Analysis and evaluation of triterpenoids in tetraploid birch (Betula).

Betulinic acid, oleanolic acid and betulin are three pentacyclic triterpenoids in birch bark with high contents and a variety of medicinal values. In this study, we used ultrasonic-assistant measure to extract triterpenoids from birch bark rapidly with high efficiency. Using HPLC, we separated and detected the three kinds of triterpenoids. Then, we examined the differences in contents of three triterpenoids between two kinds of birches by building violin plots and star plots. Finally, we applied factor analysis method to screen the tetraploid birches with excellent comprehensive traits. The HPLC assay was performed using a reversed-phase C18 column (4.6 mm 250 mm 5 m) with a column temperature of 30 ℃. The mobile phase was composed of acetonitrile and 0.1% aqueous phosphoric acid with a flow rate of 0.5 mL/min and detection wavelength of 195 nm. There were significant differences in contents of betulinic acid and betulin between the two kinds of tetraploid birches at the confidence level of 0.10, and also a significant difference in oleanolic acid content at the confidence level of 0.05. The contents of three triterpenoids in B. platyphylla B. pendula were always higher than that in B. platyphylla. The results indicated that there was a significantly positive correlation among contents of three triterpenoids. Analysis revealed that the correlation coefficient was the highest (0.911) between betulinic acid and betulin and the lowest (0.631) between oleanolic acid and betulin. With factor analysis we obtained the following comprehensive evaluation formula for individual birch plants:F=48.620%F1 + 21.080%F2 + 21.075%F3, and screened out the individual plants with excellent comprehensive characters. The three top-scorer individuals of B. platyphylla were Nos. 4126, 4123 and 4125, and those of B. platyphylla B. pendula were Nos. 4202, 4204 and 4208.