Ultrasound-assisted extraction of bioactive compounds from a medicinal plant: Impact on phenolic content and antioxidant capacity

Ultrasound-assisted extraction (UAE) is increasingly regarded as a promising green technology, offering significant environmental and economic benefits, including lower energy consumption, shorter extraction time, and reduced solvent usage. These advantages make UAE a sustainable alternative to conventional extraction techniques, especially in the field of natural product research. In the present study, UAE was employed to extract phenolic compounds from Verbascum sinuatum leaves. Several solvents were used to compare their efficiency in extracting bioactive compounds. The total phenolic content (TPC) of each extract was measured using the Folin–Ciocalteu method, while antioxidant activity was evaluated through the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay. Among all tested solvents, 50% ethanol proved to be the most effective, yielding 105.97 ± 3.97 µg of gallic acid equivalents (GAEs) per mg of dry extract. This extract also demonstrated high antioxidant activity, with an IC50 value of 163.65 ± 0.08 µg/ml, indicating strong free radical scavenging potential. These results suggest that UAE, particularly with hydroalcoholic solvents such as 50% ethanol, is highly efficient for recovering phenolic compounds from plant matrices. These findings are consistent with literature data, highlighting the potential of UAE to produce high-quality antioxidant agents in a short time compared to conventional extraction methods. UAE typically reduces extraction time from several days or hours to tens of minutes compared to maceration, as reported for various Verbascum species.