Extraction Of Medical Ingredients From Angelica Sinensis And Ligusticum Chuanxiong With Supercritical CO₂

Traditional Chinese medicine (TCM ) is a scientific summary of rich experiences of the Chinese nation's struggle against disease for thousands of years. With occurring the upsurge of savageness, nutrition and returning natural all over the world, the catchword of"modernization and internationalization of traditional Chinese medicine"has become a very stringent strategy and action in China. Supercritical fluid extraction (SFE) is presently considered as one of the most clean and highly effective technologies for processing TCM. This thesis mainly explores the feasibility of extracting volatile oil, and some active components, such as ferulic acid and tetramethylpyrazine, from the herb of Angelica sinensis, Ligusticum Chuanxiong and their mixtures with supercritical CO₂.The influences of temperature, pressure and particle size on the yield of volatile oil extracted from the herb of Angelica sinensis were firstly studied. The experimental results show that, 2.6-4.06% oil can be obtained in the temperature ranges from 45 to 65℃and pressures from 30 to 50MPa. In order to enhance the solvent power of CO₂ for increasing the content of the ferulic acid in the extracts, three kinds of co-solvents were employed, and the dosage together with the adding methods for the co-solvent were also investigated. The experimental results indicate that the content of ferulic acid in the extracts can attain 1.277% under the investigated optimal conditions. In addition,81 components in volatile oil were identified by CG-MS,in which 61 components have not been reported in the references. Furthermore, 88 components were also identified in the extracts obtained with SC-CO₂ in presence of co-solvent, in which 26 components have not been identified in volatile oil.Extraction of volatile oil from Ligusticum Chuanxiong was studied in the second section. The experimental results show that 3.7-5.1% extracts can be obtained in temperature ranges from 45 to 65℃and pressures form 30 to 50MPa. When the content of ferulic acid in the extracts was considered as quality control index, different co-solvents were investigated in the similar ways as for extraction from Angelica sinensis. The extracts with the 8.24% yield, in which the content of ferulic acid was 0.735%, can be obtained under the investigated optimal conditions. In addition,74 components in volatile oil were identified by CG-MS,in which only 22 components have been reported in the references. 86 components were also identified in the extracts obtained with SC-CO₂ in presence of co-solvent, in which 28 components have not been identified in volatile oil.Extraction of volatile oil and active components such as ferulic acid and tetramethylpyrazine from the mixture of Angelica sinensis and Ligusticum Chuanxiong were also investigated. And the influence factors of extraction temperature, extraction pressure, particle size and co-solvents were further studied. The extracts with 7.12% yield, in which the content of ferulic acid was 0.832%, can be obtained under the optimal conditions.The solubilities of ferulic acid and tetramethylpyrazine in supercritical CO₂ were separately determined in the temperature ranging from 35 to 65℃and pressures form 00 to 35MPa. The experimental results show that the solubilities of ferulic acid in supercritical CO₂ are between 6.936×10-7 and 26.527×10-7 (mole fraction), while the solubilities of tetramethylpyrazine in supercritical CO₂ are 0.010-0.131 (mole fraction). The solubility data of ferulic acid and tetramethylpyrazine in supercritical CO₂ were correlated by Chrastil equation, with the values of AARD of 7.64% and 4.27%, respectively. Additionally, the solubility data of ferulic acid and tetramethylpyrazine were also calculated with P-R EOS.The solubility of volatile oil extracted from Ligusticum Chuanxiong in SC-CO₂ were estimated based the experimental data of SFE. Chrastil equation was employed to correlate the above solubility data with AARD of 5.94%. An improved version presented by the author was further used to correlate the solubility data with AARD value of 3.33%. The correlation results show that the improved version is better than Chrastil equation. The improved version was also tested by the solubility data from references.