Betulin, oleanolic acid, and betulinic acid are naturally occurring pentacyclic triterpenoids that have significant medicinal value. Considerable amounts of these triterpenoids are available in the outer bark of white birch.In this study, we used ultrasound-assisted extraction(UAE)to extract triterpenoids from birch bark rapidly and with high efficiency. Using high performance liquid chromatography(HPLC), three types of triterpenoids were separated and detected. We examined the differences among triterpenoids extracted from diploid versus tetraploid white birch. Then, we used factor analysis to screen out tetraploid white birches with comprehensively excellent performance. The results indicate that the optimum conditions for extraction include the use of ethanol as an extraction solvent, a solid-to-liquid ratio of 0.1 g/10 ml,ultrasonic power set at 100 W, a temperature of 60 °C and an extraction time of 15 min. A reversed-phase C18 column(4.6 mm × 250 mm × 5 lm) with a column temperature of 30 °C and the mobile phase composed of A(acetonitrile) and B(0.1 % aqueous phosphoric acid, v/v)at a flow rate of 0.5 ml/min were used, and the detection wavelength was 195 nm. No significant difference was observed between diploid and tetraploid white birch in terms of the content of three types of triterpenoids(at a confidence level of 0.05). As triterpenoid content, height,and DBH(diameter at breast height) are strongly interrelated, we used factor analysis to evaluate all individuals,and we screened out six plus trees with excellent comprehensive characters.
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