Antioxidant and free radical scavenging activities of 5,7,3'-trihydroxy-3,6,4'-trimethoxyflavone from Brickellia veronicaefolia.

The antioxidant and antiradical activities of 5,7,3'-trihydroxy-3,6,4'-trimethoxyflavone or centaureidin isolated and characterized from Brickellia veronicaefolia were elucidated by heat-induced oxidation in a beta-carotene and linoleic acid system and by the 1,1-diphenyl-2-picrylhydrazyl decoloration test. The centaureidin (32.1%) exhibited antioxidative activity less than that of BHT (95.5%) and alpha-tocopherol (95.9%) on oxidation in a beta-carotene and linoleic acid system. A moderate antiradical effect (47.6%) compared with BHT (96.7%) and alpha-tocopherol (94.6%) in DPPH decoloration test was found.