Usnic Acid and Its Derivatives in Pharmacological Applications

Usnic acid is a prominent lichen-derived secondary metabolite characterised by a dibenzofuran scaffold and noted for diverse biological activities, including antimicrobial, anti-inflammatory, antiviral, antioxidant and anticancer effects. Despite its broad therapeutic potential, applications have been constrained by poor aqueous solubility and occasional hepatotoxicity. In recent years, structural derivatisation—such as pyrazole and isoxazole substitutions—and salt formation have yielded analogues with improved pharmacokinetics and target specificity. Concurrently, innovative delivery systems, including polymeric micelles and nanocomposite gels, have enhanced solubility, permeability and controlled release. Mechanistic studies reveal that certain derivatives induce endoplasmic reticulum stress, disrupt mitochondrial respiration, generate reactive oxygen species and modulate cell-cycle regulators, underpinning antiproliferative and antimicrobial actions. Progress in elucidating metabolic pathways and detoxification routes has furthered understanding of safety profiles and dosage optimisation. Collectively, these advances underscore the global promise of usnic acid and its derivatives as leads for next-generation therapeutics, from anticancer agents to topical antimicrobials, while highlighting the imperative to balance efficacy with metabolic and toxicological considerations.

Research from Nature Portfolio

Potassium usnate, a water-soluble salt of usnic acid, demonstrates markedly enhanced bioavailability in tumour tissue, liver and plasma following oral administration. In colorectal cancer models, this derivative inhibited tumour growth and metastatic dissemination by downregulating epithelial–mesenchymal transition markers such as Twist, Snail and Slug, and suppressing metastasis-related gene networks. These findings establish a compelling proof of concept for salt-based modifications to overcome solubility barriers and deliver potent anticancer activity in vivo without compromising safety.

Usnic Acid and Its Derivatives in Pharmacological Applications publication trend

The graph below shows the total number of articles in usnic acid and its derivatives in pharmacological applications across all publications each year (not limited to Nature Index journals).

Technical terms

Dibenzofuran: A fused two-ring aromatic system that forms the core of usnic acid’s structure.

Bioavailability: The fraction of an administered dose of a compound that reaches the systemic circulation in an active form.

Polymeric micelle: A self-assembled colloidal structure composed of amphiphilic block copolymers used to encapsulate hydrophobic drugs for improved solubility and delivery.

Epithelial–mesenchymal transition (EMT): A biological process by which epithelial cells acquire migratory and invasive characteristics, often associated with cancer metastasis.

Endoplasmic reticulum (ER) stress: A cellular condition arising from the accumulation of unfolded or misfolded proteins in the ER, triggering adaptive or apoptotic pathways.

References

1. The pyrazole derivative of usnic acid inhibits the proliferation of pancreatic cancer cells in vitro and in vivo. Cancer Cell International (2023).
2. Nanocomposite gel containing usnic acid: Characterization and evaluation of the antibacterial efficacy on Staphylococcus epidermidis. International Journal of Pharmaceutics (2025).
3. Potassium usnate, a water-soluble usnic acid salt, shows enhanced bioavailability and inhibits invasion and metastasis in colorectal cancer. Scientific Reports (2018).
4. Advances in Research on Bioactivity, Toxicity, Metabolism, and Pharmacokinetics of Usnic Acid In Vitro and In Vivo. Molecules (2022).