Skyherb has developed a method of isolating betulin and betulinic acid from birch bark and has successfully been producing commercial quantities for several years. Product Description: Resources: Birch bark Main Components: Betulin, Betulinic acid, Betulin diacytate Skyherb can provide the specifications of birch bark extract as follow: Betulin (CAS NO.: 473-98-3): 70%, 90%, 98%, 99% Betulinic acid (CAS NO.: 472-15-1): 50%, 90%, 98% Betulin diacetate (CAS NO.: 1721-69-3): 98% Please feel free to contact us for more details: sales[at]skyherb dot cn