The assay was carried out following the protocol reported by Dineshkumar et al. . Starch (2 mg) was suspended in a tube containing 0.2 mL of 0.5 M Tris-HCl (Sigma-Aldrich, USA) buffer (pH 6.9) with 0.01 M calcium chloride as substrate. The tube was boiled for 5 min and then preincubated at 37 \u00b0C for 5 min. Plant aqueous extract (1 mg) was dissolved with 1 mL of 0.1% of dimethyl sulfoxide in order to obtain a concentration of 1,000 \u00b5g\/mL; then 0.2 mL of aqueous extract was added to the tube containing the substrate solution, 0.1 mL of porcine pancreatic amylase in Tris-HCl buffer (2 U\/mL) was also added, and incubated for 10 min at 37 \u00b0C. Finally, the reaction was stopped with 0.5 mL of acetic acid (50% v\/v) and centrifuged 5 min at 1,811 \u00d7 g and 4 \u00b0C. The assay was performed in triplicate. The a-amylase inhibitory activity was calculated using the formula (Ac+) \u2013 (Ac-) \u2013 (As - Ab)\/(Ac+) \u2013 (Ac-) \u00d7 100, where Ac+, Ac-, As, Ab are defined as the absorbance (595 nm) of 100% enzyme activity (only solvent with enzyme), 0% enzyme activity (only solvent without enzyme), test sample (with enzyme), and a blank (a test sample without enzyme), respectively.