Tricycloalternarene derivatives from the endophytic fungus Guignardia bidwellii PSU-G11

► Four new tricycloalternarenes, guignarenones A-D, from Guignardia bidwellii PSU-G11. ► The absolute configurations were assigned using Mosher's method and NOEDIFF data. ► Guignarenone A displayed cytotoxic activity.