RESUMO
Chemical investigation of the endophyte Pseudofusicoccum stromaticum CMRP4328 isolated from the medicinal plant Stryphnodendron adstringens yielded ten compounds, including two new dihydrochromones, paecilins Q (1: ) and R (2: ). The antifungal activity of the isolated metabolites was assessed against an important citrus pathogen, Phyllosticta citricarpa. Cytochalasin H (6: ) (78.3%), phomoxanthone A (3: ) (70.2%), phomoxanthone B (4: ) (63.1%), and paecilin Q (1: ) (50.5%) decreased in vitro the number of pycnidia produced by P. citricarpa, which are responsible for the disease dissemination in orchards. In addition, compounds 3: and 6: inhibited the development of citrus black spot symptoms in citrus fruits. Cytochalasin H (6: ) and one of the new compounds, paecilin Q (1: ), appear particularly promising, as they showed strong activity against this citrus pathogen, and low or no cytotoxic activity. The strain CMRP4328 of P. stromaticum and its metabolites deserve further investigation for the control of citrus black spot disease.
Assuntos
Antifúngicos , Citrus , Antifúngicos/farmacologia , Doenças das Plantas/prevenção & controle , Doenças das Plantas/microbiologia , EndófitosRESUMO
Citrus black spot (CBS) and post-bloom fruit drop (PFD), caused by Phyllosticta citricarpa and Colletotrichum abscissum, respectively, are two important citrus diseases worldwide. CBS depreciates the market value and prevents exportation of citrus fruits to Europe. PFD under favorable climatic conditions can cause the abscission of flowers, thereby reducing citrus production by 80%. An ecofriendly alternative to control plant diseases is the use of endophytic microorganisms, or secondary metabolites produced by them. Strain LGMF1631, close related to Diaporthe cf. heveae 1, was isolated from the medicinal plant Stryphnodendron adstringens and showed significant antimicrobial activity, in a previous study. In view of the potential presented by strain LGMF1631, and the absence of chemical data for secondary metabolites produced by D. cf. heveae, we decided to characterize the compounds produced by strain LGMF1631. Based on ITS, TEF1, and TUB phylogenetic analysis, strain LGMF1631 was confirmed to belong to D. cf. heveae 1. Chemical assessment of the fungal strain LGMF1631 revealed one new seco-dihydroisocoumarin [cladosporin B (1)] along with six other related, already known dihydroisocoumarin derivatives and one monoterpene [(-)-(1S,2R,3S,4R)-p-menthane-1,2,3-triol (8)]. Among the isolated metabolites, compound 5 drastically reduced the growth of both phytopathogens in vitro and completely inhibited the development of CBS and PFD in citrus fruits and flowers. In addition, compound 5 did not show toxicity against human cancer cell lines or citrus leaves, at concentrations higher than used for the inhibition of the phytopathogens, suggesting the potential use of (-)-(3R,4R)-cis-4-hydroxy-5-methylmellein (5) to control citrus diseases.
