2.3. α-Glucosidase inhibition assay

The method used to assess rat α-glucosidase inhibition was adapted from Adisakwattana, Charoenlertkul, & Yibchok-anun, 2009 as modified by Nyambe-Silavwe & Williamson, 2016. An assay volume of 500 μL was used and consisted of 50 μL of sodium phosphate buffer (10 mM, pH 7), 50 μL of potential inhibitor, 200 μL of acetone-derived protein intestinal extract from rat intestine (4 mg solid/mL for maltose) and 200 μL of substrate (3 mM maltose) (Nyambe-Silavwe & Williamson, 2016). Sodium phosphate buffer (50 μL) was put in place of the potential inhibitor for the control sample. The reaction was carried out at 37 °C for 20 min by adding the enzyme source to a mixture of sodium phosphate buffer, potential inhibitor and substrate. The reaction was stopped by heating in a water bath at 100 °C for 10 min, cooled to room temperature, polyphenols removed by solid phase extraction, hexokinase reagent added and absorbance read at 340 nm in a plate reader. Inhibition in the samples was calculated as a percentage of the control.