Optimal Extraction Solvent for Purslane (Portulaca grandiflora Hook.) Flowers: a Study on Phenolic and Flavonoid Contents and Antioxidant Activities Using Microwave-Assisted Extraction

Purslane (Portulaca grandiflora Hook.) has the potential to act as an antioxidant due to the presence of secondary metabolites, such as phenolic compounds and flavonoids, which are abundant in its flowers. The efficiency of extracting these compounds can be influenced by the choice of extraction solvent. This study aimed to identify the optimal solvent for extracting purslane flowers using microwave-assisted extraction, evaluating total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities (DPPH and FRAP methods). The optimal solvent, determined using the simplex-centroid design (SCD) method and Design Expert software®, is a mixture of 41% acetone and 59% methanol. The results obtained were consistent with predicted values from verification tests, yielding a TPC of 3.599 mg GAE/g fresh weight, TFC of 1.796 mg QE/g fresh weight, and antioxidant activities of 0.669 µmol TE/g fresh weight (DPPH) and 9.231 µmol TE/g fresh weight (FRAP), with a desirability value of 0.712. The SCD method effectively optimized the extraction solvent for purslane flowers concerning TPC, TFC, and antioxidant activity.