*2.9. Determination of Antioxidant Capacity*

#### 2.9.1. Ferric-Reducing Antioxidant Power (FRAP) Assay

The ferric-reducing antioxidant power (FRAP) assay was carried out according to the procedures described by Gan et al. [28]. Briefly, the FRAP working solution was freshly prepared before the experiment, with sodium acetate solution (300 mM, pH = 3.7), TPTZ (10 mM solved with HCl) and ferric chloride solution (20 mM) mixedin a volume ratio of 10:1:1, respectively. The FRAP working solution was then incubated at 37 ◦C before use. The proper dilutions (100 μL) of samples were added to 3 mL of the FRAP working solution and their absorbance at 593 nm was determined after incubation for 4 min at room temperature (23 ± 1 ◦C). Ferrous sulfate solution (0.1–1 mM) was used as the standard for the calibration curve, and the results were expressed as mmol Fe(II)/g dry weigh (DW) extract powder. All tests were performed in triplicate.
