Heptemerones A∼G, Seven Novel Diterpenoids from Coprinus heptemerus: Producing Organism, Fermentation, Isolation and Biological Activities

Seven novel diterpenoids, named heptemerones A∼G, were isolated from the broth of submerged cultures of Coprinus heptemerus, a basidiomycete which previously had not been known to produce secondary metabolites. The compounds were purified by solid phase extraction and silica gel chromatography followed by preparative HPLC. Among the biological activities the inhibition of fungal germination was the most potent, and depended highly on the composition of the assay medium. In water, inhibition occurred at 5∼10 fold lower concentrations as compared to complex media. Heptemerone G was the most active compound with MICs starting at 1 µg/ml. Four of the antifungal compounds exhibited plant protective activity in a leaf segment assay using Magnaporthe grisea as the pathogen. Growth of yeasts and bacteria was hardly affected. Cytotoxic activities were moderate and only heptemerone D was phytotoxic.