Bioassay guided fractionation from corn gluten meal, a byproduct of a starch manufacturing plant, gave N-p-coumaroyl-N'-feruloylputrescine (1) and N,N'-diferuloylputrescine (2) as alpha-glucosidase inhibitors. Some structure-activity relationships were studied by comparing the inhibitory activity by preparing some related compounds, and it was revealed that the hydroxyl group was important for the inhibitory activity of bisamide alkaloids, but not the redox potential.