Study On Fast Extraction Of Active Compounds From Traditional Chinese Medicine

In the thesis, extraction methods for extracting active constituents from traditional Chinese medicines were developed. Microwave-assisted extraction (including dynamic microwave-assisted extraction), dynamic ultrasonic-assisted extraction and matrix solid-phase dispersion were studied. The target compounds were determined by high performance liquid chromatography (HPLC).Three microwave-assisted extraction (MAE) methods including atmospheric pressure microwave-assisted extraction (AMAE), pressurized microwave-assisted extraction (PMAE) and dynamic microwave resonant cavity extraction (dynamic microwave-assisted extraction, DMAE) were applied for extracting of ginsenosides from Panax ginseng C. A. Mey. Compared with ultrasonic-assisted extraction and a reference extraction method used in the Chinese pharmacopoeia, MAE provided higher extraction yields within a shorter extraction time. PMAE obtained the highest extraction yields of the five extraction methods. Moreover, the PMAE system has the advantage of extracting several samples in one extraction procedure which can improve the extraction efficiency. The DMAE system is easy to develop for on-line analysis and has the ability of real-time monitoring in the sample extraction process. In the second part seven kinds of ginsenosides in different parts (including main-roots, root-hairs, rhizomes, leaves and stems) of Panax quinguolium L. (P. quinquolium) were extracted by PMAE, and then the extracts were separated and determined by reversed-phase high performance liquid chromatography (HPLC) with ultraviolet detection (UV). It was found that the ginsenosides contents in different parts are very different. The experimental results show that on a dry weight basis, total contents of the seven ginsenosides in the leaves are the highest, followed by those in root-hairs, rhizomes, main-roots and stems. The total contents of the seven ginsenosides in roots, root-hairs and rhizomes increase with age of the plant (1 to 4-year-old) but decrease in leaves and stems. In all, studies on the variation of ginsenosides contents in different growth periods and parts of P. quinquolium are very important for comprehensive and expanding utilization of P. quinquolium, and for the proper artificial cultivation and production of P. quinquolium.A dynamic ultrasonic-assisted extraction (DUAE) system coupled with HPLC was used for the extraction of flavonoids from Epimedium Koreamum Nakai. The extractant was pumped by a peristaltic pump. The parameters which influence the extraction efficiency such as the concentration and flow-rate of the extractant, the extraction temperature, exposure time to ultrasonic energy, and the amount of sample, were investigated and optimized. The optimized conditions for DUAE were as follows: the extractant was 50% aqueous ethanol; the extractant flow-rate was 1.5 mL min-1; the extraction temperature was 50℃; the extraction time was 8 min; and the amount of sample was 15 mg. The proposed method was compared to static UAE provided in the Chinese pharmacopoeia and similar extraction yields were obtained. The main advantages of the proposed method are simple and rapid. Since ultrasonic extraction can be carried out without heating procedure, the thermal damage can be avoided which especially fit for extracting some thermal-unstable compounds.A method based on matrix solid-phase dispersion (MSPD) was developed for extraction of oleanolic acid (OA) and ursolic acid (UA) in Dashanzha Pills. The quantitative analysis of the two constitutes was determined by HPLC/UV. Octadecylsilyl (ODS)-derivatized silica (C18) and diatomaceous earth were used as matrix dispersion sorbents, separately. Four milliliters of water and 5mL of 70% aqueous methanol were used in the wash step, and 6 mL of methanol was used in the elution step. The ratio 0.1 g of sorbent versus 0.1 g of sample provides a complete retention for UA and OA in the extraction and wash step. Compared with the conventional method ruled in Chinese pharmacopoeia, the two extraction methods show satisfactory agreement with a significant decrease in sample preparation time and in solvent consumption of the proposed method. In general, the results from the described experiment indicate that MSPD is a good option for the extraction of oleanolic acid and ursolic acid in Dashanzha Pills.