Usnea
Usnea
Brief Background: Usnea species are classified as fruticose lichens, which are a symbiosis of fungus and algae. Usnea grows on the bark and wood of coniferous (e.g., spruces, firs, and pines) and deciduous hardwood (e.g., oak, hickory, walnut, apple, and other fruit trees) host trees throughout the northern hemisphere in Asia, Europe, and North America.
Usnea has been used as a therapeutic agent in traditional Chinese medicine (TCM) for thousands of years. Usnea longissima is traditionally used as an oral extract in lung and upper respiratory infections and topically to treat surface infections or external ulcers. It is still used today in TCM in liquid extract and tincture form to treat tuberculosis lymphadenitis.
Usnic acid is a secondary metabolite uniquely found in all lichens and has been reported to have analgesic, antibacterial, antifungal, anti-inflammatory, antioxidant, antiplatelet/antithrombotic, antiviral, cytotoxic/antiproliferative, gastroprotective, weight loss, and wound healing activity.
Expert Opinion and Historic Precedent:
There are many species of Usnea lichen used in traditional herbal medicine, including Usnea amblyoclada, Usnea barbata, Usnea dasypoga, Usnea complanta, Usnea diffracta, Usnea fasciata, Usnea florida, Usnea ghattensis, Usnea hirta, Usnea longissima, Usnea rubiginea, Usnea siamensis, and Usnea subfloridana.
Usnea longissima, Usnea florida, Usnea diffracta, and Usnea barbata are the species most commonly used by North American medical herbalists, though other species may be used in traditional Chinese medicine formulations.
Usnea longissima is used in the treatment of gastric ulcer in Turkish local folk medicine and laboratory animal and in vitro studies support its gastroprotective activity
