New benzophenone derivatives from the coprophilous fungus Delitschia confertaspora

During our ongoing studies of coprophilous (dung-colonizing) fungi as sources of new bioactive secondary metabolites, a culture of the coprophilous fungus Delitschia confertaspora (ATCC 74209) originally obtained from a sample of rock hyrax dung collected in Namibia was targeted for investigation. Previous studies of this culture by scientists at Merck Research Laboratories yielded the unusual 2,6-diketopiperazine derivative flutimide, which inhibits the cap-dependent endonuclease of influenza virus. This fungus has recently been genome-sequenced as part of the 1000 fungal genome project. The interesting chemistry observed in this earlier work, the limited prior studies of other members of the genus, and the lack of reports about other chemistry produced by this species prompted us to undertake further studies of this organism. Chemical investigation of a D. confertaspora fermentation extract resulted in isolation of two new benzophenone derivatives. Both compounds have a somewhat unusual skeleton that incorporates three aromatic rings linked via two ketone carbonyl groups. The structures of these new metabolites were elucidated by analysis of 2D NMR and HRESITOFMS data.