Optimization of solvent sonication-maceration for enhancing total phenolic content and antioxidant activity of Portulaca oleracea L. extract using the simplex centroid design method

Abstract

The extraction of bioactive compounds from Portulaca oleracea L., a plant renowned for its diverse pharmacological effects, is significantly influenced by the choice of solvent. Therefore, this study aims to identify the optimal solvent or the combination of solvents for extracting P. oleracea using the simplex centroid design (SCD) method based on total phenolic content (TPC) and antioxidant capacity. The plant samples were extracted using a combination of sonication and maceration methods, and subjected to optimization using Design Expert 13.0. TPC was then quantified using the Folin-Ciocalteu method, while antioxidant capacity was assessed with the ferric-reducing antioxidant power (FRAP) method. The results showed that acetone-water was the solvent combination with the highest TPC, while acetone-water-methanol gave the highest antioxidant capacity. Based on a quadratic model with R² values of 0.9331 for TPC and 0.8074 for FRAP, the optimal solvent formulations were water (0.342), acetone (0.389), and ethanol (0.269), achieving a desirability level of 0.884. In addition, confirmation tests validated the results within the permissible interval (PI) values, indicating the reliability of the proposed model. Solvent combinations for P. oleracea extraction were successfully optimized through the application of SCD, yielding extract rich in phenolic content and antioxidant capacity. The results were expected to serve as a foundation for future investigations of P. oleracea and its pharmacological potential.