Response surface methodology-based optimization ultrasound-assisted extraction of Melastoma malabathricum leaves for phenolic; flavonoid contents and antioxidant activity

M. malabathricumis traditionally used to treat dysentery,diarrhea, hemorrhoids, gastric ulcers, high blood pressure, and diabetes. Ultrasound-Assisted Extraction (UAE) is a modern extraction technique that has seen significant growth in recent years, as it is consideredan environmentally friendly method and aligns with the principles of green chemistry. To support extraction optimization, the Response Surface Methodology (RSM) with Box–BehnkenDesign (BBD) was employed in this study, as it was used to optimize the extraction of phytochemical content (Total Phenolic Content-TPC and Total Flavonoid Content-TFC), as well as antioxidant activities (2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)-ABTS andFerric Reducing Antioxidant Power-FRAP) as response variables. The extraction optimization process is emphasized on three variables, namely sample-to-liquid ratio(A) 1:10–1:50, extraction time (B) 10–60 minutes,and solvent concentration (C) 50-96%. The optimization results are as follows: A is 1:50, B is 10 minutes, C is 96%, andthe desirability value is 0.898. Variable response to TPC content was 339.006±19.812 mgGAEg; TFC of 17.717±0.336 mgQEg; freeradical scavenger activity (ABTS = 0.120±0.050 μg/mL), and ferric reduction power (FRAP = 0.741±0.172 μg/mL)—the impact of process variables onM.malabathricumextraction is A and C variables increase TPC, TFC, and FRAP responses; the B variable correlates with the optimum time, as short extraction times.Overall, the experimental results were close to the model predictions for TPC, TFC, and FRAP. These findings demonstrate the potential of RSM-BBD for identifying optimal UAE conditions for extractingM. malabathricumleaves.