2.5. Iron chelating assay

The chelation of ferrous ions by quinoa leaf extracts was estimated using the method reported by Dinis et al. [9]. Briefly, 25 μL of 2 mM FeCl₂ was added to 0.25 ml of different concentrations of the crude extract (10, 50 and 100 mg/ml) and 0.05 ml of 5 mM ferrozine solution. The mixture was vigorously shaken and allowed to stand at room temperature for 10 min. The absorbance of the solution was thereafter measured at 562 nm and the inhibition percentage of ferrozine–Fe²⁺ complex formation was calculated as the same as the DPPH method described above.