Dihydroisocoumarins from fungi: isolation, structure elucidation, circular dichroism and biological activity.

Five known and three new dihydroisocoumarins were isolated from different fungi. The new isocoumarins are 5-chloro-6-hydroxymellein, 5-chloro-4,6-dihydroxymellein and 5,6-dihydroxymellein. The absolute configuration of these secondary metabolites was confirmed by CD measurements and in two cases by X-ray structure analysis.