New diplosporin and agistatine derivatives produced by the fungal endophyte Xylaria sp. isolated from Vitis labrusca

A Xylaria sp. was isolated as an endophyte from a surface-sterilized Concord grape leaf (Vitis labrusca). Dereplication and LC–MS analysis of the filtrate extracts identified two new structures, compound 1, 13-O-methyl-(5R) diplosporin, and 2 a new agistatine. Additionally, five known compounds 3–7 including an agistatine, coriloxin, (5R)-diplosporin, and two mellein derivatives were also isolated. This is the first report of these structurally-related metabolites isolated from the same fungus, suggesting they share a related biosynthesis. Metabolites were isolated using liquid chromatography-solid phase extraction (LC-SPE) and semi-preparative HPLC. Structures were elucidated on the basis of 1D and 2D NMR analysis, HRMS measurements and X-ray structural analysis for compound 1.