Xu Xiao-Hong, Su Qing, Zang Zhi-He
School of Pharmacy, Chengdu Medical College, Chengdu 610083, People's Republic of China.
J Pharm Anal. 2012 Jun;2(3):238-240. doi: 10.1016/j.jpha.2012.01.006. Epub 2012 Feb 8.
Oleanolic acid (OA) and ursolic acid (UA) are isomeric triterpenic acids and only one methyl's position is different between them. OA and UA always exist in the same plant, so it is difficult to separate them when determining contents by RP-HPLC. In this study, a very simple mobile phase for HPLC was developed to simultaneously determine UA and OA, and the factors affecting separation were also discussed. The mobile phase is methanol: water (95:5) with flow rate 0.4 mL/min. The retention time for OA and UA was 20.58 and 21.57 min, respectively, the resolution was 1.61. The average contents of OA and UA of three Loquat leaves sets were 1.4 mg/g and 5.6 mg/g, respectively. Regarding the HPLC, we found that changing mobile phase, adjusting the pH value or adding ion-pairing agent could not affect the separation between UA and OA greatly. While adjustment of the flow rate and column temperature could improve the resolution greatly.
齐墩果酸（OA）和熊果酸（UA）是同分异构的三萜酸，它们之间仅一个甲基的位置不同。OA和UA总是存在于同一植物中，因此采用反相高效液相色谱法（RP-HPLC）测定含量时很难将它们分离。在本研究中，开发了一种非常简单的HPLC流动相来同时测定UA和OA，并讨论了影响分离的因素。流动相为甲醇：水（95:5），流速为0.4 mL/min。OA和UA的保留时间分别为20.58和21.57分钟，分离度为1.61。三组枇杷叶中OA和UA的平均含量分别为1.4 mg/g和5.6 mg/g。关于HPLC，我们发现改变流动相、调节pH值或添加离子对试剂对UA和OA之间的分离影响不大。而调节流速和柱温可大大提高分离度。
