Antifungal activities of cytochalasins produced by Diaporthe miriciae, an endophytic fungus associated with tropical medicinal plants

Authors: CARVALHO, CAMILA - Federal University Of Minas Gerais; D'SILVA, ALICE - Federal University Of Minas Gerais; Wedge, David; Cantrell, Charles; ROSA, LUIZ - Federal University Of Minas Gerais

Submitted to: Canadian Journal of Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/25/2018
Publication Date: 6/20/2018
Citation: Carvalho, C.R., D'Silva, A.F., Wedge, D.E., Cantrell, C.L., Rosa, L.H. 2018. Antifungal activities of cytochalasins produced by Diaporthe miriciae, an endophytic fungus associated with tropical medicinal plants. Canadian Journal of Microbiology. 64:835-843. https://doi.org/10.1139/cjm-2018-0131.
DOI: https://doi.org/10.1139/cjm-2018-0131

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: In the present study, we evaluated the antifungal potential of cytochalasins produced by Diaporthe taxa against phytopathogenic fungi. Using molecular methods, seven endophytic fungal strains from the medicinal plants Copaifera pubiflora and Melocactus ernestii were identified as Diaporthe miriciae, while two isolates were identified to the genus level (Diaporthe sp.). All crude extracts of Diaporthe species produced via solid-state fermentation were evaluated by 1H NMR analyses. Crude extracts of the isolates D. miriciae UFMGCB 6350, 7719, 7646, 7653, 7701, 7772, and 7770 and Diaporthe sp. UFMGCB 7696 and 7720 were demonstrated to produce highly functionalized compounds. The extracts of D. miriciae UFMGCB 7719 and 6350 were selected as representative Diaporthe samples and subjected to bioassay-directed fractionation to isolate cytochalasins H and J. Cytochalasins H and J were evaluated for activities against the fungal plant pathogens Colletotrichum fragariae, Colletotrichum gloeosporioides, Colletotrichum acutatum, Botrytis cinerea, Fusarium oxysporum, Phomopsis obscurans, and Phomopsis viticola using microdilution broth assays. Cytochalasins H and J exhibited the most potent activities against the Phomopsis species tested. Our results showed that Diaporthe species were potential producers of different cytochalasins, which exhibit potential for controlling fungal diseases in planta and (or) maintaining antagonism.