| Extraction technology of isoflavones in Trifolium pratense was studied by single factor and orthogonal experiment. Effects of ethanol-water solvent, extraction temperature, extraction time, and ratio of liquid to material on extraction rate of isoflavone were investigated. The optimum extraction conditions for Trifolium pratense isoflavones were established as follows: 75% ethanol (V/V) as solvent, ratio of solvent to material 10:1(V/W), reflux extraction at 70℃for 1h for each time. They were all extracted twice. CH3CO2CH2CH3 also was used to purify the product gotten by the first step which was established as follows: the ratio of NaOH solvent which was used to slove the material was 4:1(V/W), the rate of reaction mixture solvent was 3% HCL(V/V), reflux extraction at 60℃for 1h for each time. It was found that AB-8 resin was an excellent adsorbent with high adsorption and desorption capacity among 4 types of macroporous resins selected for Trifolium pratense isoflavones. The effect of ethanol concentration, pH and flow rate of the infusion on the adsorption of AB-8 resin were also studied in dynamic adsorption experiment. The results showed that extract solution at a concentration of 0.8-4 mg/mL, pH of 8.5, flow rate of 2 BV/h as the optimal condition. When we use 4-6 BV 70-80% ethanol as eluent in 2 BV/h speed, desorption rate of isoflavones could reach up to over 90%. By using the HPLC , the solution which we collected has a purity about 50%.
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