 3a is a promising SDHI candidate that deserves further investigation.

Effectiveness of Fludioxonil, a New-Generation Reduced-Risk Fungicide, Against Brown Rot Pathogens.

Brown rot, caused by Monilinia species, is a destructive disease of pome and stone fruits that can lead to significant losses in production. Disease management is mainly based on fungicide applications during the growing season. Fludioxonil, a "new-generation reduced-risk fungicide", is one of the most important fungicide used. The objectives of the present study were to compare and determine the toxicity of fludioxonil to selected M. laxa, M. fructigena and M. fructicola isolates, to test its effectiveness in detached fruits and to assess its effectiveness under practical control conditions. A total of 27 isolates (10 isolates of M. laxa, 8 of M. fructigena and 9 of M. fructicola) were tested for sensitivity to fludioxonil in vitro. Isolates from each species exhibited a homogeneous response to the fungicide, while differences among the different species were determined. Based on calculated resistance factors (RF), the examined isolates were classified into two categories: sensitive and moderately resistant. In vivo testing of the effectiveness of the label concentration of fludioxonil on detached fruit did not reveal differences between isolates classified into different sensitivity categories; fludioxonil used at the label concentration (0.1%) inhibited decay development 93.5 to 100%, regardless of the isolate category. Field trials revealed the very high efficacy of fludioxonil in preventing brown rot on fruits, ranging from 92.2 to 100 for peach, 90.7 to 97.3 for plum and 84.9 to 91.9% for sour cherry. In conclusion, fludioxonil was highly effective according to in vitro sensitivity tests and when used under practical field conditions for brown rot control.

Determination of the amino linkage of the D-Dab residue of the cyclic lipo-octapeptide occidiofungins A-D and the antifungal activity of their analogues.

Recently, the demand for new antifungal drugs has increased due to the presence of antimicrobial resistant bacteria and their side effects. Occidiofungins (Ocfs) are cyclic lipo-octapeptides that possess unusual amino acids and potent antifungal activities. However, the chemical structure of the 2,4-diamino butyric acid (Dab) residue in the backbone of Ocfs has not been clarified thus far. Therefore, we conducted a structural analysis of the tripeptides around the Dab residue in Ocfs using 1H-NMR spectroscopy. We determined that the D-Dab residue in the peptide backbone of Ocfs has an α-amino linkage. Additionally, we found that Ocf A (5) and Bk-1119 have the same chemical structure. Moreover, the analogue possessing D-αDab (13) showed potent antifungal activity against A. oryzae.

Identification of plant based potential antifungal compounds against BMK-1 protein of Bipolaris oryzae using molecular docking approach.

Rice brown spot is an important disease of rice worldwide that inflicts substantial yield losses. The antimicrobial potential of methanol, acetone and dimethyl sulfoxide (DMSO) extracts of different medicinal plants, viz., Syzygium aromaticum, Saussurea costus, Acorus calamus, Bergenia ciliate, Geranium pratense, Mentha longifolia, Inula racemosa, Podophyllum hexandrum, Heracleum candicans and Picrorhiza kurroa, against the brown spot pathogen Bipolaris oryzae in vitro was evaluated via mycelial growth inhibition and spore germination inhibition assays. Among the plant extracts tested, 100% mycelial inhibition was observed for the methanol extract of Syzygium aromaticum at all three concentrations (2000 ppm, 3000 ppm and 4000 ppm), followed by the methanol extract of Inula racemosa (90.33%) at 4000 ppm. A maximum conidial germination inhibition of 83.54% was exhibited by the Heracleum candicans leaf extract. Phytochemical profiling of Syzygium aromaticum and Inula racemosa through liquid chromatography and mass spectrometry (HR-LCMS) revealed the presence of several compounds, such as eugenol, ursolic acid, quercetin, chlorogenic acid, and noscapine. A molecular docking approach was used to identify key inhibitory molecules against B. oryzae. Among the compounds detected in S. aromaticum and Inula racemosa, ursolic acid and noscapine were found to have the greatest binding affinity for the Big Mitogen Activated Protein Kinase (BMK-1) enzyme present in B. oryzae. In conclusion, S. aromaticum and Inula racemosa are potent compounds that could serve as lead compounds for drug discovery in the future.

