Ultrasound-assisted extraction optimization of red betel leaf (Piper crocatum Ruiz & Pav) and characterization of the bioactive profile

Ultrasound-assisted extraction (UAE) of phytochemicals from Piper crocatum Ruiz & Pav leaves was optimized by response surface methodology (RSM) with a Box–Behnken design. The extraction time (X1, 10–30 min), ethanol concentration (X2, 60%–90% v/v), and temperature (X3, 40–75 °C) were investigated as independent variables. The optimized predictions for time, ethanol, and temperature were 17.68 min, 73.35%, and 57.62 °C, respectively. Under these conditions, the predicted values for total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (AA) were 17.64 mg GAE/g, 14.95 mg QE/g, and 41.23%, respectively. The models showed good fitness with R² values of 0.936–0.963 and non-significant lack-of-fit (p > 0.05). The experimental results were consistent with the model predictions. LC-HRMS and GC–MS analyses produced provisional annotations of various bioactive compounds, providing chemical insights into the observed bioactivity. Future development should include the evaluation of biological activity and scale-up to support practical industrial applications.