3. Ferric reducing antioxidant powe

3. Ferric reducing antioxidant power (FRAP)
assay
The FRAP, a method for measuring total reducing power of electron donating substances,was assessed according to Benzie and Strain (1999).Briefly, 6 ml of working FRAP reagent (0.1 M acetate buffer:0.02 M FeCl3:0.01 M TPTZ = 10:1:1) prepared daily was mixed with 20 μl of extract sample. The absorbance at 593 nm was recorded after a 30-min incubation at 37oC. FRAP values were obtained by comparing with standard curves created by Trolox (0-35 μg) and vitamin C (0-15 μg), and reported as mg Trolox and vitamin C equivalent per gram of dry weight.