Die antibakterielle Wirkung der Usninsäure auf Mykobakterien und andere Mikroorganismen

Summary Usnic acid has already been found in optically active forms in very different quantities in a large number of species of lichens. We have been able to demonstrate the presence of the racemic form of usnic acid as a naturally occuring product in Iceland moss (Cetraria islandica Ach.). The bacteriological examination of the three forms of usnic acid led to the result that, besides an effect uponStaphylococcus aureus, they exert also a very remarkable action againstMycobacteria. The action ofl-usnic acid on different strains ofMycobacteria and other microorganisms is shown in table II. According to the results so far obtained by us, other acids of lichens behave in a similar manner.