Optimisation of an ultrasound-assisted extraction followed by RP-HPLC separation for the simultaneous determination of oleanolic acid, ursolic acid and oridonin content in Rabdosia rubescens.
BACKGROUND
Rabdosia rubescens is a commonly used herb in traditional Chinese medicine and contains diterpenoids, triterpenoids and various other compounds. Among these components, oridonin, oleanolic acid and ursolic acid have gained considerable interest concerning anti-cancer activities. However, there is no suitable currently available method for the simultaneous evaluation of these three bioactive compounds in R. rubescens.


OBJECTIVE
To develop an optimised ultrasound-assisted extraction (UAE) method and an efficient HPLC method for the simultaneous evaluation of the three bioactive compounds in R. rubescens.


METHODS
Various parameters that can potentially affect the UAE process were investigated and optimised. HPLC operating conditions were also optimised, and the chromatographic separation was performed on a C(18) -column with an acetonitrile-water gradient as the mobile phase.


RESULTS
Validation of the HPLC technique developed showed that the method has good linearity, sensitivity, precision and accuracy. The combined UAE-HPLC method was applied to quantitate the amount of oridonin, oleanolic acid and ursolic acid in the plant sample and exhibited good repeatability (RSD (%) < 3.9), reproducibility (RSD (%) < 5.9), stability (RE (%) < 1.4) and recovery (mean (%) > 92.4). Furthermore, the combined UAE-HPLC method was applied successfully to the extraction and determination of oridonin, oleanolic acid and ursolic acid content in samples obtained from different geographical regions, which is the first time that this comparison has been investigated.


CONCLUSIONS
The combined UAE-HPLC process is a fast, convenient and appropriate method for the quantitative analysis of these three compounds in R. rubescens.
Graduate Institute and Department of Pharmacology, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan.
Yu-Chiao
YC
Yang
Ming-Chi
MC
Wei
Ting-Chia
TC
Huang
D002138:Calibration; D005591:Chemical Fractionation / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D045786:Diterpenes, Kaurane / Q000032:analysis* / Q000302:isolation & purification; D037602:Isodon / Q000737:chemistry; D057230:Limit of Detection; D008516:Medicine, Chinese Traditional; D009828:Oleanolic Acid / Q000032:analysis* / Q000302:isolation & purification; D010946:Plants, Medicinal / Q000737:chemistry; D015203:Reproducibility of Results; D014315:Triterpenes / Q000032:analysis* / Q000302:isolation & purification; D014465:Ultrasonics; D000097245:Ursolic Acid
D045786:Diterpenes, Kaurane; D009828:Oleanolic Acid; D014315:Triterpenes; D000097245:Ursolic Acid; C011959:oridonin