Deciphering the mechanisms involved in reduced sensitivity to azoles and fengycin lipopeptide in Venturia inaequalis.

Apple scab, caused by the hemibiotrophic fungus Venturia inaequalis, is currently the most common and damaging disease in apple orchards. Two strains of V. inaequalis (S755 and Rs552) with different sensitivities to azole fungicides and the bacterial metabolite fengycin were compared to determine the mechanisms responsible for these differences. Antifungal activity tests showed that Rs552 had reduced sensitivity to tebuconazole and tetraconazole, as well as to fengycin alone or in a binary mixture with other lipopeptides (iturin A, pumilacidin, lichenysin). S755 was highly sensitive to fengycin, whose activity was close to that of tebuconazole. Unlike fengycin, lipopeptides from the iturin family (mycosubtilin, iturin A) had similar activity on both strains, while those from the surfactin family (lichenysin, pumilacidin) were not active, except in binary mixtures with fengycin. The activity of lipopeptides varies according to their family and structure. Analyses to determine the difference in sensitivity to azoles (which target the CYP51 enzyme involved in the ergosterol biosynthesis pathway) showed that the reduced sensitivity in Rs552 is linked to (i) a constitutive increased expression of the Cyp51A gene caused by insertions in the upstream region and (ii) greater efflux by membrane pumps with the involvement of ABC transporters. Microscopic observations revealed that fengycin, known to interact with plasma membranes, induced morphological and cytological changes in cells from both strains. Sterol and phospholipid analyses showed a higher level of ergosta-7,22-dien-3-ol and a lower level of PI(C16:0/C18:1) in Rs552 compared with S755. These differences could therefore influence the composition of the plasma membrane and explain the differential sensitivity of the strains to fengycin. However, the similar antifungal activities of mycosubtilin and iturin A in the two strains indirectly indicate that sterols are probably not involved in the fengycin resistance mechanism. This leads to the conclusion that different mechanisms are responsible for the difference in susceptibility to azoles or fengycin in the strains studied.

Bioactivities evaluation of an endophytic bacterial strain Bacillus tequilensis QNF2 inhibiting apple ring rot caused by Botryosphaeria dothidea on postharvest apple fruits.

Apple ring rot, one of the most common apple postharvest diseases during storage, is caused by Botryosphaeria dothidea. Presently, the disease management is primarily dependent on chemical fungicide application. Here we demonstrated an endophyte bacterium Bacillus tequilensis QNF2, isolated from Chinese leek (Allium tuberosum) roots considerably suppressed B. dothidea mycelial growth, with the highest suppression of 73.56 % and 99.5 % in the PDA and PDB medium, respectively in vitro confront experiments. In in vivo experiments, B. tequilensis QNF2 exhibited a control efficacy of 88.52 % and 100 % on ring rot disease on postharvest apple fruits inoculated with B. dothidea disc and dipped into B. dothidea culture, respectively. In addition, B. tequilensis QNF2 volatile organic compounds (VOCs) also manifested markedly inhibition against B. dothidea mycelial growth and the ring rot on postharvest apple fruits. Moreover, B. tequilensis QNF2 severely damaged the mycelial morphology of B. dothidea. Finally, B. tequilensis QNF2 significantly repressed the expression of six pathogenicity-related genes, such as adh, aldh, aldh3, galm, pdc1, pdc2, involved in glycolysis/gluconeogenesis of B. dothidea. The findings of the study proved that B. tequilensis QNF2 was a promising alternative for controlling apple ring rot of postharvest apple fruit.

