2.4.3. Metal chelating assay
Chelating ability was determined according to the previously
reported procedure with a slight modification (Dinis, Madeira, &
Almeida, 1994). The different concentrations of samples
(0.2e1.0 mg/mL, 1 mL) were mixed with 3.7 mL of methanol and
0.1 mL of 2 mM ferrous chloride. The reaction was initiated by the
addition of ferrozine (0.2 mL, 5 mM). After 10 min at room
temperature, the absorbance of the mixture was determined at
562 nm against a blank. EDTAwas used for comparison. The ferrous
ion-chelating activity was given by the following equation: