Comparative Study of Elsholtzia ciliata (Thunb.) Hyl. and Elsholtzia stauntonii Benth. Antioxidant Capacity

Abstract

Elsholtzia ciliata (Thunb.) Hyl. and E. stauntonii Benth. are aromatic plants valued for their biologically active compounds. This study assessed their antioxidant potential by determining total polyphenols (TPC), flavonoids (TFC), phenolic acids (TPAC), and antioxidant activity using the DPPH, FRAP, and ABTS assays. Plant material was collected from the experimental fields of the Institute of Climate Smart Agriculture in 2023–2024. E. stauntonii extracts contained significantly higher levels of phenolic compounds (TPC up to 69.67 mg GAE·g⁻¹, TFC up to 41.25 mg QE·g⁻¹, TPAC up to 19.26 mg CAE·g⁻¹) compared with E. ciliata (TPC up to 16.83 mg GAE·g⁻¹, TFC up to 10.35 mg QE·g⁻¹, TPAC up to 4.84 mg CAE·g⁻¹). Antioxidant activity was also stronger in E. stauntonii (FRAP up to 337.97 µmol·ml⁻¹) than in E. ciliata (FRAP up to 118.17 µmol·ml⁻¹). Correlation analysis revealed strong positive relationships between phenolic content and antioxidant activity in both species (r = 0.77–0.99). These findings highlight E. stauntonii as a particularly rich source of phenolic compounds with strong antioxidant potential, supporting its value for future biochemical and pharmacological applications.