Phytochemical Profile and Biological Activities of Inula helenium L. Extract: Antioxidant, Antimicrobial, Antiplatelet and Anticoagulant Evaluation

Background/Objectives: Inula helenium L. (Asteraceae) is widely used in traditional medicine, and its essential oil has demonstrated antimicrobial properties. The aim of this study was a comprehensive investigation of the chemical composition and biological activity of a concentrated extract of Inula helenium L. roots, including the determination of the main groups of biologically active substances and the assessment of antioxidant, antimicrobial, anti-aggregatory and anticoagulant properties. Methods: Inula helenium L. roots were extracted by UAE, the optimal conditions were double extraction with 70% ethanol at 30 kHz for 30 min. Chemical profiling was performed by HPLC-ESI-MS against 20 reference phenolic compounds, with method validation. Antimicrobial activity was assessed by microdilution against Gram-positive, Gram-negative and fungal strains (MBC/MFC). Antioxidant activity was evaluated in two chemiluminescence model systems simulating reactive oxygen species generation and lipid peroxidation. Anti-aggregatory and anticoagulant effects were studied in vitro on platelet-rich and platelet-poor plasma. Results: 11 polyphenolic compounds were identified and quantified, including five phenolic acids (gallic, chlorogenic, caffeic, ferulic and p-coumaric acids) and six flavonoids (hyperoside, naringenin, quercetin, kaempferol, luteolin and apigenin). The extract exhibited antimicrobial activity with MBC values of 3.91–62.5 μg/mL against Gram-positive bacteria, 2.5–10 μg/mL against Gram-negative bacteria, and 10 μg/mL against Candida albicans. The extract moderately inhibited platelet aggregation, prolonged aPTT, and reduced chemiluminescence by 15–20% relative to the control. Conclusions: The thick extract of Inula helenium L. roots contains bioactive phenolic compounds and exhibits moderate antimicrobial, antioxidant and anticoagulant activity, supporting its potential as a natural multifunctional agent and justifying further in vivo studies and dosage form development.