3.2. In Vitro α-Glucosidase Inhibition Assay

α-Glucosidase inhibition was tested according to previously reported methods with some modifications [28]. 8 µL of CSEs or control (Acarbose) in DMSO were added to 115 µL of 0.1 M sodium phosphate buffer pH 7.0 in a 96 well microtiter plate (50 µg/mL final concentration). Fifty microliters of yeast α-glucosidase enzyme solution (0.5 U/mL in phosphate buffer) was added to the wells. The plate was incubated at 37 °C for 15 min. Next, 25 µL of 2.5 mM PNPG (4-nitrophenyl α-d-glucopyranoside) substrate solution (in phosphate buffer) was added. The microplate was incubated at 37 °C for another 15 min. The absorbance was then measured using a microplate reader at 405 nm. The percentage inhibition was calculated using the formula: