Studies On Extraction And Separation Of The Active Constituents In Chinese Traditional Medicine

The studies of traditional Chinese medicine involve the extraction, separation and characterization of the active constituents. The extraction plays an important part in traditional Chinese medicine research. At present,of the traditional extraction techniques of major drawbacks of is long extraction time, high solvent consumption.Therefore it is important to develop a fast and effective extraction method. The special features of microwave-assisted extraction and ultrasonica extraction technique over traditional extraction are short time, low temperature, low energy consumption and high extraction yield. Good experimental results obtained by microwave-assisted and ultrasonica extraction show that these extraction methods could be extensively applied to the extraction of active constituents from natural products.In the thesis, some extraction methods to extract the active constituents from traditional Chinese medicines were developed. There are dynamic ultrasonic extraction method, pressurized microwave-assisted extraction and atmospheric pressure microwave-assisted extraction.A dynamic ultrasonic extraction (DUE) coupled with on-line detection by spectrophotometry was proposed for the determination of total safflower yellow pigments (caculated against safflor yellow A) in Carthamus tinctorius L.and total flavonoids (calculated against scutellarin) in Scutellaria barbata D. Don.The extraction was performed in a common self-made extraction vessel placed inside an ultrasonic bath and a peristaltic pump was used to deliver the solvent. Several parameters of DUE, including flow rate of extraction solvent, ultrasonic power and sample amount and concentration of extraction solvent were optimized. Compared to the off-line method, the on-line approach has the advantages of minimum sample amount (5mg), on-line monitoring the extraction process and time-saving (10min, 12.5 min).Compared with offline method, the proposed method would be more convenient for obtaining continuous measurements and rapid optimization of the extraction process.Three microwave-assisted extraction (MAE) methods were studied, including pressurized microwave-assisted extraction, flow microwave-assisted extraction, atmospheric pressure microwave-assisted extraction.MAE process of extracting anthaqinones from Rhubarb were studied.The effects of solvent concentration,radiation time , solid/liquid ratio and microwave power were discussed in orthogonal experiments. The results show that the optimized extraction parameters were 70% ethanol,radiation time 2 min,solid/liquid ratio 1:30 and microwave pressure 300Kpa. the highest extraction yield is 2.86%.The experimental results indicated that the higher extraction yield can be obtained 1.97% by Microwave-assisted dynamic extraction (MADE) when extraction solvent is 70% ethanl,solvent uptake rate is 4 mL/min and irradiation power is 80%. MADE only needs 10 min.We investigated purification of two flavonoids from hydrolyzed products of Epimedium korenum Nakai extract by high-speed counter-current chomatography (HSCCC).Dried Epimedium korenum Nakai powder was extracted two times with 70% methanol (v/v), crude extract was dried by evaporator to dryness in vacuo. 2mol/L HCll was used to dissolve the sediment.This solution was heated for 22h. A two-phase solvent system consisting of hexane–ethylacetate–methanol–water (6:4:5:1, v/v/v/v), showed a baseline separation of icariside from other components in the hydrolysis mixture. Anhydroicaritin was separated from other components in the hydrolysis mixture by using a two-phase solvent system consisting of hexane- ethylacetate–acetonitrile (9:4:6, v/v/v). The structure of icariside and anhydroicaritin were identified by LC-ESI-MSn.