熊果酸和齐墩果酸在枇杷叶枇杷花中的分布及动态变化

Distribution of Ursolic Acid and Oleanolic Acid in the Leaves and Flowers of Erobotrya japonica and Changes of Triterpene Acids Contents in the Leaves at Different Harvest Time

目的考察熊果酸(UA)、齐墩果酸(OA)在枇杷落叶、树叶和枇杷花中的分布,并探索其在枇杷叶中含量的动态变化规律。方法采用超高效液相色谱法(UPLC)测定熊果酸和齐墩果酸含量,色谱柱为Acquity BEH C18(2.1 mm×100 mm,1.7μm);流动相为甲醇-水-冰醋酸-三乙胺(体积比为250∶50∶0.10∶0.05),流速:0.25 mL·min-1;检测波长210 nm,柱温25℃。结果熊果酸和齐墩果酸在枇杷叶中含量显著高于枇杷花;落叶中熊果酸和齐墩果酸的含量高于树叶;一年里每个月采摘的枇杷叶中熊果酸和齐墩果酸的总含量变化范围在0.874%～0.988%。结论熊果酸和齐墩果酸在枇杷花、枇杷树叶和落叶中有不同的含量分布;不同采收时期枇杷叶中两个三萜酸总量随月份发生小幅波动,该波动主要来源熊果酸;研究结果支持2010年版《中国药典》对枇杷叶"全年均可采收"的规定;同时提示枇杷叶采收在自然落叶前后为佳。

OBJECTIVE To find out the distribution of ursolic acid and oleanolic acid in fresh leaves, fallen leaves and flowers of Eriobotrya japonica Lindl, and to explore the variation in contents of the triterpene acids in the leaves at different harvest time. METHODS Samples were collected in the campus once every month for 12 months. Determination of ursolic and oleanolic acid was carried out by ultra-high performance liquid cromatography （UPLC） with an acquity BEH ClsCOlumn（2. 1 mmx 100 mm, 1.7 μm）using methanol-water-glacial acetic acid-triethylamine（250： 50： 0. 10： 0. 05）as the mobile phase. The flow rate was 0. 25 mL · min^-1. The detection wavelength was set at 210 nm. RESULTS The contents of ursolic and oleanolic acids in Erobotrya japonica leaves were significantly higher compared with those in Erobotrya japonica flowers. The contents of the two triterpene acids in the fallen leaves were higher than those in the fresh leaves. The annual curves of dynamic changes of the two triterpene acids contents in Erobotrya japonica leaves showed that the total triterpene acids contents in the Erobotrya japonica leaves collected at the different time varied from 0. 874% to 0. 988%. CONCLUSION The distribution of the contents of ursolic and oleanolic acid in the fresh leaves, fallen leaves and flowers was different, and there was minor variation in the contents of the two tfiterpene acids in fresh Erobotrya japonica leaves collected at the different harvest time. This study therefore provides evidence that the Erobotrya japonica leaves included in Chinese Pharmacopoeia （2010 edition, Volume I） can be havested all the year round. Furthermore, the results suggest that the optimal harvesting time of Erobotrya japonica leaves should be between pre-defoliation period and defoliation period.