Application of Macroporous Resins in Separating Licorice Flavonoids and Glycyrrhizic Acid
- 化学化工－已发表论文 
本文在比较了四种大孔树脂对甘草酸和甘草总黄酮静态分离性能的基础上,筛选出大孔树脂XDA-1,对它的动态吸附分离条件如上样液浓度、洗脱溶剂及洗脱流速进行了进一步的研究。结果表明,树脂XDA-1对甘草总黄酮和甘草酸的吸附量大,易于洗脱,分离效果好,最终的黄酮收集液中不含甘草酸。本实验的优化条件为:上样液pH=5,甘草酸浓度为1.5 mg／mL,总黄酮浓度为0.75 mg／mL,上样流速为3 BV／h;洗脱液采用1.5 BV／h 45％的乙醇为最佳。再用含1％NaOH的80％乙醇以1.5 BV／h流速洗脱,得到甘草酸。总黄酮的收率为69.7％,甘草酸收率为52％,纯度为65.5％。Glycyrrhizic acid (GA) and licorice flavonoids (LF) are main bioactive components in licorice. However, long-term excessive intake of glycyrrhizic acid could cause side effect such as sodium retention and hypertension. In order to separate these components individually, and to produce licorice extracts aiming at different applications, a preparative scale separation technique is needed. Against this background, the sorption and desorption properties of licorice flavonoids (LF) and glycyrrhizic acid (GA) on macroporous resins including XDA-1, LSA-10, D101 and LSA-20 have been studied to gain better understandings on the separation characteristics of these resins. The adsorption capability of the resins is found to be strongly dependent on the pH value of the feed solution. Adsorption isotherms were obtained by batch experiments and the data are fitted to the Freundlich equation to evaluate the adsorption properties of these resins. XDA-1 is found to provide the best fit to the Freundlich isotherm. It has much higher adsorption capacity for GA and LF than other resins. XDA-1 shows a higher adsorption affinity towards LF than that of GA based on the calculated adsorption isotherms. Dynamic adsorption and desorption on the selected XDA-1 resin were carried out in a laboratory packed column (0. 5 cm×30 cm) to obtain optimal parameters for LC separation. A simple preparative separation procedure for LF and GA from licorice root was established. An LF enriched extract containing up to 60% LF but without GA contamination; and a GA extract with 65. 6% chromatographic purity have been prepared by the method.