Planta Med 2008; 74 - PC82
DOI: 10.1055/s-0028-1084600

Microwave – assisted extraction and ionic liquids used to obtain lichen metabolites from Pertusaria & Aspicilia species

S Bonny 1, S Tomasi 1, K Articus 1, A Bernard 1, J Boustie 1
  • 1EA 4090 „Substances Lichéniques et Photoprotection“, Lab. Pharmacognosy & Mycology, University of Rennes1, 2 Av. Pr. Léon Bernard, 35043 Rennes Cedex, France

Lichens are particular organisms, consisting of algae and fungi living in symbiosis. This symbiotic association results in the synthesis of original metabolites belonging predominantly to the group of depsides, depsidones and dibenzofuranes. These substances are of interest for the cosmetic and the pharmaceutical industry [1]. However, these compounds are often difficult to obtain due to the low availability of the lichen material. The main strategy is to use some innovative extraction methods which are „greener“ and permit the optimization of the extraction rate (qualitatively and quantitatively). We have performed various extraction protocols: heating reflux, MAE (microwave-assisted extraction) [2] and use of ionic liquid (IL) [3, 4], particularly with 1-ethyl-3-methylimidazolium ethyl sulfate and 1, 3-dimethylimidazolium methyl sulfate. Comparisons were mainly based on quantification of the content of norstictic acid of two lichen species, Aspicilia radiosa and Pertusaria pseudocorallina. The extracts were analyzed with appropriate TLC, HPLC and spectrophotodensitometer CAMAG ® procedures. Better results were obtained with MAE (tetrahydrofuran, three heating cycles of 5min, 150W). Thus, with optimized parameter settings, MAE showed a considerable reduction of both extraction time and solvent consumption, while maintaining qualitative and quantitative norstictic acid recovery relative to conventional extraction methods. The extract obtained with ILs, contained less compounds than usual solvent extraction. So, this method seems to be more selective. The combination of the MAE and the ILs technology [5] is in progress.

Acknowledgements: Sarah Bonny is particularly thankful to CAIMPEX for a financial support

References: 1. Boustie, J., Grube, M. (2005) Plant Gen. Res. 3: 1479–2621.

2. Chemat, S. et al. (2005) Chem. Eng. Process. 44: 1320–1326.

3. Alexei, A. et al. (2006)J. Nat. Prod. 69: 1653–1664.

4. Meindersma, G. W. et al. (2005) Fuel Process. Techn. 87: 59–70.

5. Du, F. Y. et al. (2007)J. Chrom. A 1140: 56–62.