Laccaridiones A and B, new protease inhibitors from Laccaria amethystea.

In a screening for new inhibitors of proteases as lead structures we disclosed recently the basidiomycete strain of Laccaria amethysteaas the producer of active compounds. Here we report the isolation and structure determination of laccaridiones A (1) and B (2) (Fig. 1) as new inhibitors of trypsin, papain, thermolysin, collagenase and zinc-protease. The strain was isolated from the stem of fruiting body of Laccaria amethystea in the Fagus sylvatica-fovest near Jena (Thuringia, Germany). At the beginning the flat mycelium