基于解离度控制的桑枝生物碱树脂分离工艺优化

Optimization the purification progress on mulberry alkaloids based on the dissociation constants

关键词:  桑枝生物碱  1-脱氧野尻霉素  阳离子交换树脂  解离常数  吸附选择性

Key words:  mulberry alkaloids  1-deoxynojirimycin  cation exchange resin  dissociation constant  selective adsorption

摘要:

[目的] 基于生物碱解离常数（pKa）与氨基酸等电点（pI）的差异，筛选树脂处理的活化剂种类，优化桑枝生物碱分离纯化工艺。[方法] 分别采用常规的盐酸及不同pH值的缓冲液为活化剂对732阳离子树脂进行处理，柱前衍生化-高效液相色谱（HPLC）法对生物碱及氨基酸进行分析，比较桑枝水提液经吸附交换后的生物碱与氨基酸泄漏曲线，测定1-脱氧野尻霉素（DNJ）吸附量，考察氨水洗脱后产物中生物碱的色谱纯度。[结果] 常规的盐酸活化剂处理树脂，生物碱及总氨基酸均未泄漏，而采用pH5.6及4.6的缓冲液作为活化剂，总氨基酸提前泄漏；与pH5.6缓冲液相比，pH降至4.6时，生物碱吸附量由1.84mg/g（DNJ质量/树脂质量）提高至2.23mg/g；缓冲液处理后的生物碱提取物，色谱纯度由23.6%提高至79.6%。[结论] 通过调节树脂的pH值环境，可使生物碱和氨基酸以不同的解离状态存在，减少氨基酸吸附，提高阳离子树脂吸附选择性，提高生物碱分离纯化效果。

Abstract:

[Objective] To select optimum regenerating agent of ion-exchange resin and optimize purification of mulberry alkaloids based on the pKa of the alkaloids and the pI of amino acids. [Methods] The 732 resins were regenerated with hydrochloric acid and different pH buffer solution, respectively. The productions were determined by RP-HPLC with pre-column derivatization. This article calculated the leakage amount of alkaloids and amino acids the adsorbing amount. Meanwhile it also determined the peak ratio of alkaloids in products. [Results] Ultimately, the total amino acids leaked in a short time with the buffer solution at pH 4.6 as regenerating agent. However, both of the alkaloids and amino acids didn't leak with hydrochloric acid as regenerating agent. The adsorption amount was increased from 1.84 to 2.23 mg/g with the buffer solution at pH 4.6 compared to pH 5.6. The relative peak ratio of the alkaloids in productions is 79.6% with the buffer solution at pH 5.6 as regenerating agent, and 23.6% with hydrochloric acid as regenerating agent. [Conclusion] Through adjusting the pH of resin separation and controlling the dissociation degree of the alkaloids and the amino acids, the purity of the production was improved with decreased adsorption of amino acids and increased selectivity of the resin.