Determination of total phenolic compounds
Antioxidant compounds generally contain phenolic group(s). Because of this, amounts of phenolic compounds in each of the extract were compared to obtain more information about the extract(s) which posses(s) antioxidant potential. This was carried out as described previously (Yıldırım et al., 2003). Briefly, extract solution was transferred into a tube and then final volume was adjusted to 4 ml by addition of distilled water. Afterward, 0.25 ml of Folin-Ciocalteu Reactive (FCR) (Fluka) was added into this mixture and after 3 min 0.75 ml of Na2CO3 solution was added. Subsequently, mixture was shaken on a shaker for 2h at room temperature and then absorbance was measured at 760 nm. Amount of total phenolic compounds were carried out for two sample replications, and values are an average of two replicates. Gallic acid was used as the standard for a calibration curve. The phenolic compound content was expressed as gallic acid equivalent using the following equation based on the calibration curve: