From Traditional Infusion to Antioxidant Potential: Comparative Evaluation of Water, Methanol, and Acetone Extracts of Sideritis akmanii

Herbal teas are widely consumed worldwide and represent an important component of the traditional diet in Türkiye. Sideritis akmanii, an endemic species used locally as a herbal infusion, has been scarcely characterized in terms of its phenolic composition and antioxidant properties. This study comparatively evaluated water, methanol and acetone extracts of S. akmanii prepared to mimic traditional use (water) and laboratory solvent extraction (methanol, acetone). Total phenolic content (TPC) was determined by the Folin–Ciocalteu method, antioxidant capacity (AC) by the phosphomolybdenum assay, and radical-scavenging activity by the DPPH test at 25, 50 and 100 ppm. Methanol yielded the highest TPC (41.31 ± 3.65 mg GAE/g), followed by acetone (32.41 ± 2.48 mg GAE/g) and water (28.81 ± 2.27 mg GAE/g), and showed the greatest AC (123.76 ± 4.58 μmol AAE/g for methanol vs. 97.14 ± 5.68 and 67.69 ± 2.17 μmol AAE/g for acetone and water, respectively). DPPH inhibition increased in a dose-dependent manner for all extracts, with methanol achieving up to 31.87 ± 2.86% inhibition at 100 ppm, acetone 24.54 ± 3.88%, and water 14.02 ± 1.27%. Radar plots and Pearson correlation analysis revealed uniformly strong positive associations among TPC, AC and DPPH responses (r = 0.90–1.00), while linear regression confirmed TPC as a major predictor of AC (R² = 0.929). Overall, the findings indicate that S. akmanii is a promising natural source of antioxidants, with methanol extracts showing the highest in vitro activity, and support further phytochemical and pharmacological investigation of this endemic species.