Obtaining Pentacyclic Triterpenes from Outer Birch Bark

Abstract

One way for the rational use of natural raw materials and conservation of forest resources is to increase the degree of wood biomass utilization. A solution to this problem is directly related to improving the efficiency of biomass processing and reducing environmental pollution from industrial waste. Birch in the Northern hemisphere is a very widespread tree genus, which is extensively used in the furniture, pulp and plywood manufacture where, as a by-product, birch bark accumulates in the process. This material does not find industrial application, and is often burned as fuel. Outer birch bark consists of a mixture of pentacyclic triterpenes and bio polyester suberin. Betulin, betulinic acid and lupeol, representatives of triterpenes, are biologically active substances, the effects of which can be enhanced by synthetic modification. Pelletization increases the outer birch bark bulk density up to 470 kg/m3. The yield of cyclohexane and heptane extractives is considerably lower than those obtained with acetone and ethanol. However, the more selective solubility eliminates a range of undesirable substances, e.g., polyphenols, tannins, etc. from the total extract