The chelating activity was measured

The chelating activity was measured based on the method de- scribed by Dinis et al.18 50 lL of sample was diluted with 100 lL of D.I. water. The diluted solution was mixed with 25lL of 0.5 mM FeCl2 and 25 lL of 2.5 mM ferrozine. The mixture was kept in the dark at room temperature for 10 min. EDTA-2Na was used as a positive control. The absorbance of each mixed sample was mea- sured using the ELISA reader at 550 nm wavelength. Each measure- ment was made at least in duplicate. The chelating activity was calculated by using Eq. 3.