Advances in Research on Bioactivity, Toxicity, Metabolism, and Pharmacokinetics of Usnic Acid In Vitro and In Vivo

Abstract

Lichens are among the most widely distributed plants on earth and have the longest growth cycle. Usnic acid is an abundant characteristic secondary metabolite of lichens and the earliest lichen compound used commercially. It has diverse pharmacological activities, such as anti-inflammatory, antibacterial, antiviral, anticancer, antioxidant, and photoprotective effects, and promotes wound healing. It is widely used in dietary supplements, daily chemical products (fodder, dyes, food, perfumery, and cosmetics), and medicine. However, some studies have found that usnic acid can cause allergic dermatitis and drug-induced liver injury. In this paper, the bioactivity, toxicity, in vivo and in vitro metabolism, and pharmacokinetics of usnic acid were summarized. The aims were to develop and utilize usnic acid and provide reference for its future research.

Restoring Colistin Sensitivity and Combating Biofilm Formation: Synergistic Effects of Colistin and Usnic Acid against Colistin-Resistant Enterobacteriaceae

“…A significant synergistic effect of the COL/UA combination on all tested isolates was demonstrated via checkerboard assays and time-kill curve tests. Due to the dose-dependent toxic side effects of UA, its medical application is limited . Our study yielded effective results with a reduced dosage of UA, which reflects the potential use of this combination in future systematic research.…”

“…25 Hence, there is a growing interest in synthesizing UA derivatives or developing combination therapies with conventional antibiotics. 26 Bernardetta Segatore et al reported the synergistic effect of UA in combination with gentamicin against MRSA. 27 In addition, the combined action of UA and norfloxacin in disrupting cell membrane stability and metabolic homeostasis has been shown to synergistically combat MRSA.…”

“…Furthermore, UA has been reported to inhibit the biofilm formation of S. aureus , P. aeruginosa , and Candida albicans , thereby presenting intriguing prospects for its potential use in the prevention or treatment of biofilm-based infections . Hence, there is a growing interest in synthesizing UA derivatives or developing combination therapies with conventional antibiotics . Bernardetta Segatore et al.…”

“…The thigh infection model was established by intramuscularly injecting a 100 μL suspension of E. coli DC4887 (1.5 × 10 8 CFU/mL) into each posterior thigh muscle of each mouse. After a 2-h incubation period, the mice received intraperitoneal administrations of COL either alone or in combination with UA, with repeated administrations after 12 h. 26 After a 24-h period, the mice were euthanized, and the bacterial load in the posterior thigh was quantified by enumerating the colony-forming units (CFUs) in the homogenates.…”

PCL/Collagen/UA Composite Biomedical Dressing with Ordered Microfiberous Structure Fabricated by a 3D Near-Field Electrospinning Process

“…Usnic acid (UA), also known as lichen acid, widely exists in lichen plants and is a natural furan antibiotic, which has been partially used in cosmetics, health products, and bacteriostatic agents [ 26 , 27 ]. Moreover, UA has good antibacterial effect and biological activity in vitro, and can effectively inhibit the growth of E. coli , S. thermophilus , S. pyogenes, and other bacteria [ 28 ].…”