{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T08:51:39Z","timestamp":1782204699916,"version":"3.54.5"},"reference-count":40,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2026,6,22]],"date-time":"2026-06-22T00:00:00Z","timestamp":1782086400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Usnic acid (UA), a prominent lichen secondary metabolite, exhibits a unique dual therapeutic profile in dermatology, though its clinical translation is limited by systemic hepatotoxicity and poor solubility. This review comprehensively evaluates the topical efficacy, molecular mechanisms, and advanced formulation strategies of UA enantiomers and UA-rich extracts. A literature search across PubMed, Scopus, and Google Scholar identified 36 original publications focusing on anti-melanoma activity, photoprotection, and tissue regeneration. In vitro studies demonstrate that UA induces apoptosis in resistant melanoma cell lines (A375, HTB-140) via extrinsic\/intrinsic pathways, with (\u2212)-UA effectively overcoming doxorubicin resistance. Conversely, in non-cancerous models, low concentrations of UA accelerate wound and burn healing by upregulating vascular endothelial growth factor (VEGF), stimulating fibroblast proliferation, and optimizing extracellular matrix remodeling while preventing hypertrophic scarring. To mitigate skin sensitization and systemic risks, advanced drug delivery systems\u2014including liposomes, nanoemulsions, chitosan nanogels, and electrospun scaffolds\u2014have been developed, significantly enhancing skin permeability and localized dermal retention. Ultimately, the development of bio-functionalized smart dressings and targeted nano-formulations represents the most viable path toward unlocking the full clinical potential of UA in modern dermatological and oncological care.<\/jats:p>","DOI":"10.3390\/molecules31122183","type":"journal-article","created":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T08:19:52Z","timestamp":1782202792000},"page":"2183","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Usnic Acid and Its Topical Use\u2014A Concise Review"],"prefix":"10.3390","volume":"31","author":[{"given":"Gabriela","family":"Siedlarczyk","sequence":"first","affiliation":[{"name":"Doctoral School of Medical and Health Sciences, Jagiellonian University Medical College, 16 \u0141azarza Str., 31-530 Cracow, Poland"},{"name":"Department of Pharmacognosy, Jagiellonian University Medical College, Medyczna 9, 30-688 Cracow, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1251-7192","authenticated-orcid":false,"given":"Irma","family":"Podolak","sequence":"additional","affiliation":[{"name":"Department of Pharmacognosy, Jagiellonian University Medical College, Medyczna 9, 30-688 Cracow, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5636-8646","authenticated-orcid":false,"given":"Agnieszka","family":"Galanty","sequence":"additional","affiliation":[{"name":"Department of Pharmacognosy, Jagiellonian University Medical College, Medyczna 9, 30-688 Cracow, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,6,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1362","DOI":"10.1111\/nph.18780","article-title":"How to Build a Lichen: From Metabolite Release to Symbiotic Interplay","volume":"238","author":"Pichler","year":"2023","journal-title":"New Phytol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"729","DOI":"10.1016\/S0031-9422(02)00383-7","article-title":"Molecules of Interest Usnic Acid","volume":"61","year":"2002","journal-title":"Phytochem"},{"key":"ref_3","first-page":"162","article-title":"Aktywno\u015b\u0107 Biologiczna i Farmakologiczna Kwasu Usninowego","volume":"3","author":"Galanty","year":"2012","journal-title":"Post. 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