α-Glucosidase (EC 3.2.1.20, S. cerevisiae, Sigma catalog #G0660) inhibitory activity was assayed by using 0.1 M phosphate buffer (pH 6.8) at 37 °C [35]. The enzyme (0.2 U/mL) in phosphate buffer saline was incubated with various concentrations of test compounds at 37 °C for 15 min, test compounds were dissolved in DMSO (final concentration 7%). The substrate and p-nitrophenyl α-d-glucopyranoside (0.7 mM, final) were added and change in absorbance at 400 nm was monitored up to 30 min. Test compound was replaced by DMSO (7% final) as control. Acarbose was used as the standard inhibitor. The percent inhibition was calculated by using the following formula: