Review of the biological properties and toxicity of usnic acid

Abstract

Since its first isolation in 1844, usnic acid [2,6-diacetyl-7,9-dihydroxy-8,9b-dimethyl-1,3(2H,9bH)-dibenzo-furandione] has become the most extensively studied lichen metabolite and one of the few that are commercially available. Lichens belonging to usnic acid-containing genera have been used as crude drugs throughout the world. There are indications of usnic acid being a potentially interesting candidate for such activities as anti-inflammatory, analgesic, healing, antioxidant, antimicrobial, antiprotozoal, antiviral, larvicidal and UV protection. However, some studies reported the liver toxicity and contact allergy. Thus, further studies are needed to establish the efficacy and safety of usnic acid.

Anti-angiogenic and antiproliferative properties of the lichen substances (-)-usnic acid and vulpinic acid

“…1000 presently known) derived from fungal metabolism have antimicrobial, antiviral, antiprotozoal, antiproliferative, antitumor, antiinflammatory, anti-pyretic, analgesic, photoprotective, enzyme inhibitory and anti-angiogenic properties [4][5][6][7][8]. Usnic acid, a dibenzofuran derivative, is one of the most frequent and most studied lichen metabolites [9]. It is found commonly in many lichen species [5,10].…”

Enantioselective activity of usnic acid: a comprehensive review and future perspectives

“…Enantiomers do not substantially differ in terms of certain physical properties, like solubility, melting point or spectroscopic characteristics (Ö zek et al 2010), but may have a different aroma or flavour (Silva et al 2012) and also may reveal differences in their biological and pharmacological activity (Nguyen et al 2006). The current, published reviews on usnic acid have focused mainly on the different aspects of its activity (Shrestha and St. Clair 2013;Araújo et al 2015;Cimmino et al 2018), but not on its enantiospecificity. Although a lot of experimental results describe a wide range of pharmacological properties of usnic acid, it is still not clear if there are any differences between the activities of its enantiomers.…”

Lichens as a source of chemical compounds with anti-inflammatory activity

“…1). The metabolite, known for its antibacterial activity for a long time, is subject to numerous experiments which objective is the discovery of more and more aspects of the biological activity [15]. One line of the work is to study the anti-inflammatory activity of the compound, as presented by Huang et al [16].…”