Luque-Jurado Inmaculada, Quintanilla-López Jesús E, Lebrón-Aguilar Rosa, Soria Ana Cristina, Sanz María Luz
Instituto de Química Orgánica General (CSIC), Juan de la Cierva 3, 28006 Madrid, Spain.
Instituto de Química-Física 'Blas Cabrera' (CSIC), Serrano 119, 28006 Madrid, Spain.
Molecules. 2025 Jul 29;30(15):3181. doi: 10.3390/molecules30153181.
Birch ( sp.) bark is a well-known natural source of betulin (Bet) and betulinic acid (BAc), both of which have several bioactive properties. The evaluation of the extraction performance, relative to these lupane-type triterpenoids, provided by different biosolvents requires the development of a high-resolution and high-sensitivity liquid chromatography-mass spectrometry (LC-MS) approach that is also compatible with challenging extractants such as natural deep eutectic solvents (NADESs). In this work, an LC-MS method was developed and analytically characterized prior to its application for the quantitation of Bet and BAc in birch bark extracts obtained using conventional solvents (methanol and acetone) and biosolvents (limonene and NADESs). High precision (RSD < 3.3%), sensitivity (LOD: 23 ng mL and 29 ng mL for Bet and BAc, respectively), and accuracy (95-102% recovery) were found for this optimized method, using an acidulated water-methanol mixture as the mobile phase and sodium acetate as an additive. Extraction experiments conducted at 55 °C revealed that the NADESs, particularly thymol:1-octanol (1:1 molar ratio), outperformed the other solvents and were highly effective for the recovery of both triterpenoids (17.50 mg g and 0.92 mg g of Bet and BAc, respectively). This method can also be applied to similar extracts obtained from other biomasses.
桦树（某种）树皮是桦木醇（Bet）和桦木酸（BAc）的著名天然来源，这两种物质都具有多种生物活性。要评估不同生物溶剂针对这些羽扇豆烷型三萜类化合物的提取性能，就需要开发一种高分辨率和高灵敏度的液相色谱 - 质谱联用（LC - MS）方法，该方法还需与具有挑战性的萃取剂（如天然低共熔溶剂（NADESs））兼容。在这项工作中，开发了一种LC - MS方法，并在将其应用于定量分析用常规溶剂（甲醇和丙酮）以及生物溶剂（柠檬烯和NADESs）获得的桦树皮提取物中的Bet和BAc之前，对其进行了分析表征。使用酸化水 - 甲醇混合物作为流动相并添加醋酸钠，该优化方法具有高精度（相对标准偏差<3.3%）、高灵敏度（Bet和BAc的检测限分别为23 ng/mL和29 ng/mL）和高准确度（回收率为95 - 102%）。在55°C下进行的提取实验表明，NADESs，特别是百里酚:1 - 辛醇（摩尔比1:1），比其他溶剂表现更优，并且对两种三萜类化合物的回收率都很高（Bet和BAc分别为17.50 mg/g和0.92 mg/g）。该方法也可应用于从其他生物质中获得的类似提取物。
