Comparative Study on Extracts from Traditional Medicinal Plants Echinacea purpurea (L.) Moench and Onopordum acanthium (L.): Antioxidant Activity In Vitro and Anxiolytic Effect In Vivo

<b>Background:</b><i>Echinacea purpurea</i> (L.) Moench (EP) and <i>Onopordum acanthium</i> (L.) (OA) are promising medicinal plants with diverse biological activities but there is no information on the effects of their combinations. To harness the therapeutic potential of both while minimizing the risk of adverse effects, we prepared two combinations (CE1 and CE2) of EP and OA in ratios 1:1 and 3:1, respectively. <b>Methods:</b> Oxygen radical absorbance capacity (ORAC), hydroxyl radical absorbance capacity (HORAC), and an electrochemical assay were used to determine the antioxidant activity of the extracts in vitro. The anxiolytic and immunomodulatory properties were studied in rats. Animals were subjected to acute cold stress and anxiety-like behavior was evaluated by the elevated plus maze (EPM) and social interaction test (SIT). Serum IFN-γ, TNF-α and IL-10 levels were measured by ELISA. <b>Results:</b> CE2 demonstrated the highest antioxidant activity (1841.7 μmolTE/g by ORAC, 277.2 GAE/g by HORAC, and 39.6 by electrochemical method). Moreover CE2 produced anxiolytic-like effects-significantly increasing the open arms entries ratio (OAER; <i>p</i> < 0.001), open arms time ratio (OATR; <i>p</i> < 0.01) in the EPM, and prolonging the social interaction time (<i>p</i> < 0.05) versus the stressed control. OA increased OAER (<i>p</i> < 0.01) and OATR (<i>p</i> < 0.001), while EP increased only OAER (<i>p</i> < 0.01). CE1 showed no significant behavioral consequences. CE2 significantly reduced IFN-γ (<i>p</i> < 0.05), and IL-10 levels were elevated in OA and CE2 groups (<i>p</i> < 0.01). No significant changes in TNF-α levels were observed across groups. <b>Conclusions:</b> These findings indicate that CE2 and OA attenuate anxiety-like behavior and modulate the immune response primarily by stimulating IL-10 production.