Depsidones and other constituents from Phomopsis sp. CAFT69 and its host plant Endodesmia calophylloides with potent inhibitory effect on motility of zoospores of grapevine pathogen Plasmopara viticola

• Published in: Phytochemistry letters 2012-09, Vol.5 (3), p.657-664
• Main Authors: Talontsi, Ferdinand Mouafo, Islam, Md. Tofazzal, Facey, Petrea, Douanla-Meli, Clovis, von Tiedemann, Andreas, Laatsch, Hartmut
• Format: Article
• Language: English
• Subjects: bioassays; Diaporthe; Downy mildew; Endodesmia calophylloides; Endophytes; Ethers; fungi; Host plants; Motility; N.M.R; natural products; nuclear magnetic resonance spectroscopy; Pathogens; Phomopsis; Phomopsis sp; Plant extracts; Plasmopara viticola; Secondary metabolites; Vitaceae; Vitis; Zoospores; Zoosporicide
• ISSN: 1874-3900; 1876-7486
• DOI: 10.1016/j.phytol.2012.06.017

[Display omitted] ► Zoosporicidal metabolites were isolated from Phomopsis sp. CAFT69 and its host. ► The structures of the new compounds were elucidated by spectroscopic and spectrometric methods. ► The isolates inhibited the motility and viability of the grapevine pathogen Plasmopara viticola zoospores. In our search for secondary metabolites regulating the motility behavior of zoospores of the grapevine downy mildew pathogen Plasmopara viticola, we found that extracts from an endophytic fungus Phomopsis sp. CAFT69 and its host plant Endodesmia calophylloides remarkably impaired motility of zoospores followed by lysis. The active principles in the extracts were isolated and identified as two new compounds, namely excelsional (1a) and 9-hydroxyphomopsidin (2a), together with excelsione (1b), phomopsidin (2b), alternariol (3a), alternariol-5-O-methyl ether (3b), the hitherto undescribed 5′-hydroxyalternariol (3c), altenusin (4) from the fungus, xanthochymol (5) and 1,5-dihydroxy-3-methoxyxanthone (mesuaxanthone, 6) from the plant. Bioassays revealed that compounds 1a/b, 2a/b, and 3a–6 displayed motility inhibition and lytic activities against zoospores of the grapevine downy mildew pathogen P. viticola in a dose- and time-dependent manner from 1 to 10μg/mL. Their structures were elucidated by extensive spectroscopic analyses including 2D NMR techniques. This is the first report of an endophyte and its natural products from E. calophylloides and the first isolation of compounds 5 and 6 from this plant.