Antioxidant capacity and total phenolic content of selected plants from Turkey

A total of 28 different plants from different regions of Canakkale, Turkey, were investigated for their antioxidant capacity and total phenol contents to find new potential sources of natural antioxidants. The antioxidant capacity of methanolic extracts prepared from various parts of plants was evaluated by both trolox equivalent antioxidant capacity (TEAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, while the total phenolics were determined using the Folin-Ciocalteu method. The TEAC values of plant extracts ranged in a large scale from 1472.36 to 17.61 mu mol of trolox equivalents per g dry weight (dw), and EC50 values (concentration at which 50% radical scavenging occurred) varied from 0.174 to 42.475 mg dw of plant, while the total phenol content of plant extracts ranged between 117.20 and 1.27 mg of gallic acid equivalents per g dw. There was a positive linear correlation between the TEAC and total phenols of plant materials (r = 0.916). The extracts of Hypericum perforatum, Arbutus andrachne and Paliurus spina-christii showed higher antioxidant activities (both TEAC and DPPH assays). However, there was no clear relationship between TEAC and EC50 values (r = 0.477) of plant extracts.