Various natural 8-hydroxyisocoumarin derivatives, i.e., oosponol (1), oospolactone (2), d-phyllodulcin (d-4) and dl-hydrangenol (dl-5), were examined for antifungal activity. Several derivatives of d-4 and dl-5 were also examined. It is very interesting that d-phyllodulcin, a sweetening component of Hydrangea serrata SERINGE var. thunbergii (Japanese name amacha), was found to possess antifungal activity.
