Determination of total flavonoids content (TFC)
The amount of TFC in the extracts was measured spectrophotometrically according to Djeridane et al. (2006). This method depends on the formation of a complex flavonoid aluminum, having the maximum absorbance at 430 nm. Rutin was used to make a calibration curve. One ml of methanolic extract was mixed with 1 ml of 2% AlCl3 methanolic solution. After incubation at room temperature for 15 min, the absorbance of the reaction mixture was measured at 430 nm. TFC was expressed as mg Rutin equivalents per g DM.