Trienylfuranol A and trienylfuranone A–B: metabolites isolated from an endophytic fungus, Hypoxylon submoniticulosum, in the raspberry Rubus idaeus

A strain of Hypoxylon submonticulosum was isolated as an endophyte from a surface-sterilized leaf of a cultivated raspberry ( Rubus idaeus ). The liquid culture extract displayed growth inhibition activity against Saccharomyces cerevisiae using a disc diffusion assay. The extract’s major component was identified as a new natural product, trienylfuranol A (1 S ,2 S ,4 R )-1-((1′ E ,3′ E )-hexa-1′,3′,5′-trienyl)-tetrahydro-4-methylfuran-2-ol ( 1 ), by high-resolution LC-MS and 1D and 2D NMR spectroscopy. Two additional new metabolites, trienylfuranones A ( 2 ) and B ( 3 ), were isolated as minor components of the extract and their structure elucidation revealed that they were biosynthetically related to 1 . Absolute stereochemical configurations of compounds 1 – 3 were confirmed by NOE NMR experiments and by the preparation of Mosher esters. Complete hydrogenation of 1 yielded tetrahydrofuran 7 that was used for stereochemical characterization and assessment of antifungal activity.