Optimizing Conditions for Ultrasound-Assisted Extraction of the Betulinic Acid, Oleanolic Acid, and Ursolic Acid from the Jujube using Response Surface Methodology (RSM)

Pentacyclic triterpenic acids have potential effects in treating human diseases. Thus, it seems necessary to have an effective method to extract and separate triterpenic acids from plants and fruits such as jujube. To this end, this study optimized ultrasound-assisted extraction of Betulinic acid (BA), Oleanolic acid (OA), and Ursolic acid (UA) from Iranian jujube using response surface methodology (RSM) and quantified by high-performance liquid chromatography (HPLC). Box-Behnken Design (BBD) was used to model the response surface. The selected independent variables were ultrasonic bath temperature (T), sonication time (theta), and liquid to solid ratio (alpha). The P-value and R-squared (R2) for all extraction efficiencies indicated a good correlation between the experimental results and those predicted by the quadratic model. The analysis of variance (ANOVA) results showed the significant impact of linear coefficients (T, theta, alpha), quadratic coefficients (T2, theta 2, alpha 2), and interaction coefficients (T theta, T alpha, theta alpha) of the model on the extraction of three triterpenic acids. The predicted optimal temperature, sonication time, and liquid to solid ratio were 40.34 degrees C, 34.63 min, and 14.85 mL/g. The maximum yields for BA, OA, and UA were 304.14, 170.61, and 195.23 mu g/g, respectively. Extraction was carried out by the calculated rounded up optimal values of T=40 degrees C, theta=35 min, and alpha=15 mL/g. The extraction efficiencies for BA, OA, and UA were 303.83 +/- 0.85, 169.52 +/- 0.86, and 195.84 +/- 0.75 mu g/g, respectively. These results were comparable to those calculated under model-optimized conditions, indicating the accuracy of our model.