Phylogenetic and chemical diversity of fungal endophytes isolated from Silybum marianum (L) Gaertn. (milk thistle)
Two new naphthopyrones, euplectin (1) and coneuplectin (2), have been isolated from the lichen Flavoparmelia euplecta and their structures elucidated using multidimensional NMR spectroscopic methods, including highfield (600 MHz) gHMBC and gNOE experiments. Cytotoxicity of the more abundant naphthopyrone (1) against the murine P-815 mastocytoma cell line (IC(50) ca. 1.67 microg/mL) has also been evaluated. These compounds are the first lichen metabolites known to contain indenone or indanone moieties in their structure. F. euplecta was also found to contain the known metabolites usnic acid, protocetraric acid, and skyrin.