Optimization and modeling of ultrasound-assisted extraction of ursolic acid from selected medicinal plants

The current research focuses on optimizing extraction parameters for isolating Ursolic acid from Plectranthus amboinicus (Indian balm), Rosmarinus officinalis (Rosemary leaves), and Ocimum basilicum (Basil leaves), using both maceration, a conventional technique as well as ultrasound-assisted extraction. A one-factor-at-a-time approach was employed to optimize extraction parameters. Among the three plant sources analyzed, rosemary exhibited the highest crude yield and ursolic acid content, and HPLC analysis confirmed the presence of ursolic acid with 26.956 mg/L in rosemary, 16.374 mg/L in basil, and 0.359 mg/L in Indian balm. Thus, rosemary was selected for further modeling and optimization to provide a basis for future scale-up studies, and mathematical models were applied to describe the effects of individual parameters, all showing good agreement of R² > 0.96. RSM based optimization was further applied, which showed that ultrasonic power of 157.5 W at 45 °C for 40 min was the optimum condition with a maximum yield of 76.48%, with the model showing an R² of 0.9990 and statistical significance (p < 0.0001). The optimized UAE process showed remarkable extraction efficiency compared to conventional maceration. Thus, this study, combining experimental optimization of extraction parameters, mathematical modeling, and RSM for efficient extraction of ursolic acid, is an integrated approach.