Choline chloride-based natural deep eutectic solvents for microwave-assisted extraction of phenolic compounds from Satureja montana L. (Lamiaceae)

Owing to their phenolic compound content, Satureja montana L. (Lamiaceae) extracts have been reported to exhibit antioxidant activity. An innovative extraction approach combines green extraction techniques with natural deep eutectic solvents (NADES) to obtain extracts with enhanced biological potential while reducing energy consumption, extraction time, and environmental impact. Accordingly, this study aimed to evaluate and compare the efficiency of choline chloride-based NADES and conventional solvents in the microwave-assisted extraction (MAE) of S. montana herb, by assessing the preliminary chemical composition and antioxidant potential of the obtained extracts. MAE was carried out at 180 W for a total of 15 s, using choline chloride:glycerol NADES, choline chloride:sorbitol NADES, 70% ethanol, and water. In the obtained extracts, total phenolic content (TPC) and total flavonoid content (TFC) were determined spectrophotometrically. The antioxidant potential was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging test and the cupric reducing antioxidant capacity (CUPRAC) assay. A higher TPC was observed in both choline chloride-based NADES extracts, whereas the highest TFC content was determined in the 70% ethanol extract. According to the DPPH and CUPRAC assays, the extract obtained using choline chloride:glycerol NADES exhibited the strongest antioxidant potential. These results indicate that the combination of green extraction techniques and NADES may represent a sustainable approach for obtaining S. montana extracts, supporting their further investigation and potential application in nutraceutical or pharmaceutical formulations.

Acknowledgments: This work was supported by the Provincial Secretariat for Higher Education and Scientific Research, Province of Vojvodina (Grant No. 003874431 2025 09418 003 000 000 001).