No abstract

Hexane and methanol leaf extracts of sixteen Mediterranean plant species were obtained by percolation. Higher yields were observed for methanol (16.4–47.8%) than for hexane extracts (1.3–13%). Antioxidant activity of these extracts was determined by a rapid spectrophotometric method involving the combined oxidation of beta‐carotene and linoleic acid. Leaf extracts were thus characterized by an Antioxidant Activity Coefficient (AAC) ranging from 0 to 1000. Hexane extracts gave much higher AAC values than the corresponding methanol extracts. In both cases, myrtle (Myrtus communis) showed the best antioxidant effectiveness.

α‐Tocopherol was identified as the main antioxidant in hexane extracts of leaves of sixteen Mediterranean plant species. The α‐tocopherol content was determined by a two‐step procedure involving column and gas chromatography with α‐tocopherol acetate as internal standard. The tocopherol content of the extracts was in the range of 0.0–4.7%, and that of the dry leaves was 0–846 ppm. The highest α‐tocopherol content was found in the leaves of a Mediterranean oak,Quercus ilex. The antioxidative activity, which was previously investigated, was correlated with the α‐tocopherol content. Correlation coefficients were 0.947 and 0.904 for extracts and leaves, respectively.