3.6. In Vitro α-Glucosidase Inhibition Study

The α-glucosidase inhibition assay used 4-nitrophenyl-α-d-glucopyranoside as substrate. 20 μL aliquots of the sample (in five different concentrations) or negative and positive control solutions were each mixed with 70 μL enzyme solution (1 U/mL) in 0.1 M PBS (pH 6.8). After incubation at 25 °C for 10 min, 100 μL of 4 mM pNPG solution in PBS was added and incubated in a 96-well microplate for 5 min at 25 °C. The absorbance was measured at λ 405 nm using a microplate reader (Biotek, Bad Friedrichshall, Germany). Each sample was measured in triplicate.