Separation of betulin and its derivatives by high-performance liquid chromatography and their determination in extracts of some plants and chaga mushroom

Abstract The influence of conditions on the separation of betulin (BT), betulinic (BIA), and betulonic (BOA) acids by reversed-phase high-performance liquid chromatography (RP-HPLC) with isocratic elution was studied. It was shown that the order of peaks in chromatograms changed with varying the acetonitrile (ACN) content in the mobile phase, and a poor separation under certain conditions was observed. The highest peak resolution with minimal retention times was at a column temperature of 20 °C, flow rate of 0.25 ml/min, and 92.5% ACN in the mobile phase. The extracts from jujube (Ziziphus jujuba) dried fruit, chaga mushroom (Inonotus obliquus), and white birch bark (Betula pendula) were studied using the obtained conditions. For extracts from the first two sources, it was found that peaks of the compound studied interfered with unknown peaks. By varying the ACN content in the mobile phase with a small step from run to run and tracking the peaks, a baseline separation was achieved. The optimal % ACN in the mobile phase was 87 and 89 for the extracts from jujube and chaga mushroom, respectively. Jujube dried fruit was found to contain, in terms of dry weight of the jujube, 0.223 ± 0.008 mg/g of BIA and 0.044 ± 0.006 mg/g of BOA. Chaga mushroom studied contains 0.022 ± 0.004 mg/g of BT and 0.062 ± 0.009 mg/g of BIA. White birch bark contains 50.9 ± 0.7 mg/g of BT, 11.2 ± 0.3 mg/g of BIA, and 2.5 ± 0.3 mg/g of BOA. GRAPHICAL ABSTRACT