UHPLC–Q-ToF-MS-guided enrichment and purification of triterpenoids from Centella asiatica (L.) extract with macroporous resin

The aim of the study is to standardize a simple and an effective extraction method for industrial preparation of Centella asiatica (L.) extract rich in triterpenoids. Macroporous resin purification process was adapted to enrich the triterpenes extracted from the herb. A sensitive analytical method with good resolution, linearity, and a shorter run time of 10?min was developed in ultra high-performance liquid chromatography–quadrupole-time-of-flight mass spectrometer for monitoring the triterpene (madecassoside, asiaticoside, madecassic acid, and asiatic acid) content at each stage of the extraction process. The standardized process could enrich the triterpene, madecassoside in the product up to a purity of 72.51% with overall recovery of the compound to 90.79%. A purified form of asiaticoside with a purity of 85% was obtained by dealcoholization and precipitation process exploiting the differential water solubility of the two major triterpenes. The binding and recovery of the aglycones (madecassic acid and asiatic acid) were observed to be poor, and hence the overall recovery of aglycones by this process was found to be very low. The purified triterpenoids were also confirmed by the ¹H NMR. Thus, the results suggest that the standardized process can be converted to industrial-scale preparation of high-value C. asiatica (L.) products rich in madecassoside or asiaticoside.     

Development and validation of high-performance liquid chromatography/electrospray ionization mass spectrometry for assay of madecassoside in rat plasma and its application to pharmacokinetic study

A rapid, sensitive and specific high-performance liquid chromatography/electrospray ionization mass spectrometric (LC-ESI-MS) method was developed and validated for the quantification of madecassoside, a major active constituent of Centella asiatica (L.) Urb. herbs, in rat plasma. With paeoniflorin as an internal standard (IS), a simple liquid-liquid extraction process was employed for the plasma sample preparation. Chromatographic separation was achieved within 6 min on a Shim-pack CLC-ODS column using acetonitrile and water (60:40, v/v) containing 0.1% (v/v) formic acid as the mobile phase. The detection was performed by MS with electrospray ionization interface in negative selected ion monitoring (SIM) mode. The linear range was 11-5500 ng/mL with the square regression coefficient (r(2) ) of 0.9995. The lower limit of quantification was 11 ng/mL. The intra- and inter- day precision ranged from 4.99 to 9.03%, and the accuracy was between 95.82 and 111.80%. The average recoveries of madecassoside and IS from spiked plasma samples were >92%. The developed method was successfully applied to the pharmacokinetic study of madecassoside in rats after an oral administration.     

齐墩果烷型和乌苏烷型五环三萜同分异构体配位色谱法分离机理（英文）

本文主要研究了配位色谱法分离齐墩果烷型和乌苏烷型五环三萜同分异构体的分离机理。基于计算模拟分析,β-环糊精（β-CD）和其衍生物为适宜的配位剂。采用HPLC法测定了包合物的表观形成常数,并制备了asiaticoside-B与β-CD包合物。实验结果显示:流动相中添加葡萄糖基-β-环糊精（Glu-β-CD）时,同分异构体的分离度为11.95,比添加β-CD或添加甲基-β-环糊精（DM-β-CD）时（分别为9.61和9.89）都略高些。假定五环三萜类化合物与β-CD形成1：1的包合物,对于asiaticoside-B,流动相中添加Glu-β-CD时,表观形成常数（K_F）为2534 L/mol,比添加β-CD或添加DM-β-CD时（分别为1467和1373 L/mol）都略大些。根据asiaticoside-B与β-CD包合物的红外光谱解析及计算模拟,推测asiaticoside-B的E环上甲基部分进入了β-CD的空腔内,而其羰基基团没有进入β-CD的空腔内,其糖苷部分与亲水性的β-CD空腔外部形成氢键作用力。因此,配位色谱法分离齐墩果烷型和乌苏烷型五环三萜同分异构体的分离机理可以推测如下：齐墩果烷型和乌苏烷型五环三萜同分异构体E环上甲基的不同空间位阻导致了同分异构体的不同色谱分离行为。     

制备型高效液相色谱法从积雪草提取物中分离纯化积雪草甙和羟基积雪草甙对照品

积雪草甙和羟基积雪草甙是积雪草及其相关制品质量控制的两个指标成分,本研究利用制备型高效液相色谱从积雪草提取物中同 时分离纯化得到这两个成分。对制备色谱的流动相组成、流速、进样量和检测波长等制备参数进行了优化。采用的色谱柱为C18柱(50 mm×200 mm,5 μm);流动相为甲醇-水(体积比为60∶40),流速100 mL/min;二极管阵列检测器在220 nm检测;进样体积为1.5 mL。在20 min的运行时间内,积雪草甙和羟基积雪草甙与干扰成分得到很好的分离,产品纯度达到98%以上。此方法具有快速高效、产品纯度高的 特点,可以用于制备积雪草甙和羟基积雪草甙对照品。