ANTIOXIDANT ACTIVITY OF PLANT-LEAVES IN RELATION TO THEIR ALPHA-TOCOPHEROL CONTENT

The leaf alpha-tocopherol content of fifteen plant species was determi ned by a gas-chromatographic method with alpha-tocopherol acetate used as internal standard. Highest amounts were found in leaves of Pelargo nium sp. (412 ppm) and Thalictrum flavum (371 ppm), which could repres ent an interesting source of alpha-tocopherol for different purposes, such as the stabilization of food products. Antioxidant activity of le af extracts was evaluated spectrophotometrically by coupled oxidation of beta-carotene and linoleic acid. The species could thus be ranked o n the basis of an antioxidant-activity coefficient. Correlation establ ished between the alpha-tocopherol content and antioxidant activity yi elded a coefficient of 0.93, suggesting that alpha-tocopherol is the m ajor liposoluble antioxidant found in leaves.