Expanding the Structural Diversity of Tubulin-Targeting Agents: Development of Highly Potent Benzimidazoles for Treating Fungal Diseases.

Benzimidazoles, the representative pharmacophore of fungicides, have excellent antifungal potency, but their simple structure and single site of action have hindered their wider application in agriculture. In order to extend the structural diversity of tubulin-targeted benzimidazoles, novel benzimidazole derivatives were prepared by introducing the attractive pyrimidine pharmacophore. 2-((6-(4-(trifluoromethyl)phenoxy)pyrimidin-4-yl)thio)-1H-benzo[d]imidazole (A25) exhibited optimal antifungal activity against Sclerotinia sclerotiorum (S. s.), affording an excellent half-maximal effective concentration (EC50) of 0.158 µg/mL, which was higher than that of the reference agent carbendazim (EC50 = 0.594 µg/mL). Pot experiments revealed that compound A25 (200 µg/mL) had acceptable protective activity (84.7%) and curative activity (78.1%), which were comparable with that of carbendazim (protective activity: 90.8%; curative activity: 69.9%). Molecular docking displayed that multiple hydrogen bonds and π-π interactions could be formed between A25 and ß-tubulin, resulting in a stronger bonding effect than carbendazim. Fluorescence imaging revealed that the structure of intracellular microtubules can be changed significantly after A25 treatment. Overall, these remarkable antifungal profiles of constructed novel benzimidazole derivatives could facilitate the application of novel microtubule-targeting agents.

Risk assessment of resistance to prochloraz in Phoma arachidicola causing peanut web blotch.

Peanut web blotch (PWB) caused by Phoma arachidicola, is one of the most serious foliar diseases of peanut. Although prochloraz is an active fungicide with broad anti-fungal spectrum, it has not been registered for the control of PWB in China. The activity of prochloraz against P. arachidicola and the risk of resistance to prochloraz in P. arachidicola are still unclear. In current study, the inhibitory activity of prochloraz against 96 P. arachidicola strains was determined with the average EC50 value of 1.2700 ± 0.7786 µg/mL. Prochloraz exhibited excellent protective and curative effect on detached peanut leaves, and the effect was obviously better than that of carbendazim and difenoconazole at the same concentration. After prochloraz treatment, the mycelium of P. arachidicola contorted, shrunk and ruptured, with shrinking of cell wall and membrane, enhanced cell membrane permeability, and reduced ergosterol content. Totally 80 prochloraz-resistant mutants were obtained by fungicide adaptation with the frequency of 6.7 × 10-3. All the selected 12 prochloraz-resistant mutants lost their resistance to prochloraz after 10 transfers on PDA plates. And these mutants exhibited decreased biological fitness in mycelial growth and pathogenicity. Moreover, there was positive cross-resistance between prochloraz and other demethylation inhibitor (DMI) fungicides, such as tebuconazole, triflumizole and difenoconazole, but no cross-resistance was found between prochloraz and other classes of fungicides, such as carbendazim, pydiflumetofen or fludioxonil. Overexpression of PaCYP51 and PaAtrB genes were detected in the resistant mutants. All the above results demonstrated that prochloraz has a great potential in management of PWB. The risk of P. arachidicola developing resistance to prochloraz is relatively low-to-medium. Overexpressing of PaCYP51 and PaAtrB might be linked to prochloraz resistance in P. arachidicola.

Design, Synthesis, and Antifungal Activities of Phenylpyrrole Analogues Based on Alkaloid Lycogalic Acid.

