Simultaneous determination of triterpenes, flavonoids and phenolic compounds in Prunella vulgaris by capillary zone electrophoresis with running buffer modifiers

Prunella vulgaris L. (Labiatae), also known as the ‘‘self-heal’’, is a perennial plant commonly found in China and Europe. It has long been used as a folk medicine for alleviating sore throat, reducing fever in traditional European and Chinese medicine. It was also used as a material to manufacture functional beverage. The modern pharmacological studies reveal that the methanol or water extract of this herb have many effect including systemic anaphylaxis inhibition (1); antihyperglycemic activity (2); Immune modulation (3); etc. To further explore the biological effects and potential application of this herb, quality control of it is very important. A cyclodextrin-modified capillary zone electrophoresis (CD-CZE) method was established for the separation and determination of ursolic acid, oleanolic acid, betulinic acid (three structure isomers), caffeic acid, p-courmaric acid, rosmarinic acid, rutin and quercetin in Prunella vulgaris L. The effect of β-cyclodextrin, methanol content, borax concentration and pH were investigated in detail. These eight components were well separated from each other within 20 min with running buffer of 40 mM borax (pH 9.4) containing 2 mM β-cyclodextrin and 4% methanol (V/V), voltage of 25 kV, temperature of 25oC and detection wavelength of 214 nm. Benzoic acid was used as an internal standard to improve the CE performance. The RSD of migration time ranged from 0.25 to 0.74% while those of the peak area ratios (analytes perk area/ internal standard perk area) ranged from 2.17 to 4.61% for six determinations of analytes at the concentration of 25 μg mL-1. The correlation coefficients of the calibration curves of analytes were all >0.998, and the recoveries were from 96.8 to 103.6%. The method was successfully applied to determine these bioactive components in the samples of Prunella vulgaris L. and its beverage. The results found that ursolic acid and betulinic acid were the two most dominant active compounds in Prunella vulgaris L., while caffeic acid, p-courmaric acid, rutin and quercetin were too little to be detected or not be present.References1. S.Y. Kim, S.H. Kim, H.Y. Shin, J.P. Lim, B.S. Chae, J.S. Park, S.G. Hong, M.S. Kim, D.G. Jo, W.H. Park, T.Y. Shin: Effects of Prunella vulgaris on mast cell-mediated allergic reaction and inflammatory cytokine production. Exp Biol Med 2007, 232 (7): 921-926.2. J. Zheng, J.G. He, B.P. Ji, Y. Li, X.F. Zhang: Antihyperglycemic activity of Prunella vulgaris L. in streptozotocin-induced diabetic mice. Asia Pac J Clin Nutr 2007, 16: 427-431.3. X.Y. Fang, M.M.S. Yu, W.H. Yuen, S.Y. Zee, R.C.C. Chang: Immune modulatory effects of Prunella vulgaris L. on monocytes/macrophages. Int J Mol Med 2005, 16 (6): 1109-1116.