In vitro α-Glucosidase Inhibition Activity

Standard procedure with little modification was adopted for examination of the α-glucosidase inhibitory potentials (10). Exactly, a 20-μl extract of various doses (62.5, 125, 250, 500, and 1,000 μg/ml) was incubated at 37°C with 50 μl of 100-mM phosphate buffer (pH 6) and 10-μl α-glucosidase (1 U/ml) in a 96-well plate for 15 min. Twenty microliters of 5-mM p-nitrophenol-glucopyranoside was added as substrate followed by additional incubation for 20 min at 37°C. The reaction was completed after the addition of 0.1 M 50 μl sodium carbonate. The absorbance was calculated for released p-nitrophenol by Multiplate Reader at 405 nm. Acarbose served as reference. The results were calculated as:

where A_Background, A_Blank, and A_Sample are absorbance of 100% enzyme activity (solvent plus enzyme), blank (test sample having no enzyme), and test sample (having enzyme), respectively.