Naturwissenschaften

, Volume 89, Issue 4, pp 137–146

A review on usnic acid, an interesting natural compound

  • Moreno Cocchietto
  • Nicola Skert
  • Pier Nimis
  • Gianni Sava
Review Article

DOI: 10.1007/s00114-002-0305-3

Cite this article as:
Cocchietto, M., Skert, N., Nimis, P. et al. Naturwissenschaften (2002) 89: 137. doi:10.1007/s00114-002-0305-3

Abstract.

Lichens are a world-widespread consortium of fungal and photosynthetic partners. Usnic acid is one of the most common and abundant lichen metabolites, well known as an antibiotic, but also endowed with several other interesting properties. This review summarises the most relevant studies on usnic acid, focusing on a number of biological activities in different fields. On the basis of the existing literature, usnic acid seems to be an exclusive lichen product. No synthetic derivatives more effective than the natural form are known. Both the (+) and (–) enantiomers of usnic acid are effective against a large variety of Gram-positive (G+) bacterial strains, including strains from clinical isolates, irrespective of their resistant phenotype. Of particular relevance is the inhibition of growth of multi-resistant strains of Streptococcus aureus, enterococci and mycobacteria. The (+)-usnic acid enantiomer appears to be selective against Streptococcus mutans without inducing perturbing side effects on the oral saprophyte flora. On the other hand, the (–)-usnic acid enantiomer is a selective natural herbicide because of its blocking action against a specific key plant enzyme. Other recognised characteristics of usnic acid are ultraviolet absorption and preserving properties. The toxicology, the in vitro anti-inflammatory effects and the mechanism of action of usnic acid need to be investigated in greater detail in order to reach clinical trials and to allow further applications. Furthermore, more research is needed to make possible intensive lichen culture, in order to produce large quantities of lichen substances for pharmaceutical, cosmetic and agricultural purposes. Some biological aspects, i.e. the possible biological roles of usnic acid, are discussed.

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Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  • Moreno Cocchietto
    • 1
  • Nicola Skert
    • 2
  • Pier Nimis
    • 2
  • Gianni Sava
    • 1
  1. 1.Callerio Foundation-Onlus, Institute of Biological Research, via A. Fleming 22–31, 34127 Trieste, Italy
  2. 2.Department of Biology, University of Trieste, via L. Giorgieri 10, 34127 Trieste, Italy

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