Rapid determination of cinnamic acid and harpagoside in a traditional Chinese medicine of Scrophularia ningpoensis by microwave-assisted extraction followed by high performance liquid chromatography (HPLC)

Cinnamic acid and harpagoside are important active components present in Scrophularia ningpoensis, which has been used in the treatment of several diseases such as pharyngalgia. In the present study, a novel method based on high performance liquid chromatography (HPLC) following microwave-assisted extraction (MAE) was developed for the determination of cinnamic acid and harpagoside in a traditional Chinese medicine (TCM) of S. ningpoensis. Effective chromatographic separation was achieved on a C18 column at the detection wavelength of 278 nm. Microwave power of 400 W and irradiation time of 4 min were found to be the optimum conditions for the MAE process. In addition, to demonstrate the feasibility of the MAE-HPLC method, the conventional ultrasound extraction (USE) method was used for the analysis of cinnamic acid and harpagoside in the TCM. The results indicated that MAE-HPLC is a simple, rapid, efficient, and low cost method for the determination of cinnamic acid and harpagoside in TCM as well as a potential tool for the assessment of TCM quality.   Key words: Scrophularia ningpoensis, Cinnamic acid, harpagoside, microwave-assisted extraction, liquid chromatography, traditional Chinese medicine.