Antioxidant properties and phenolic content of plant species occurring in Mediterranean grasslands

The assessment of antioxidant properties and phenolic content of grassland species is particularly useful for finding new sources for natural antioxidants, functional foods and nutraceuticals. Knowledge about antioxidant properties and phenolic content of many plant species used as traditional plant remedies is limited. We determined Trolox Equivalent Antioxidant Capacity (TEAC) by the two assays 1,1-diphenyl-2-picrylhydrazyl (DPPH) and the 2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) and the phenolic content by the Folin Ciocalteau method on 16 wild plant species, chosen among those traditionally used for ethnoveterinary practices. TEAC values exhibited extremely large variation, from 1.08 (Opuntia ficus indica) to 131.14 (Pistacia lentiscus) mmol TEAC 100 g-1 DW in the ABTS assay. Total phenolics, calculated as gallic acid equivalent (GAE), showed variation ranging from 12.7 (Hedera helix) to 147.68 (Pistacia lentiscus) g GAE kg-1 (DW). High TEAC values corresponded to high phenolic content, while plants with low antioxidant activity exhibited low total phenolic content. These results suggest that phenolic content might be useful as an indicator of antioxidant properties and encourage investigations on Mediterranean grassland species as sources of antioxidants.