– Per cent α-glucosidase inhibition per GPE sub-fraction. Enzyme activity was determined by measuring p-nitrophenol release from pNPG at 405 nm. Acarbose (50 µg/mL) is the standard and denoted as Std. C18, HP20, SPE, S1, and S2 stand for reversed-phase C18 column, Diaion resin HP-20 column, solid phase extraction column, silica gel column, and smaller silica gel column, respectively. Bars marked with different superscripts are significantly different (p < 0.05).