The Secondary Metabolites From An Endolichenic Fungus Sporormiella Minima (No.66-3-4-2)

Contents: The EtOAc extract of an endolichenic fungus (Sporormiella minima,No.66-3-4-2) was under chemical investigation to searching for secondarymetabolites with novel structure or bioactivity. Methods: Compounds were obtainedby the combined utilization of silica gel column chromagraphy, ODS chromagraphy,semi-preparative HPLC and preparative HPLC. And the isolated compounds wereidentified by UV, IR, MS, CD,1D and2D NMR, X-ray, and chemical reaction.Results and Dissusions: Eighteen compounds, including fourteen xanthone-relatedderivatives, two diphenyl ethers and two benzoic acid derivatives, have been isolatedfrom the rice culture media of the strain Sporormiella minima (No.66-3-4-2). Five ofthem are new compounds, named sporormiellins A-C (1-3), sporormiellone A (4), and(4R,5R)-methyl4-acetoxy-5,7-dihydroxy-3-methyl-6-oxo-5,6-dihydro-4H-oxepino[2,3-b]chromene-5-carboxylate (8) respectively. Among them compound1features an unprecedentedtetracyclic skeleton core (6/6/5/5), which is the first case of tetrahydrofuran-fusedfurochromones. According to the isolated xanthone derivatives, a hypotheticalbiogenetic pathway for these xanthones is proposed. This chemical investigation of S.minima improves the level of understanding secondary metabolites from Sporormiellafungi, and the discovery of the first case of tetrahydrofuran-fused furochromonesenriches the structural diversity of natural products, which are innovative.