Introduction
Pseudevernia furfuracea, a lichen used classically for cosmetic applications, contains interesting metabolites possessing antimicrobial and anti‐inflammatory or antioxidant properties.
Objectives
Ionic liquid combined to microwave‐assisted extraction (IL–MAE) was successfully applied for metabolites extraction from Pseudevernia furfuracea.
Materials and methods
Three imidazolium and pyridinium‐based ionic liquids (ILs): 1,3‐dimethylimidazolium methylsulphate [C1C1Im][MeSO4], 1‐ethyl‐3‐methylimidazolium ethylsulphate [C2C1Im][EtSO4], and N‐ethylpyridinium ethylsulphate [C2Py][EtSO4] were assessed for this process. The efficiency of the extraction method was evaluated using thin‐layer chromatography (TLC) coupled to a Camag® spectrophotodensitometer and using high‐performance liquid chromatography (HPLC) analysis.
Results
ILs under MAE showed extraction time efficiency (15 min vs. 24 h for conventional heating) and high selectivity in extracting the targeted metabolites: atranorin (AT), methyl‐β‐orcinol carboxylate (MOC), fumarprotocetraric acid (Fum. Ac.), and physodic acid (Phys. Ac.) despite the increased degradation of AT under MAE. We showed a tunable selectivity of ILs towards extracting metabolites by changing anion or cation due to the modification of the interaction between the IL and the metabolites. While [C2Py][EtSO4] was the most efficient IL and could extract all the targeted metabolites, [C2C1Im][EtSO4] was the most selective. It fully extracted AT and partially Fum. Ac. Moreover, the lichen prepared by mixing procedure provided AT and Fum. Ac. more than the milled one. A 100 times scale‐up extraction was successfully performed on mixed samples with full IL recycling after back extraction.
Conclusion
IL–MAE is reliable for lichen metabolites extraction. The method is reproducible, scalable, with possible IL recycling, opening the door for potential industrial applications.