Assuntos
Ascomicetos/efeitos dos fármacos , Citrus/microbiologia , Fungicidas Industriais/farmacologia , Isocumarinas/farmacologia , Saccharomycetales/química , Ascomicetos/fisiologia , Colletotrichum/efeitos dos fármacos , Colletotrichum/fisiologia , Fabaceae/microbiologia , Frutas/microbiologia , Fungicidas Industriais/química , Fungicidas Industriais/metabolismo , Isocumarinas/química , Isocumarinas/metabolismo , Filogenia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Saccharomycetales/classificação , Saccharomycetales/genética , Saccharomycetales/isolamento & purificaçãoRESUMO
Endophytic fungi have been considered a rich source for bioactive secondary metabolites with novel chemical structures. A high diverse group of endophytes, isolated from different medicinal plants, belongs to the genus Diaporthe. In a previously study performed by our group the crude extract of strain LGMF1583 showed considerable antibacterial activity mainly against Gram-negative bacteria. Based on ITS phylogeny analysis, strain LGMF1583 was identified as belonging to Diaporthe genus and may represent a new species. In the present study, we described the new species Diporthe vochysiae based on multilocus phylogeny analysis and morphological characteristics. The species name refers to the host, from which strain LGMF1583 was isolated, the medicinal plant Vochysia divergens. In view of the biotechnological potential of strain LGMF1583, we have also characterized the secondary metabolites produced by D. vochysiae. Chemical assessment of the D. vochysiae LGMF1583 revealed two new carboxamides, vochysiamides A (1) and B (2), in addition to the known metabolite, 2,5-dihydroxybenzyl alcohol (3). In the biological activity analysis, vochysiamide B (2) displayed considerable antibacterial activity against the Gram-negative bacterium Klebsiella pneumoniae (KPC), a producer of carbapenemases, MIC of 80⯵g/mL. Carbapenemases are considered a major antimicrobial resistance threat, and infections caused by KPC have been considered a public health problem worldwide, and new compounds with activity against this bacterium are nowadays even more required.
Assuntos
Amidas/farmacologia , Antibacterianos/farmacologia , Ascomicetos/química , Myrtales/microbiologia , Plantas Medicinais/microbiologia , Amidas/isolamento & purificação , Antibacterianos/isolamento & purificação , Ascomicetos/classificação , Brasil , Linhagem Celular Tumoral , Endófitos/química , Humanos , Klebsiella pneumoniae/efeitos dos fármacos , Estrutura Molecular , FilogeniaRESUMO
The isolation and structure elucidation of one new fungal metabolite, phenguignardic acid butyl ester (1a), and four previously reported metabolites (1b, 2a, 3-4) from the citrus phytopathogen Phyllosticta citricarpa LGMF06 are described. The new dioxolanone phenguignardic acid butyl ester (1a) had low phytotoxic activity in citrus leaves and fruits (at dose of 100 µg), and its importance as virulence factor in citrus black spot disease needs to be further addressed. Beside the phytotoxic analysis, we also evaluated the antibacterial (against methicillin sensitive and resistant Staphylococcus aureus) and cytotoxic (A549 non-small cell lung cancer, PC3 prostate cancer and HEL 299 normal epithelial lung) activities of the isolated compounds, which revealed that compounds 1a, 1b and 2a were responsible for the antibacterial activity of this strain.
Assuntos
Antibacterianos/isolamento & purificação , Antibacterianos/farmacologia , Ascomicetos/química , Produtos Biológicos/isolamento & purificação , Produtos Biológicos/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Antibacterianos/química , Antineoplásicos/química , Antineoplásicos/isolamento & purificação , Antineoplásicos/farmacologia , Produtos Biológicos/química , Produtos Biológicos/toxicidade , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Citrus/microbiologia , Humanos , Estrutura Molecular , Doenças das Plantas/microbiologiaRESUMO
Microorganisms associated with plants are highly diverse and can produce a large number of secondary metabolites, with antimicrobial, anti-parasitic and cytotoxic activities. We are particularly interested in exploring endophytes from medicinal plants found in the Pantanal, a unique and widely unexplored wetland in Brazil. In a bio-prospecting study, strains LGMF1213 and LGMF1215 were isolated as endophytes from Vochysia divergens, and by morphological and molecular phylogenetic analyses were characterized as Phaeophleospora vochysiae sp. nov. The chemical assessment of this species reveals three major compounds with high biological activity, cercoscosporin (1), isocercosporin (2) and the new compound 3-(sec-butyl)-6-ethyl-4,5-dihydroxy-2-methoxy-6-methylcyclohex-2-enone (3). Besides the isolation of P. vochysiae as endophyte, the production of cercosporin compounds suggest that under specific conditions this species causes leaf spots, and may turn into a pathogen, since leaf spots are commonly caused by species of Cercospora that produce related compounds. In addition, the new compound 3-(sec-butyl)-6-ethyl-4,5-dihydroxy-2-methoxy-6-methylcyclohex-2-enone showed considerable antimicrobial activity and low cytotoxicity, which needs further exploration.
