| Total of alfalfa saponins (TAS) is an important component in medic plant, which may be biologically active in reducing plasma cholesterol and guarding against atherosclerosis. There is no systemic report on the research of extraction and purification technique of TAS in China. The objective of this paper is to lay a foundation for compositive utilization and exploitation of alfalfa plant.On the bases of previous research of TAS and the facilities of the laboratory, this thesis systematically studied a colorimetric method for quantitative analysis of TAS, optimized the parameters of ultrasonic extraction using uniform design and the parameters of water and ethanol reflux extraction which was screened by orthogonal design. The purification processes of TAS with macroporous resin was generally studied by taking adsorption quantities, eluting ratio and purify of total saponins as indices. The major results are shown as follows:The content of TAS was determined by UV-VIS spectrophotometry after it has been colored. Using oleanolic acid as a standard substance, assured detective wavelength of TAS was 545 nm and standard curve equation was Y=-0.0294+0.0485X, the average recovery was 98.96% with RSD of 2.71%. The method is rapid, accurate and repeatable.Different methods of extracting on total saponins from alfalfa were studied. (1) Aqueous extraction. Single element test and L9 (34) orthogonal design test were performed about extraction temperature, time, frequency and the solid liquid ratio . The result shows that the average extraction rate of TAS is 0.92% at 70℃, for 1.5h, twice and solid liquid ratio of 1:30. (2) Ethanol solution extraction. The result shows that technological parameter of extraction rates of TAS is the higherst when soaking solutions contain 70% ethanol, at 80℃, for 2.0h, with the solid liquid ratio of 1:20. The average extracting rate of TAS is 1.56%. (3) Ultrasonic extraction. The effects of ultrasonic frequency, ratio of solid to liquid, concentration of ethanol, ultrasonic time were studied with U8(84) uniform design. Ultrasonic frequency and solid liquid ratio have a significant effect (a=0.01) on the extraction rate of TAS. While concentration of ethanol and ultrasonic time have a less significant effect ( |
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