Modulation of Phenolic Profiles and Antioxidant Capacity by Culture Medium and Tissue Type in Echinacea purpurea and Echinacea pallida

This study aimed to compare the accumulation of secondary metabolites in root and stem tissues of Echinacea purpurea and Echinacea pallida grown in vitro on different basal media (MS, WPM, B5). Five major caffeic acid derivatives (CADs: caftaric, chlorogenic, caffeic, echinacoside, and cichoric acid), total phenolic content (TPC), total flavonoid content (TFC), and total antioxidant capacity (TAC) were measured. In E. pallida, the highest levels of caftaric acid (11.29 ± 0.06 mg/g DW) and cichoric acid (11.79 ± 0.01 mg/g DW) were found in root tissues on B5 medium, while echinacoside reached 8.29 ± 0.26 mg/g DW on WPM. Chlorogenic acid was most abundant in roots on MS (1.57 ± 0.06 mg/g DW). Caffeic acid was found in low amounts in WPM and B5 media only. In E. purpurea, cichoric acid reached the highest value overall in B5-grown root tissue (70.64 ± 0.41 mg/g DW). The same tissue also showed high caftaric (11.05 ± 0.03 68 mg/g DW) and caffeic acid (0.35 ± 0.0168 mg/g DW) levels. Chlorogenic acid peaked in WPM roots (5.25 ± 0.68 mg/g DW). Echinacoside was not detected in this species. Antioxidant parameters also differed significantly by species, tissue, and medium. In E. purpurea root tissues, the highest TPC (69.12 ± 1.98 mg GAE/g DW) and TFC (15.74 ± 0.93 mg QE/g DW) were found in B5 medium, while the highest TAC (%85.90) was recorded in WPM. E. pallida generally had lower antioxidant values. Overall, secondary metabolite accumulation was strongly influenced by species, tissue type, and medium. B5 was most effective for CADs, and WPM supported greater antioxidant capacity. E. purpurea outperformed E. pallida in both cichoric acid content and antioxidant potential, indicating its promising potential for targeted metabolite production in plant tissue culture.