Plant diseases caused by pathogenic fungi seriously affect the yield and quality of crops, cause huge economic losses, and pose a considerable threat to global food security. Phenylpyrrole analogues were designed and synthesized based on alkaloid lycogalic acid. All target compounds were characterized by 1H NMR, 13C NMR, and HRMS. Their antifungal activities against seven kinds of phytopathogenic fungi were evaluated. The results revealed that most compounds had broad-spectrum fungicidal activities at 50 µg/mL; 14 compounds displayed more than 60% fungicidal activities against Rhizoctonia cerealis and Sclerotinia sclerotiorum, and in particular, the fungicidal activities of compounds 8g and 8h against Rhizoctonia cerealis were more than 90%, which could be further developed as lead agents for water-soluble fungicides. The molecular docking results indicate that compounds 8g and 8h can interact with 14α-demethylase (RcCYP51) through hydrogen bonding with strong affinity.

Fusarium species,Scedosporium species, and Lomentospora prolificans: A systematic review to inform the World Health Organization priority list of fungal pathogens.

Recognizing the growing global burden of fungal infections, the World Health Organization established a process to develop a priority list of fungal pathogens (FPPL). In this systematic review, we aimed to evaluate the epidemiology and impact of infections caused by Fusarium spp., Scedosporium spp., and Lomentospora prolificans to inform the first FPPL. PubMed and Web of Sciences databases were searched to identify studies published between January 1, 2011 and February 23, 2021, reporting on mortality, complications and sequelae, antifungal susceptibility, preventability, annual incidence, and trends. Overall, 20, 11, and 9 articles were included for Fusarium spp., Scedosporium spp., and L. prolificans, respectively. Mortality rates were high in those with invasive fusariosis, scedosporiosis, and lomentosporiosis (42.9%-66.7%, 42.4%-46.9%, and 50.0%-71.4%, respectively). Antifungal susceptibility data, based on small isolate numbers, showed high minimum inhibitory concentrations (MIC)/minimum effective concentrations for most currently available antifungal agents. The median/mode MIC for itraconazole and isavuconazole were ≥16 mg/l for all three pathogens. Based on limited data, these fungi are emerging. Invasive fusariosis increased from 0.08 cases/100 000 admissions to 0.22 cases/100 000 admissions over the time periods of 2000-2009 and 2010-2015, respectively, and in lung transplant recipients, Scedosporium spp. and L. prolificans were only detected from 2014 onwards. Global surveillance to better delineate antifungal susceptibility, risk factors, sequelae, and outcomes is required.

Pseudomonas protegens volatile organic compounds inhibited brown rot of postharvest peach fruit by repressing the pathogenesis-related genes in Monilinia fructicola.

Brown rot, caused by Monilinia fructicola, is considered one of the devasting diseases of pre-harvest and post-harvest peach fruits, restricting the yield and quality of peach fruits and causing great economic losses to the peach industry every year. Presently, the management of the disease relies heavily on chemical control. In the study, we demonstrated that the volatile organic compounds (VOCs) of endophyte bacterial Pseudomonas protegens QNF1 inhibited the mycelial growth of M. fructicola by 95.35% compared to the control, thereby reducing the brown rot on postharvest fruits by 98.76%. Additionally, QNF1 VOCs severely damaged the mycelia of M. fructicola. RNA-seq analysis revealed that QNF1 VOCs significantly repressed the expressions of most of the genes related to pathogenesis (GO:0009405) and integral component of plasma membrane (GO:0005887), and further analysis revealed that QNF1 VOCs significantly altered the expressions of the genes involved in various metabolism pathways including Amino acid metabolism, Carbohydrate metabolism, and Lipid metabolism. The findings of the study indicated that QNF1 VOCs displayed substantial control efficacy by disrupting the mycelial morphology of M. fructicola, weakening its pathogenesis, and causing its metabolic disorders. The study provided a potential way and theoretical support for the management of the brown rot of peach fruits.

Potassium iodide enhances the killing effect of methylene blue mediated photodynamic therapy against F. monophora.