Assuntos
Bactérias/isolamento & purificação , Myrtales/metabolismo , Myrtales/microbiologia , Antibacterianos/metabolismo , Anti-Infecciosos/metabolismo , Ascomicetos/metabolismo , Bactérias/metabolismo , Brasil , Endófitos/metabolismo , Magnoliopsida/metabolismo , Magnoliopsida/microbiologia , Testes de Sensibilidade Microbiana , Perileno/análogos & derivados , Filogenia , Plantas Medicinais/metabolismoRESUMO
Amphibian vertebrates are important models in regenerative biology because they present exceptional regenerative capabilities throughout life. However, it takes considerable effort to rear amphibians to juvenile and adult stages for regeneration studies, and the relatively large sizes that frogs and salamanders achieve during development make them difficult to use in chemical screens. Here, we introduce a new tail regeneration model using late stage Mexican axolotl embryos. We show that axolotl embryos completely regenerate amputated tails in 7days before they exhaust their yolk supply and begin to feed. Further, we show that axolotl embryos can be efficiently reared in microtiter plates to achieve moderate throughput screening of soluble chemicals to investigate toxicity and identify molecules that alter regenerative outcome. As proof of principle, we identified integration 1 / wingless (Wnt), transforming growth factor beta (Tgf-ß), and fibroblast growth factor (Fgf) pathway antagonists that completely block tail regeneration and additional chemicals that significantly affected tail outgrowth. Furthermore, we used microarray analysis to show that inhibition of Wnt signaling broadly affects transcription of genes associated with Wnt, Fgf, Tgf-ß, epidermal growth factor (Egf), Notch, nerve growth factor (Ngf), homeotic gene (Hox), rat sarcoma/mitogen-activated protein kinase (Ras/Mapk), myelocytomatosis viral oncogene (Myc), tumor protein 53 (p53), and retinoic acid (RA) pathways. Punctuated changes in the expression of genes known to regulate vertebrate development were observed; this suggests the tail regeneration transcriptional program is hierarchically structured and temporally ordered. Our study establishes the axolotl as a chemical screening model to investigate signaling pathways associated with tissue regeneration.
Assuntos
Ambystoma mexicanum/genética , Regeneração/genética , Transdução de Sinais/genética , Animais , Análise em Microsséries/métodos , Transcrição Gênica/genética , Vertebrados/genéticaRESUMO
Endophytic actinomycetes encompass bacterial groups that are well known for the production of a diverse range of secondary metabolites. Vochysia divergens is a medicinal plant, common in the "Pantanal" region (Brazil) and was focus of many investigations, but never regarding its community of endophytic symbionts. During a screening program, an endophytic strain isolated from the V. divergens, was investigated for its potential to show biological activity. The strain was characterized as Microbispora sp. LGMB259 by spore morphology and molecular analyze using nucleotide sequence of the 16S rRNA gene. Strain LGMB259 was cultivated in R5A medium producing metabolites with significant antibacterial activity. The strain produced 4 chemically related ß-carbolines, and 3 Indoles. Compound 1-vinyl-ß-carboline-3-carboxylic acid displayed potent activity against the Gram-positive bacterial strains Micrococcus luteus NRRL B-2618 and Kocuria rosea B-1106, and was highly active against two human cancer cell lines, namely the prostate cancer cell line PC3 and the non-small-cell lung carcinoma cell line A549, with IC50 values of 9.45 and 24.67 µM, respectively. 1-Vinyl-ß-carboline-3-carboxylic acid also showed moderate activity against the yeast Saccharomyces cerevisiae ATCC204508, as well as the phytopathogenic fungi Phyllosticta citricarpa LGMB06 and Colletotrichum gloeosporioides FDC83.