Abstract
The submitted invention concerns the purification of betulin and lupeol from triterpene extract from birch bark. The purification method involves the next steps: a) dry birch bark extract is dissolved in hot acetone, b) acetone solution is filtered and thins up by water with formation of suspension, which is filtered, washed by distilled water and dried, c) dry precipitate from step b) is dissolved in hot ethanol, the solution of CaCl2 in hot ethanol is added and then the solution of NaOH in hot ethanol is added with stirring.
After complete precipitation of insoluble Ca(OH)2 containing acidic and similar (e.g. phenolic) impurities, the solution is filtered and triterpenes are crystallized in cold, crystals are washed by cold ethanol and dried, d) crystalline precipitate from step c) is dissolved in hot chloroform and betulin is precipitated by adding of petroleum ether or another hydrocarbons (C5 - C8) whereas lupeol stays dissolved in solution. Precipitate (betulin) is filtered and washed by petroleum ether and dried, the filtrate is evaporated and dried (lupeol).
This step can be repeated for better separation of these two triterpenes, e) betulin or lupeol from step d) is dissolved in chloroform and solution is filtered through silica gel, the filtrate is evaporated and dried. Betulin or lupeol can be recrystallized from ethanol.
Betulin and lupeol prepared by this method (with one repeating of the step d)) is of more than 99% (betulin) or 95% (lupeol) purity.