Extraction-Driven Modulation of Bioactivity in Echinacea angustifolia: Phytochemical Profiling, Biological Activities, Molecular Docking, and DFT Insights

Abstract

Echinacea angustifolia, which is traditionally used for immune support and infection-related disorders, contains phenolic bioactive compounds. However, variation in phenolic recovery via extraction methods limits its standardization. This study compares ultrasound-assisted extraction (UAE), supercritical CO₂ (scCO₂), and Soxhlet extraction to determine the method that best enriches active constituents and elucidates their biological effects. Leaf extracts were prepared and analyzed for antimicrobial activity (agar diffusion and broth microdilution), antioxidant capacity (DPPH), and cytotoxicity assays against Caco-2 cells (MTT assay). High performance liquid chromatographic (HPLC) analysis revealed ellagic acid as the dominant phenolic compound, with UAE yielding the highest content (387 µg/mL; 19,3 µg/g), surpassing scCO₂ and Soxhlet extracts (81.4 and 81.6 µg/mL, respectively). Extract from UAE also exhibited the strongest biological performance, showing the highest inhibition against Bacillus subtilis (22.90 ± 0.10 mm), the lowest MIC against Staphylococcus aureus (7.8 µg/mL), the strongest antioxidant activity (DPPH IC₅₀ = 6.1 µg/mL), and the greatest cytotoxicity against Caco-2 cells (IC₅₀ = 76.38 ± 0.32 µg/mL). Docking studies showed favorable binding of ellagic acid (S = −6.578 kcal/mol), while DFT confirmed its structural stability and reactivity. This study links ellagic acid enrichment in the extract to bioactivity and computational analysis.