Subcritical extraction of birch bark pentacyclic triterpenes

Natural pentacyclic triterpenes were extracted from birch bark with subcritical solvents. The influence of the solvent nature, temperature, and the number of extraction cycles on the efficiency of the process was studied. Using methanol at 100 A degrees D provides the highest tri-terpene extraction rate. Bark extracts prepared using various solvents were analyzed for chemical composition and antioxidant activity.