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Research Project: Health-Promoting Bioactives and Biobased Pesticides from Medicinal and Herbal Crops

Location: Natural Products Utilization Research

Title: Antifungal cytochalasins produced by diaporthe miriciae: an endophytic fungus associated with medicinal tropical plants

Author
item Carvalho, Camila - Federal University Of Minas Gerais
item D'silva, Alice - Federal University Of Minas Gerais
item Wedge, David
item Cantrell, Charles
item Rosa, Luiz - Federal University Of Minas Gerais

Submitted to: Open Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/26/2018
Publication Date: 6/20/2018
Citation: Carvalho, C.R., D'Silva, A.F., Wedge, D.E., Cantrell, C.L., Rosa, L.H. 2018. Antifungal cytochalasins produced by diaporthe miriciae: an endophytic fungus associated with medicinal tropical plants. Open Chemistry. 16:306-316. https://doi.org/10.1515/chem.2018-0028.
DOI: https://doi.org/10.1515/chem.2018-0028

Interpretive Summary: The antifungal potential of cytochalasins produced by fungi in the Diaporthe taxa was examined against phytopathogenic fungi. Nine endophytic fungi obtained from medicinal plants Copaifera pubiflora (Fabaceae) and Melocactus ernestii (Cactaceae). The endophytic fungal isolates were identified as Diaporthe species by molecular methods. Extracts of D. miriciae UFMGCB 7719 and 6350 were selected as representative of the group and subsequently subjected to bioassay-directed fractionation resulting in the isolation of the cytochalasin H and J. These cytochalasins were evaluated for their antifungal activity against the fungal plant pathogens Colletotrichum fragariae, C. gloeosporioides, C. acutatum, Botrytis cinerea, Fusarium oxysporum, Phomopsis obscurans, and P. viticola in microdilution broth assays. Cytochalasin H and J displayed the most activity against Phomopsis species with 36-73% growth inhibition observed at 300 µM. Our results showed that the cytochalasins may inhibit or control fungal diseases in the plant.

Technical Abstract: The antifungal potential of cytochalasins produced by Diaporthe taxa was examined against phytopathogenic fungi. Nine endophytic fungi obtained from the Culture Collection of Microorganisms and Cells of the Federal University of Minas Gerais, Brazil were originally isolated from medicinal plants Copaifera pubiflora (Fabaceae) and Melocactus ernestii (Cactaceae). The endophytic fungal isolates were identified as Diaporthe species by molecular methods through amplifications of the internal transcribed region of the nuclear ribosomal RNA gene and ß-tubulin gene. Seven species were identified as D. miriciae, while two isolates remained at the genera level. All crude extracts of Diaporthe species were evaluated by 1H NMR analyses. Crude extracts of D. miriciae UFMGCB 6350, 7719, 7646, 7653, 7701, 7772, 7770 and Diaporthe sp. UFMGCB 7696 and 7720 showed the presence of the highly functionalized compounds. The extracts of D. miriciae UFMGCB 7719 and 6350 were selected as representative of the group and subsequently subjected to bioassay-directed fractionation resulting in the isolation of the cytochalasin H and J. These cytochalasins were evaluated for their activity against the fungal plant pathogens Colletotrichum fragariae, C. gloeosporioides, C. acutatum, Botrytis cinerea, Fusarium oxysporum, Phomopsis obscurans, and P. viticola in microdilution broth assays. Cytochalasin H and J displayed the most activity against Phomopsis species with 36-73% growth inhibition observed at 300 µM after 144 h. Our results showed that the Diaporthe species were prolific producers of different cytochalasins, suggesting that these compounds may inhibit or control fungal diseases in planta and/or help to maintain a balance of antagonism.