Study on Optimization of Acid Extraction Process Based on Response Surface Methodology and Macroporous Resin Purification Process of Vitexin From <i>Odontosoria chinensis</i>

ABSTRACT Vitexin has various pharmacological activities, including cardiovascular and cerebrovascular protection, anti‐tumor effects, blood glucose lowering, blood pressure reduction, bacteriostasis, and anti‐inflammatory and analgesic properties. This study established an extraction and purification process for the rapid preparation of vitexin from Odontosoria chinensis . The content of vitexin in the extract of O. chinensis was determined by high‐performance liquid chromatography (HPLC). The extraction process of vitexin from O. chinensis was optimized by single‐factor combined with response surface methodology, taking the concentration of hydrochloric acid, extraction temperature, extraction time, ethanol concentration, and solid‐liquid ratio as the factors. The experimental data were fitted into a second‐order polynomial equation through multiple regression analysis and analysis of variance, and a mathematical model for the optimization experiment was established. The purification process of vitexin was optimized by D101 macroporous resin and preparative LC. The results showed that the optimal extraction process of vitexin was as follows: extraction temperature of 80°C, solid‐liquid ratio of 1:25, hydrochloric acid concentration of 2.5 mol/L, extraction time of 180 min, and ethanol concentration of 60%. Under these conditions, the extraction amount of vitexin was 4.07 mg/g, which was in good agreement with the predicted value of 4.15 mg/g by the model. The purification process was as follows: the volume ratio of D101 macroporous resin column to sample solution was 1:1, the elution gradient was 30% ethanol, and the elution volume was 14 Bed Volumes; the elution conditions of preparative LC were 40% methanol. Under these conditions, the purity of vitexin was ≥95%. This method has high extraction efficiency, a simple purification process, and high purity of vitexin, which is suitable for large‐scale industrial production.