Antimicrobial metabolites produced by endophytic fungi associated with the leaves of Vochysia divergens.

Investigation of the endophytic fungi Nigrospora sphaerica, Nigrospora oryzae, and Pseudofusicoccum stromaticum MeOH fractions isolated from the leaves of Vochysia divergens, a medicinal species from the Brazilian Pantanal, led to the identification of five compounds, namely a new compound (1E,8Z)-10,11-dihydroxy-5,5,8-trimethyl-4-oxocycloundeca-1,8-diene-1-carbaldehyde (1) and four known compounds: 5-methylmellein (2), sclerone (3), daldinone A (4), and lasiodiplodin (5). All compounds were identified using spectroscopic methods, and 1 was corroborated with mass spectrometry, while the known compounds were compared with data in the literature. The relative configuration of compound 1 was determined based on theoretical conformational studies as well as the J experimental values between the hydroxymethyne hydrogens. The antimicrobial activity of the compounds was evaluated. Promising results were obtained for compounds 2, 4, and 5 since they inhibited the bacterium Pseudomonas aeruginosa, an opportunistic pathogen, suggesting the potential of these microorganisms as a source of new antibacterial agents.

Characterization of Peptaibols Produced by a Marine Strain of the Fungus Trichoderma endophyticum via Mass Spectrometry, Genome Mining and Phylogeny-Based Prediction.

Trichoderma is recognized as a prolific producer of nonribosomal peptides (NRPs) known as peptaibols, which have remarkable biological properties, such as antimicrobial and anticancer activities, as well as the ability to promote systemic resistance in plants against pathogens. In this study, the sequencing of 11-, 14- and 15-res peptaibols produced by a marine strain of Trichoderma isolated from the ascidian Botrylloides giganteus was performed via liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-MS/MS). Identification, based on multilocus phylogeny, revealed that our isolate belongs to the species T. endophyticum, which has never been reported in marine environments. Through genome sequencing and genome mining, 53 biosynthetic gene clusters (BGCs) were identified as being related to bioactive natural products, including two NRP-synthetases: one responsible for the biosynthesis of 11- and 14-res peptaibols, and another for the biosynthesis of 15-res. Substrate prediction, based on phylogeny of the adenylation domains in combination with molecular networking, permitted extensive annotation of the mass spectra related to two new series of 15-res peptaibols, which are referred to herein as "endophytins". The analyses of synteny revealed that the origin of the 15-module peptaibol synthetase is related to 18, 19 and 20-module peptaibol synthetases, and suggests that the loss of modules may be a mechanism used by Trichoderma species for peptaibol diversification. This study demonstrates the importance of combining genome mining techniques, mass spectrometry analysis and molecular networks for the discovery of new natural products.

Metabolomic Analysis of Combretum lanceolatum Plants Interaction with Diaporthe phaseolorum and Trichoderma spirale Endophytic Fungi through 1 H-NMR.

Endophytic fungi are an important class of microorganisms, able to interact with a host plant via a mutualistic mechanism without visible symptoms of the fungal colonization. The synergy between endophytic fungi and their host plant can promote morphological, physiological and biochemical changes through the expression of bioactive metabolites. This work aims to correlate metabolic changes in the Combretum lanceolatum plant metabolome with its endophytic fungi Diaporthe phaseolorum (Dp) and Trichoderma spirale (Ts), and to discover corresponding metabolite-biomarkers, with the principal focus being on its primary metabolism. The 1 H-NMR metabolomic analysis of qualitative and quantitative changes was performed through multivariate statistical analysis and the identification of primary metabolites was achieved on the Madison Metabolomics Consortium Database. The presence of Dp significantly impacted the plant's metabolic pathways, improving the biosynthesis of primary metabolites such as threonine, malic acid and N-acetyl-mannosamine, which are precursors of special metabolites involved in plant self-defence. This work represents a valuable contribution to advanced studies on the metabolic profiles of the interaction of plants with endophytes.

Evaluation of antileishmanial activity of harzialactone a isolated from the marine-derived fungus Paecilomyces sp.

