Optimization of ultrasonically extracted β‐sitosterol from <i>Berberis jaeschkeana</i> using response surface methodology

<i>Berberis</i> genus is recognized as a significant source of β-sitosterol and polyphenols. The inclusion of β-sitosterol into various health-related formulations has widened its potential in the pharmaceutical and nutraceutical industries. Process optimization ensures the maximum efficiency, consistency, and yield. In the current study, we employed mutual interaction effect to extract the β-sitosterol from the root bark of <i>Berberis jaeschkeana</i> using ultrasonic-assisted extraction (UAE) technique. In order to identify the optimal extraction parameters, we conducted a series of 29 experiments, varying factors, such as amplitude level, solid-to-liquid ratio, extraction time, and temperature. The mutual interaction effect encompasses several key components, including the Box-Behnken design, assessment of model fitness, coefficient of determination, analysis of variance (ANOVA), and the creation of three-dimensional (3D) response curves of response surface methodology (RSM). The outcomes of the analysis revealed notable model fitness, highlighting the presence of linear, quadratic, and interactive effects among the various factors examined. The optimized UAE conditions (amplitude level of 30%, time of 10 min, solid-to-liquid ratio of 20, and temperature at 50°C) were applied. Under the most favorable extraction conditions, the β-sitosterol was identified and quantified from <i>Berberis jaeschkeana</i> using high-performance liquid chromatography (HPLC). The β-sitosterol yield was measured at 43.52 mg per gram of the sample. Conclusively, the optimization approach for UAE using the mutual interaction effect contributes to a more rapid extraction process, resulting in a higher yield of β-sitosterol. Furthermore, this study design could be extended to other valuable species or compounds to efficiently extract nutraceutical compounds and enhance the sustainable utilization of natural products.