Crystalline, yellow solid. Insoluble in water; slightly soluble in
alcohol and ether.
Usnic acid is an enzyme inhibiting antitumor agent.
Usnic acid is a major metabolite from a number of lichen and fungal species and is perhaps one of the longest known microbial metabolites, first isolated in 1844. Usnic acid exhibits a broad range of biological activity, indeed it is easier to list the bioassays in which it does not exhibit activity. More often than not, potency is low and of limited value. Usnic acid is an important metabolite for dereplication in discovery research programs.
ChEBI: 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.
Usnic acid is a component of lichens, also used as a
topical antibiotic. Allergic contact dermatitis from
lichens occurs mainly occupationally in forestry and
horticultural workers, and in lichen pickers.
This very weak acid is the natural form which is recrystallised from Me2CO, MeOH or *C6H6. At 25o it is soluble in H2O (<0.01%), Me2CO (0.77%), EtOAc (0.88%), MeOCH2CH2OH (0.22%) and furfural (7.32%). [Curd & Robertson J Chem Soc 894 1937, Barton & Brunn J Chem Soc 603 1953, resolution: Dean et al. J Chem Soc 1250 1953, synthesis: Barton et al. J Chem Soc 538 1956, Beilstein 18/5 V 586.]
