Determination of Kaurenoic Acid in Acanthopanax trifoliatus by Ultra-High Performance Liquid Chromatography Coupled with Tandem Mass Spectrometry (UHPLC-MS/MS)

Acanthopanax trifoliatus (L.) Merr. (A. trifoliatus) belongs to the family Araliaceae, which is called "Le Cai", and is an indigenous plant to Guangdong Province that has been prevalently planted for years. A. trifoliatus is used in folk medicine and has ginseng-like activity. Kaurenoic acid ((-)-kaur-16-en-19-oic acid, KA) is a kaurane-type diterpenoid that is regarded as a major compound in A. trifoliatus. Early studies have reported the determination of KA by HPLC capillary electrophoresis. However, KA could not be completely separated from other components in the plant extract by HPLC because of their similar molecular structures and physical and chemical properties. UHPLC-MS/MS could be a useful tool to identify and quantify KA. In the present work, a UHPLC-ESI-MS/MS method for determining KA in A. trifoliatus was developed and validated. KA was extracted from lyophilized A. trifoliatus leaves by ultrasound-assisted extraction and further purified by solid phase extraction (SPE). KA was quantified and separated on an Accucore C-18 LC column. Mass spectrometry with multi-reaction monitoring (MRM) and quantitative fragment ion/product ion (m/z: 301.3/301.3) in ESI negative mode was used for quantification. The intra-assay and inter-assay relative standard deviation (R.S.D.) were 2.8% and 3.2%, respectively. The inter-person R.S.D. on the same day was 3.6%. The inter-instrument R.S.D. with the same model on the same day was 2.9%. The recoveries evaluated upon spiking three different concentrations of KA were above 97%. A minor matrix effect of 94% was observed. This method has been applied successfully for the determination of KA in A. trifoliatus leaves.