Fractionation of extracts from the culture broth of the marine-derived fungus, Paecilomyces sp. 7A22, resulted in the isolation of the harzialactone A (HA), a known compound previously isolated from fungi of marine environments. The chemical structure of HA was determined by spectroscopic analyses. Upon evaluation of HA on antileishmanial assays against Leishmania amazonensis, HA exhibited significant activity against promastigotes forms with IC50 of 5.25 µg mL-1 and moderate activity against intracellular amastigotes with IC50 of 18.18 µg mL-1. This is the first report on the antileishmanial activity of HA, and the effects of HA presented in this work suggest that this class of compounds are suitable for future biological in vitro and in vivo studies for the search of natural products with activity against Leishmania spp. Furthermore, the present results corroborate marine-derived fungi as a promising source of natural products with antiparasitic activity.

Larvicidal activity of substituted chalcones against Aedes aegypti (Diptera: Culicidae) and non-target organisms.

BACKGROUND: The expansion of Aedes aegypti (Diptera: Culicidae) population has increased the number of cases of arboviruses, in part due to the inefficiency and toxicity of the chemical control methods available to control this vector. We synthesized 19 chalcone derivatives and examined their activity against Ae. aegypti larvae in order to select larvicidal compounds that are non-toxic to other organisms. RESULTS: Seven chalcone derivatives (3a, 3e, 3f, 6a, 6c, 6d, and 6f) had lethal concentrations of substituted chalcones capable of killing 50% (LC50 ) values lower than 100 mg mL-1 at 24 h post-treatment, which is the dose that the World Health Organization recommends for the selection of promising larvicides. The type of substituent added to (E)-1,3-diphenylprop-2-en-1-one (3a) markedly affected the larvicidal activity. Addition of chlorine, bromine and methoxy groups to the aromatic rings reduced the larvicidal activity, while replacement of the B-ring (phenyl) by a furan ring significantly increased the larvicidal activity. The furan-chalcone (E)-3-(4-bromophenyl)-1-(furan-2-yl)prop-2-en-1-one (6c) killed Ae. aegypti larvae (LC50 = 6.66 mg mL-1 ; LC90 = 9.97 mg mL-1 ) more effectively than the non-substituted chalcone (3a) (LC50 = 14.43 mg mL-1 ; LC90 = 20.96 mg mL-1 ), and was not toxic to the insect Galleria mellonella, to the protozoan Tetrahymena pyriformis, and to the algae Chorella vulgaris. CONCLUSIONS: The substitution pattern of chalcones influenced their larvicidal activity. In the set of compounds tested, (E)-3-(4-bromophenyl)-1-(furan-2-yl)prop-2-en-1-one (6c) was the most effective larvicide against Ae. aegypti, with no clear signs of toxicity to other animal models. Its mechanism of action and effectiveness under field conditions remain to be determined.

Endophytic fungal extracts: evaluation as photosynthesis and weed growth inhibitors.

A central pillar of modern weed control is the discovery of new herbicides which are nontoxic to humans and the environment and which have low application dosage. The natural products found in plants and microorganisms are well suited in this context because they are generally nontoxic and have a wide variety of biological activities. In this work, Diaporthe phaseolorum (Dp), Penicillium simplicissimum (Ps) and Trichoderma spirale (Ts) (methanolic extracts) were evaluated as photosynthesis and plant growth inhibitors in Senna occidentalis and Ipomoea grandifolia. The most significant results were observed for Ts and Dp in S. occidentalis and I. grandifolia, respectively. Ts reduced PI(abs), ET0/CS0, PHI(E0) and PSI0 parameters by 64, 28, 40 and 38%, respectively, indicating a reduction on electron transport efficiency. Additionally, Ts decreased shoot length by 9%, affecting the plant growth. Dp reduced PI(abs), ET0/CS0 and PHI(E0) parameters by 50, 20, 26 and 22%, respectively, revealing the inhibition competency on PSII acceptor site. Furthermore, Dp decreased by 50% the shoot length on germination assay. Thus, the phytotoxic behaviors based on endophytic fungal extracts may serve as a valuable tool in the further development of a bioherbicide since natural products represent an interesting alternative to replace commercial herbicides.