BACKGROUND: Chromoblastomycosis (CMB) is a chronic granulomatous fungal infection that affect the skin and subcutaneous tissues. It is clinically problematic due to limited treatment options, low cure rates, and high rates of relapse. This underscores the necessity for innovative treatment approaches. In this study, potassium iodide (KI) combined with Methylene Blue (MB) mediated antimicrobial photodynamic therapy (PDT) were assessed in the treatment of Fonsecaea monophora (F. monophora) both in vitro and in vivo. And the underlying mechanism that contributes to the efficacy of this treatment approach was investigated. METHODS: In vitro experiments were conducted using different combinations and concentrations of MB, KI, and 660 nm light (60 mW/cm2) to inhibit F. monophora. The study was carried out using colony-forming unit (CFU) counts and scanning electron microscopy (SEM). The production of singlet oxygen (1O2), free iodine (I2), hydrogen peroxide (H2O2), and superoxide anion during the KI combined MB-mediated antimicrobial PDT process was also detected. In vivo experiments were developed using a Balb/c mouse paw infection model with F. monophora and treated with PBS, 10 mM KI, 2 mM MB +100 J/cm² and 10 mM KI+2 mM MB +100 J/cm² respectively. Inflammatory swelling, fungal load and histopathological analyses of the mouse footpads were assessed. RESULTS: KI enhanced the killing effect of MB-mediated antimicrobial PDT on the conidial spores of F. monophora at the cell and infected animal model level. During the process, the main antimicrobial agents in KI combined with MB- mediated antimicrobial PDT could produce stronger toxic active species including free I2 and H2O2. CONCLUSION: KI combined with MB-mediated antimicrobial PDT could be an effective adjunct therapy for treating CBM.

In vitro evaluation of antifungal combinations against neurotropic dematiaceous fungi associated with primary cerebral phaeohyphomycosis.

Primary cerebral phaeohyphomycosis is a life-threatening disease caused by neurotropic dematiaceous fungi. At present, there are no consensus guidelines regarding optimal antifungal therapy in such cases. Generally, a combination of antifungal agents is recommended for treatment. However, the activities of antifungal combinations against these fungi have not been investigated. In this study, we evaluated the in vitro activities of 13 double and five triple antifungal combinations against clinical isolates of Cladophialophora bantiana (n = 7), Fonsecaea monophora (n = 2), and Cladosporium cladosporioides (n = 1), using a simplified checkerboard procedure. The minimum inhibitory concentrations (MICs) of nine antifungal drugs were determined by the broth microdilution method, and the interaction between antifungal agents in each combination was assessed by the fractional inhibitory concentration index. Excellent activity was observed for posaconazole and itraconazole. Flucytosine had potent activity against C. bantiana but was ineffective against F. monophora, and C. cladosporioides. The echinocandins demonstrated high MICs for all the isolates. Synergistic interactions were observed for all the double combinations, except when itraconazole was combined with either amphotericin B or flucytosine. The combination of amphotericin B with caspofungin showed synergistic interactions against 40% of the isolates. Antagonism was observed with isavuconazole-flucytosine combination against two C. bantiana isolates. The triple combinations of caspofungin and flucytosine with amphotericin B or posaconazole were synergistic against one isolate of F. monophora. For C. cladosporioides, synergy was observed for the triple combination of amphotericin B with caspofungin and flucytosine. Our results indicate that combination of caspofungin with amphotericin B or a triazole, with or without 5-flucytosine has great potential against neurotropic dematiaceous fungi.IMPORTANCEThis research uses a modified version of the checkerboard assay to standardize the in vitro testing of double and triple combinations of antifungal agents against neurotropic dematiaceous fungi. Antifungal combination therapy is associated with improved outcomes in cerebral phaeohyphomycosis. In this study, we demonstrate that posaconazole is the single most active antifungal drug against this group of fungi. The double combination of amphotericin B with caspofungin or a trizole, and the triple combinations of caspofungin and flucytosine with amphotericin B or posaconazole might hold promise in the treatment of cerebral phaeohyphomycosis. Our findings will guide in developing optimal therapeutic strategies for these refractory infections.