Obtaining of Triterpene Derivatives from Outer Birch Bark in the Extraction Process
17th International Scientific Conference "EcoBalt 2012": Book of Abstracts 2012
Aigars Pāže, Jānis Zandersons, Jānis Rižikovs, Galina Dobele, Baiba Spince, Vilhelmīne Jurkjāne, Ausma Tardenaka

One way for the rational use of natural raw materials and to save forest resources is to increase the degree of utilization of wood biomass. 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, it accumulates birch bark (BB) in the process, which does not find industrial application, and is often burned as fuel. BB comprises about 12.5 wt.% of the tree mass. Outer BB actually consists of a mixture of pentacyclic triterpenes (35–40 wt.%) and biopolyester suberin (45 wt.%) [1]. Betulin, betulinic acid and lupeol, representatives of triterpenes, are biologically active substances, whose efficiency can be enhanced by synthetic modification. Betulin in the outer BB powder form is used in folk-medicine as an anti-inflammatory agent. Its derivative, betulinic acid, features properties, regulating the development of live cells, which transform the metabolism process in malignant tumour cells in the self-annihilation direction. Betulinic acid selectively kills human melanoma cells while leaving healthy cells intact and is found to delay the progression of the HIV 1 infection, which eventually leads to AIDS, by preventing the formation of syncytia [2, 3]. Milled BB (≤ 2 mm) was pelletized on a laboratory flat die type pelletizer with holes of diameter 6 mm. The temperature equilibrium on the die was approximately 100oC. Extraction of triterpenes was carried out in Soxhlet apparatuses by the selected solvents (ethanol - water mixtures in the range of 75 to 95 vol%, acetone, cyclohexane and heptane) for 1-11 h. The components were identified with gas chromatography/mass spectroscopy by comparison of the spectra with those of the standards. The properties and composition of BB were evaluated to gain information for selecting a technology, convenient for obtaining triterpenes. Pelletization increased the outer BB bulk density up to 470 kg/m3. The yield of cyclohexane and heptane extractives was considerably lower than that in the case of acetone and ethanol. However, the more selective solubility eliminated the amount of undesirable substances, e.g., polyphenols, tannins, etc. from the total extract. The cutting age and small distinctions in the extraction composition of birch did not have a significant effect on the prospective betulin yield during an industrial scale production.

Triterpene, extraction,

Pāže, A., Zandersons, J., Rižikovs, J., Dobele, G., Spince, B., Jurkjane, V., Tardenaka, A. Obtaining of Triterpene Derivatives from Outer Birch Bark in the Extraction Process. In: 17th International Scientific Conference "EcoBalt 2012": Book of Abstracts, Latvia, Rīga, 18-19 October, 2012. University of Latvia: University of Latvia Press, 2012, pp.62-62. ISBN 978-9984-45-575-4. ISSN 1691-4112.

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