This study aims to investigate the total antioxidant capacity (TAC) as trolox equivalent (mmol g as a potential source of natural antioxidants to be incorporated in current diets to protect human health. CUPRAC method proved to be most effective among electron-transfer based TAC assays since it responded to a wide variety of hydrophilic and lipophilic antioxidants.-Keywords: ayvalik food plants, antioxidant capacity, CUPRAC (cupric reducing antioxidant capacity) assay *To whom correspondence should be addressed. Email: rapak@istanbul.edu.tr
IntroductionThe quality of food has increased by using antioxidants which have prevented or delayed their oxidative deterioration during processing and storage (Cosio et al., 2006). Wild plants, vegetables and fruits have attracted much attention as sources of natural antioxidants. Many of the wild plants, vegetables and fruits contain antioxidants such as vitamins (β-carotene, vitamins C and E), and polyphenols (flavonoids, tannins, catechins) (Wong et al., 2006). Epidemiological studies have shown that a diet rich in vegetables and fruits can reduce the incidence of cardiovascular diseases and of certain cancers (Ames, 1983;Block et al., 1992).Ayvalik is located in the northwestern part of Anatolia (Turkey) where the use of wild edible plants is a practice that has developed over generations and is part of the local traditional knowledge system. The Maritime climate dominates in Ayvalik where the summers are hot and dry while the winters tepid and rainy (Temucin, 1993). The sub-humid climate around Ayvalik enables the widest distribution of plant species. The inhabitants in Ayvalik consume the aerial parts of various food plants listed in Table 1 with botanic, English, and local names. Esiyok et al. (2004) have reported a brief overview of important herbs in the Turkish flora, including fennel, mallow, chicory, nettle, wild radish, and wild mustard, as important food plants for promoting human health and preventing cancer.Total antioxidant capacity may better reflect the health beneficial quality of foods than individual measurements due to the possible cooperative action of antioxidants (Ghiselli et al., 2000). The aim of this study is to investigate the total antioxidant capacity as trolox equivalent (mmol g -1 ) of nine- et al., 2004; 2005; 2006; 2008), ABTS/persulfate (Re et al., 1999), FRAP (Benzie andStrain, 1996) and Folin (Singleton et al., 1999) assays. Additionally, three antioxidant assay methods with the exception of Folin were used to determine the antioxidant capacity of F. vulgare for the first time.
Materials and MethodsMaterials Neocuproine and Folin-Ciocalteou reagent were purchased from Sigma Chemical Co. (Sigma-Aldrich GmbH, Steinheim, Germany). Trolox was obtained from Aldrich Chemicals Co. (Sigma-Aldrich GmbH, Steinheim, Germany). Ammonium acetate, copper (II) chloride, potassium persulfate, hydrochloric acid, sodium hydroxide, copper (II) sulfate, sodium carbonate, sodium potassium tartarate, glacial acetic acid, sodium acetate trihydrate, ferric c...