A member of the class of dibenzofurans that is dibenzo[b,d]furan-1(9bH)-one substituted by acetyl groups at positions 2 and 6, hydroxy groups at positions 3 and 7 and methyl groups at positions 8 and 9b. ChEBI: Usnic acid is a member of the class of dibenzofurans that is dibenzo[b,d]furan-1(9bH)-one substituted by acetyl groups at positions 2 and 6, hydroxy groups at positions 3 and 7 and methyl groups at positions 8 and 9b. It has a role as an antifungal agent, a lichen metabolite and an acaricide. It is a member of dibenzofurans, a methyl ketone and a polyphenol.