The chelating activity of AA and GA on Fe2+ was
measured according to the method of Dinis, Madeira,
and Almeida (1994). AA and GA (0.004–4.17 mM) were
reacted with FeCI2 (2 mM, 0.2 ml) and ferrozione (5
mM, 0.2 ml) for 10 min, and the spectrophotometric
absorbance was determined at 562 nm. A lower level of
absorbance indicated a stronger chelating activity.