Bacterial communities of three plant species from Pb-Zn contaminated sites and plant-growth promotional benefits of endophytic Microbacterium sp. (strain BXGe71).

The endophytic bacterial community of two hyperaccumulators (Arabis alpine, Dysphania ambrosioides) and Veronica ciliate was investigated by Illumina sequencing technology. In addition, the culturable endophytic bacteria (EB) were isolated and their plant-growth promotion capabilities were studied. A dataset consisting of 221,075 filtered high-quality and classifiable unique 16S rDNA gene tags, and an average of 36,846 tags with a mean length of 464-bp for each sample was generated. In total, 10801 different operational taxonomic units (OTUs) were detected, belonging to 18 bacterial phyla, 41 classes, 91 orders, 135 families, and 215 genera. Pseudomonas was the most dominant genus in both shoots and roots of the two hyperaccumulators, making up 81.56% and 81.13%, 41.60% and 77.06% of the total number of OTUs, respectively. However, both Chao 1 and Shannon indices of EB of the two hyperaccumulators were significantly lower than those of V. ciliate (P <. 05), except the Shannon index of D. ambrosioides shoots. The endophytic bacterial community of roots and shoots of A. alpine showed greater similarity with that of D. ambrosioides roots (12 km away), and clustered to one group in dendrogram, in clear contrast to that of V. ciliate, which grew closer to A. alpine (60 m away). Combining results of soil and plant analyses, we suggest that the soil properties, especially heavy metal concentration, may influence the plants endophytic bacterial community composition. Pot experiments showed that the strain BXGe71 (Microbacterium sp.) from A. alpine significantly enhanced host plants' growth under multi-heavy metal (HM) stress (P < .05, t-test).

Aromatic compounds produced by endophytic fungi isolated from red alga Asparagopsis taxiformis - Falkenbergia stage.

Endophytic fungi were isolated from red alga Asparagopsis taxiformis - Falkenbergia stage, collected from the Brazilian coast, and were identified as Annulohypoxylon stygium (AT-03) and A. yungensis (AT-06) based on their macro/micromorphological and molecular features. Bioassay-guided fractionation of the EtOAc extract from laboratory cultures of both strains yielded known compounds pyrogallol from A. stygium, (3 R)-scytalone and (3 R,4 R)-4-hydroxy-scytalone from A. yungensis. Pyrogallol was active against methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli strains. An inactive fraction from A. stygium afforded two additional compounds, (3 R,4 R)-3,4,5-trihydroxy-1-tetralone and tyrosol. Optically active compounds had their stereochemistry determined by circular dichroism (CD) spectroscopy.

Screening of inducers for laccase production by Lentinula edodes in liquid medium

Lacases são enzimas envolvidas na degradação da lignina e produzidas por diversos organismos. Devido à sua baixa especificidade por substratos, seu potencial para utilização em aplicações biotecnológicas tem sido objeto de investigação. A adição de indutores de lacases ao meio de cultivo de microrganismos aumenta a produção dessas enzimas, facilitando sua purificação e utilização. Este trabalho teve como objetivo investigar o efeito de alguns compostos utilizados como indutores de lacases em fungos na produção destas enzimas por Lentinula edodes (shiitake). Previamente a utilização de indutores, foi selecionado um meio de cultura para a produção de lacases por shiitake, utilizando-se duas concentrações de N (2,6 mM e 26 mM) e sete de Cu (0, 50, 100, 150, 200, 250 e 300 µM). O meio no qual maior atividade de lacases foi detectada continha 2,6 mM N e 250 µM de Cu. Posteriormente, ao meio selecionado foram adicionados ácido gálico (1 mM), catecol (1 mM), tartarato de amônio (55 µM), ácido hidroxibenzóico (1 mM) e vanilina (1 mM). Os dois primeiros compostos inibiram completamente a atividade de lacases por shiitake, e um experimento com os restantes foi conduzido por 30 dias. Apenas as culturas com tartarato de amônio apresentaram atividade de lacase maior que o tratamento controle, alcançando 251 U/mL de extrato após 30 dias de cultivo. Um gel de atividade (native PAGE) exibiu apenas uma banda, sugerindo não haver produção e isozimas.