Vitexin and iso-vitexin, potential bioactive compounds for nutraceutical or pharmaceutical applications, are natural phenolic compounds present in mung bean seed coats. These compounds could be extracted using ethanol-based solvent. Improving the purity of vitexin and iso-vitexin in the crude extract is important for efficient use. This work proposed a continuous system for the separation of vitexin and iso-vitexin based on isocratic liquid chromatography. The adsorption characteristics of individual compound was investigated via pulse injection and breakthrough experiments. The appropriate mobile phase was 18–82–2.5%v/v ethanol–water–acetic acid based on selectivity and resolution of the separation, toxicity of mobile phase, and pressure drop in the system using SUPELCOSIL LC-18 column as stationary phase. The adsorption parameters verified by adsorption–desorption experiments of a binary mixture of vitexin and iso-vitexin were used for designing a three-zone simulated moving bed (SMB) system for the separation both compounds. Finally, a response surface methodology (RSM) was used to optimize the operating conditions of the SMB. At the optimal conditions (maximized productivity was 0.3417 mg/L min), the switching time was 16 min and the flowrate ratio in sections I, II and III was 3.400, 2.920, and 3.150, respectively. The purity of vitexin and iso-vitexin was 98.46% and 98.44%, respectively.

Graphic Abstract

中文翻译：

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使用三区模拟移动床 (SMB) 从绿豆种皮中分离牡荆素和异牡荆素

牡荆素和异牡荆素是用于保健品或药物应用的潜在生物活性化合物，是存在于绿豆种皮中的天然酚类化合物。这些化合物可以使用乙醇溶剂提取。提高粗提取物中牡荆素和异牡荆素的纯度对于有效使用很重要。这项工作提出了一种基于等度液相色谱分离牡荆素和异牡荆素的连续系统。通过脉冲注入和突破实验研究了单个化合物的吸附特性。根据分离的选择性和分辨率、流动相的毒性以及使用 SUPELCOSIL LC-18 柱作为固定相的系统压降，合适的流动相是 18-82-2.5%v/v 乙醇-水-乙酸。通过牡荆素和异牡荆素的二元混合物的吸附-解吸实验验证的吸附参数用于设计用于分离两种化合物的三区模拟移动床 (SMB) 系统。最后，响应面方法 (RSM) 用于优化 SMB 的操作条件。在最佳条件下（最大生产率为 0.3417 mg/L min），切换时间为 16 min，I、II 和 III 段的流量比分别为 3.400、2.920 和 3.150。牡荆素和异牡荆素的纯度分别为98.46%和98.44%。响应面方法 (RSM) 用于优化 SMB 的操作条件。在最佳条件下（最大生产率为 0.3417 mg/L min），切换时间为 16 min，I、II 和 III 段的流量比分别为 3.400、2.920 和 3.150。牡荆素和异牡荆素的纯度分别为98.46%和98.44%。响应面方法 (RSM) 用于优化 SMB 的操作条件。在最佳条件下（最大生产率为 0.3417 mg/L min），切换时间为 16 min，I、II 和 III 段的流量比分别为 3.400、2.920 和 3.150。牡荆素和异牡荆素的纯度分别为98.46%和98.44%。

图形摘要