Planta Med 2010; 76 - LS1
DOI: 10.1055/s-0030-1268213

HPLC determination of usnic acid content in different extracts of Usnea barbata

SM Đorðević 1, J Ivanović 2, J Kukić-Marković 3, S Petrović 3, I Žižović 2, VM Tadić 1, GM Marković 1
  • 1Institute for Medicinal Plant Research „Dr Josif Pančić“, 11000 Belgrade, Serbia
  • 2Faculty of Technology and Metallurgy, University of Belgrade, Karnegijeva 4, 11120 Belgrade, Serbia
  • 3Department of Pharmacognosy, Faculty of Pharmacy, University of Belgrade, Vojvode Stepe 450, 11221 Belgrade, Serbia

Lichens are important sources of biologically active compounds. Beard lichen, Usnea barbata L. (Parmeliaceae) grows on the bark of host trees in the Northern hemisphere of Europe, Asia and America [1]. Lichens containing usnic acid are traditionally used in China and other parts of the world, for medicinal and cosmetic purposes, as well as in homeopathy. Usnic acid exhibits antimicrobial, antiviral, antiprotozoal, antiproliferative, anti-inflammatory, analgesic and antipyretic activities [2].

In this work, usnic acid content in U. barbata extracts obtained by different extraction methods was determined. Extractions with supercritical CO2 were carried out in the Autoclave Engineers Screening System (USA) at pressure of 30 MPa and temperatures of 40°C (sample 1) and 60°C (sample 2). Ethanol extracts (70% V/V) were prepared by maceration, percolation and continuous extraction in Soxhlet apparatus (samples 3, 4, and 5, respectively). Yields of dry extracts were: 0.60%, 0.38%, 3.13%, 4.35%, and 10.18% (samples 1, 2, 3, 4 and 5, respectively). Usnic acid content was determined using validated HPLC-DAD method. Usnic acid was used as a standard substance. Content of usnic acid in samples 1, 2, 3, 4 and 5 was 36.49%, 59.48%, 0.25%, 0.18%, and 3.59%, respectively.

It was shown that the extraction method has a great influence on the extract yield as well as usnic acid content. Our results confirmed superior performances of supercritical CO2 extraction, that ensure producing purified extracts rich in usnic acid, which can be applied in different medicinal and cosmetic products.

Acknowledgements: The authors wish to thank Serbian Ministry of Science for financial support project No. TR 20049, TR19037 and 143012.

References:

[1] Engel, K. et al. (2007) Journal of Photochemistry and Photobiology B: Biology 89:9–14.

[2] Ignollfsdottir, K (2002) Phytochemistry 61:729–736.