Neopestolides A-D, Diphenyl Ether Derivatives from the Plant Endophytic Fungus Neopestalotiopsis sp.

Four new diphenyl ether derivatives, neopestolides A-D ( 2 - 5 ), were isolated from cultures of the plant endophytic fungus Neopestalotiopsis sp., along with the known metabolite pestalotiollide A ( 1 ); their structures were elucidated primarily by NMR experiments. The absolute configurations of 2 and 3 - 5 were deduced by electronic circular dichroism calculations and via Snatzke's method, respectively. Compounds 2 - 4 incorporate tetrahydrofuran moieties attached to the dibenzo[b,g][1,5]dioxocin-5(7 H )-one skeleton via C-C linkages. Compounds 1 and 2 showed modest cytotoxicity against HepG2 cells.