Antioxidant activity of the extract fractions from leaves, stems, roots and flowers of Cirsium pendulum Fisch. was investigated. The results showed the greatest antioxidant activities in leaves by Rancimat, TBA and DPPH methods. Extracts of common thistle plants dose-dependently increased DPPH free radical scavenging activity, The extract from flowers and its hexane fraction showed the strongest antioxidant activity. HPLC analysis showed that BuOH fraction of the leaves had the highest amount of antioxidant chlorogenic and p-coumaric acids at 5.38 and 9.71 mg 100 g-1, respectively. It implies that common thistle plants had potent antioxidant activity, and their activities were differently exhibited depending on plant part and solvent fraction.

Common thistle contains water-soluble substances that are phytotoxic to neighboring plant species. A series of aqueous extracts from leaves, stems, roots and flowers of common thistle (Cirsium pendulum Fisch.) were assayed against alfalfa (Medicago sativa) seedlings to determine their allelopathy, and the results showed highest inhibition in the extracts from flowers and leaves, and followed by stems, and roots. The extracts at 40 g dry tissue L-1(g~;L-1) applied on filter paper in a Petri-dish significantly inhibited root growth of test plant by 87%. Methanol extracts at 100 g L-1 from leaves inhibited root growth of alfalfa and barnyardgrass (Echinochloa crus-galli) by 89 and 98%, respectively. Hexane and ethylacetate fractions of common thistle reduced alfalfa root growth more than did butanol and water fractions. Incorporation into soil with the leaf residues at 100g~;kg-1 inhibited shoot fresh weights of barnyardgrass and eclipta (Eclipta prostrate) by 88 and 58%, respectively, showing higher sensitivity in grass species. These results suggest that common thistle plants had allelopathic potential for eco-friendly vegetation management, and that especially their activities were differently exhibited depending on plant part.