Critical Assessment of the Anti-Inflammatory Potential of Usnic Acid and Its Derivatives—A Review

Abstract

Inflammation is a response of the organism to an external factor that disrupts its natural homeostasis, and it helps to eliminate the cause of tissue injury. However, sometimes the body’s response is highly inadequate and the inflammation may become chronic. Thus, the search for novel anti-inflammatory agents is still needed. One of the groups of natural compounds that attract interest in this context is lichen metabolites, with usnic acid (UA) as the most promising candidate. The compound reveals a broad spectrum of pharmacological properties, among which anti-inflammatory properties have been studied both in vitro and in vivo. The aim of this review was to gather and critically evaluate the results of the so-far published data on the anti-inflammatory properties of UA. Despite some limitations and shortcomings of the studies included in this review, it can be concluded that UA has interesting anti-inflammatory potential. Further research should be directed at the (i) elucidation of the molecular mechanism of UA; (ii) verification of its safety; (iii) comparison of the efficacy and toxicity of UA enantiomers; (iv) design of UA derivatives with improved physicochemical properties and pharmacological activity; and (v) use of certain forms or delivery carriers of UA, especially in its topical application.

Pleiotropic Potential of Evernia prunastri Extracts and Their Main Compounds Evernic Acid and Atranorin: In Vitro and In Silico Studies

“…Studies have shown that lichen metabolites contain biologically active compounds that possess anti-COX-2 activity [ 53 , 54 , 55 ]. Based on the results of in vivo studies, lichen extracts can inhibit the inflammatory response in animal tissue [ 56 ].…”

Electrospun Nanofibrous Mesh Based on PVA, Chitosan, and Usnic Acid for Applications in Wound Healing

“…Usnic acid (UA), a dibenzofuran produced from lichen, is one of them [ 113 ]. Usnic acid is able to reduce the inflammation related to burns and to encourage wound closure through keratinocyte monolayers [ 64 , 114 ].…”

“…Studies showed that UA has an antimicrobial effect against anaerobic bacteria such as Bacteroides ruminicola ssp. Brevis , Bacteroides fragilis , Bacteroides vulgatus [ 63 , 64 ], Clostridium perfringens [ 63 , 64 , 65 ], Propionibacterium acnes [ 63 , 64 , 65 ], Bacteroides thetaiotaomicron [ 63 , 64 ], Gram-positive bacteria such as Enterococcus faecium [ 63 , 64 ], Enterococcus faecalis [ 63 , 64 , 65 ], Staphylococcus aureus [ 64 , 65 , 66 , 67 ], S. mutans [ 68 , 69 , 70 , 71 ], S. epidermidis [ 63 , 65 , 72 ], Streptococcus pyogenes [ 63 , 64 , 73 , 74 ], Streptococcus pneumoniae [ 64 , 65 ], Gram-negative bacteria such as Escherichia coli , Haemophilus influenza , Pseudomonas aeruginosa , and Mycobacteria such as M. aurum , M. avium , M. smegmatis , M. tuberculosis var. bovis , M. tuberculosis var.…”

“…bovis , M. tuberculosis var. homini [ 64 ]. Although all these properties make it suitable as a wound-healing agent, there are some limitations in terms of its low water solubility that researchers have tried to overcome by using more soluble salt forms, encapsulating them into liposomes in collagen and gelatin films, including them into β-cyclodextrins, or encapsulating them in electrospun fibers [ 61 ].…”

The effect of Usnea longissima extract on chemotherapy-associated multi-organ damage in rats

“…It has been stated that Usnea longissima extracts have strong antioxidant effects [21]. Also, it has been shown that usnic acid, a metabolite of Usnea longissima, inhibits in ammation both in vitro and in vivo [22]. This information obtained from the literature suggests that extracts obtained from Usnea longissima may be useful in the treatment of doxorubicin and cisplatin-related multi-organ toxicity.…”