2.6. Determination of metal chelating capacity

Metal chelating activity was measured by the method described by Chew et al. (2000). 0.1 mM FeSO₄ and 0.25 mM of ferrozine, forming an Fe²⁺-ferrozine complex, were subsequently added into 0.2 mL of the extract. After incubation at room temperature for 10 min, absorbance of the mixture was recorded at 562 nm. EDTA was used as a positive control.