Ionic Liquids Coupled to Microwave Irradiation: an Efficient and Selective Process for Secondary Lichens Metabolites Extraction

Lichens are particular organisms, consisting of a cyanobacterial or/and an algal symbiotic partnership with a fungus. Their secondary metabolites are usually original molecules which are not found in other types of organisms. These substances are of interest for cosmetics and pharmaceutics as a variety of activities have been reported, antibiotic, anti-inflammatory, antioxidant, UV-A and UV-B filters. The standard methods for the extraction of these secondary metabolites proceed through time consuming, heat reflux protocols with volatile organic solvents. The aim of the current study is to develop innovative methods to accelerate (qualitatively and quantitatively) the selective extraction of lichen compounds. After optimization of microwave assisted extraction (MAE), we applied this method on Pseudevernia furfuracea using various ionic liquids (ILS). This extraction was compared to the classical extraction using Volatile Organic Solvents (VOCs). The efficiencies of the extraction methods are evaluated using TLC coupled to a Camag® spectrophotodensitometer and HPLC analysis.