Abstract
Salvia dumetorum Andrz. ex Besser is a promising non-pharmacopoeial plant species with traditional medicinal potential. This study aimed to determine the optimal microwave-assisted extraction (MAE) conditions for obtaining a polyphenol-rich ethanolic extract from the S. dumetorum leaves. Dried and powdered leaves were extracted using 40% ethanol with different power of microwaves varying from 200 to 800 W and time of extraction 2–8 min. The extract was filtered, concentrated, and evaluated for yield, identification of phenolic compounds using high-performance liquid chromatography (HPLC), total phenolic content (TPC), and total flavonoid content (TFC). Extraction yields ranged from 2.20% to 25.80% based on dry weight. TPC and TFC were determined using Folin–Ciocalteu and aluminum chloride colorimetric assays, respectively, and are expressed as mg GAE/g and mg RUE/g of dry extract. The antioxidant activity of the extracts was evaluated using the DPPH (2,2-diphenyl-1-picrylhydrazyl radical) assay. According to HPLC analysis, the main phenolic components of the extracts were rosmarinic acid (1.78–2.95 mg/mL), chlorogenic acid (0.31–0.54 mg/mL), caffeic acid (0.11–0.20 mg/mL), rutin (up to 0.47 mg/mL) and ferulic acid (0.13–0.33 mg/mL); traces of myricetin were found only in isolated samples. The optimum extraction conditions were found to be 400 W microwave power, 8 min extraction time, one MAE cycle, and a 1:30 g/mL solvent-to-material loading ratio; TPC and TFC were evaluated as 35.23 ± 0.50 mg GAE/g DW and 19.94 ± 0.14 mg RuE/g DW, respectively, indicating the highest yield of polyphenolic compounds, antioxidant potential inhibiting 96.68% ± 0.27 of DPPH radicals, and IC50 = 10.24 µg/mL. These findings highlight the efficiency of MAE in producing a bioactive ethanolic extract of S. dumetorum, which can be further explored for potential applications as a natural antioxidant in pharmaceutical or cosmetic formulations.