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  • Extraction of betulinic acid and betulin from white birch bark [Elektronski vir]
    Perva, Amra ...
    Birch tree (family Betulaceae) grows mostly in northern parts of hemisphere and requires moist, well-drained, sandy loam soils. The medicinal parts include the young leaves, twigs, catkins and bark. ... Birch bark, which contains oils, tannins, phytosterol, betulin and betulinic acid among the principal extractives, is a low-value waste product in forest industry. The outer and inner bark of birch tree differ considerably chemically; outer bark is rich in triterpene compounds, and the inner bark contains extractable sugars, tannins and other. The best-known and important extractive component of birch bark is betulin, which gives birch bark its white colour and constitutes 20 to 30 % of the content of outer bark. Betulin, also known as betulinol or birchcamphor is a natural triterpene product, and has anti-inflammatory, hepatoprotective, antitumoral, antiviral and other valuable properties. Betulinic acid, a pentycyclic triterpene, is derived from the equivalent alcohol, betulin, and is found to induce apoptosis, cell death in melanoma cells without impacting healthy tissue. Our study was mainly focused on the isolation of betulin and betulinic acid from birch bark throughout obtaining raw extracts by reflux or Soxhlett extraction with different solvents. Birch bark (Betula pendula) was collected in autumn and dried in air, after which it was divided into three partsČ outer bark, and two layers of inner bark. The three fractions were milled separately. Samples of outer bark were in the form of white shreds, while inner bark, in the form of reddish chunks, was separated into two samples: 1st layer as a mixture of outer and inner bark and 2nd layer as the deep inner bark. Both samples of inner bark were separated using a sieve mesh of size 0,5 and 1,00 mm additionally to performing a sieve analysis. The efficiency of commonly used solvents for the extraction of betulinic acid and betulin from outer and two layers of inner bark were compared. The solvents used were hexane, dichloromethane, diethyl ether, methanol, acetone and ethanol. Raw extracts obtained were analysed for betulin and betulinic acid using high performance liquid chromatography by an isocratic method and the results given as weight percentage on dry basis. A comparison of betulin and betulinic acid content in extracts obtained from three different layers of birch bark was achieved. A decrease of extracts quality regarding the content of investigated active ingredients was observed along the bark depth. The corresponding yield of extraction was also dependenton the bark sample.
    Source: CHISA 2002 [Elektronski vir] (6 f.)
    Type of material - conference contribution
    Publish date - 2002
    Language - english
    COBISS.SI-ID - 7326486

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