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A. Ressmann, P. Gärtner, K. Schröder:
"Biomass Dissolution with Ionic Liquids: Improved Isolation of the Pharmaceutically Active Steroid Betulin";
Poster: EUCHEM 2012 Conference on Molten Salts and Ionic Liquids, Celtic Manor, Newport, Wales; UK; 05.08.2012 - 10.08.2012; in: "EUCHEM 2012 Conference on Molten Salts and Ionic LIquids", (2012).

To date, extraction of active ingredients from biomass is mainly performed in extraction processes using large volumes of volatile and combustible organic solvents. Ionic Liquids represent a new class of solvents that can dissolve biomass and thus might provide a safer and more efficient isolation strategy for the isolation of valuable active compounds from crude biomass. ,
Betulin (lup-20(29)-en-3β,28-diol, 1, Fig. 1) is a naturally occurring triterpene alcohol with a lupane skeleton found in up to 30 wt% in birch bark. Betulin and its derivates show antitumor, anti-HIV, antiviral, antibacterial, anti-inflammatory and antimalarial activities. However, its current isolation process is inefficient with a low isolation yield of 10-20 wt% and requires large amounts of volatile solvents.
Herein, we present an ionic-liquid-based isolation strategy for the active ingredient betulin from birch bark. Based on an initial HPLC screening, we found that the use of ionic liquids could significantly improve the extraction yield of up to Betulin. A simple and scalable isolation procedure allowed isolating Betulin in excellent purities of up to 98% and recovery of the ionic liquid for four times with only small decrease in performance.