Usnic acid (UA) is a secondary lichen metabolite extensively studied for the broad variety of biological features. The most interesting property of UA is its antimicrobial activity against Gram-positive bacteria growing either in planktonic or in biofilm mode. In this chapter, the most relevant studies assessing usnic acid activity against microbial biofilms have been summarized and the potential role of UA in the management of biofilm-based wound infections has been critically discussed. Additionally, an overview of the main strategies adopted so far to reduce drug toxicity and increase bioavailability is given in the perspective of a safe use of UA in the clinical management of infected wounds.
Keywords: Drug delivery; Microbial biofilm; Topical applications; Usnic acid; Wound infections.