Modes of α-glucosidase inhibition for polyphenols derived from soybeans. To calculate the mode of action, Lineweaver–Burk plots were constructed: (A) Acarbose (closed triangle, 100 μM; open square, 300 μM; closed diamond, 1000 μM; open circle, 3000 μM), (B) glyceollin (closed triangle, 1 μM; open square, 3 μM; closed diamond, 10 μM; open circle, 30 μM), (C) genistein (closed triangle, 1 μM; open square, 3 μM; closed diamond, 10 μM; open circle, 30 μM), (D) luteolin (closed triangle, 1 μM; open square, 3 μM; closed diamond, 10 μM; open circle, 30 μM), and (E) daidzein (closed triangle, 1 μM; open square, 3 μM; closed diamond, 10 μM; open circle, 30 μM).