Separation of Vitexin and Iso-vitexin from Mung Bean Seed Coats Using a Three-Zone Simulated Moving Bed (SMB)

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.