Ultrasound-Assisted Extraction of Bioactive Compounds from Acmella oleracea L. Leaves: Optimization by Response Surface Methodology and Comparison with Percolation

The extract of Acmella oleracea L. (jambu) contains significant amounts of spilanthol and phenolic compounds, which have wide-ranging applications in the cosmetic and pharmaceutical industries. The objective of this study was to optimize ultrasound-assisted extraction (UAE) of hydroethanolic extracts from A. oleracea L. using a Box–Behnken factorial design combined with response surface methodology and to directly compare the results with those of the conventional percolation method. The effects of the ethanol-to-water ratio, extraction time, and solid-to-solvent ratio were evaluated on yield, total phenolic content, total flavonoid content, and antioxidant activity. In addition, Fourier-transform infrared (FT-IR) spectroscopy was used for chemical characterization and extraction monitoring. For UAE, the optimal conditions established were an ethanol/water ratio of 47:53 (v/v), an extraction time of 13.2 min, and a solid-to-solvent ratio of 1:10 (m/v). In contrast, optimal percolation yielded an 11.03% recovery using a 70:30 (v/v) ethanol/water ratio. UAE provided a significantly higher yield (17.61%) and better recovery of bioactive compounds, as well as superior antioxidant activity in all assays. FT-IR analysis confirmed the preservation of functional groups, demonstrating that UAE optimizes the recovery of oxygen-containing compounds. It is concluded that UAE is a green, rapid, and sustainable alternative that maximizes the potential of A. oleracea L. for future cosmetic and nutritional formulations.