The metal chelating assay was performed according to the method previously described by Chan et al. (2007) with BHT being used as the positive control. In short, 1 ml of individual lotus extract (ranged from 1 to 5 mg/ml) was separately mixed with equal volume of FeSO4 (0.1 mM) and ferrozine (0.25 mM) followed by vigorous shaking. After incubation for 10 min, absorbance of the reaction mixture was measured colorimetrically at 562 nm, while the metal chelating ability (%) of each lotus extract was calculated by the equation as described in the DPPH radical scavenging assay.