2007 Volume 54 Issue 12 Pages 563-567
Polyphenols were prepared from seven kinds of edible legumes in the family Fabaceae using a two-step extraction with 80% ethanol and 70% acetone. The resulting polyphenols were compared for antioxidant and inhibitory activity on α-amylase and α-glucosidase. Adzuki bean contained the largest amount of polyphenols, followed by kidney bean, black gram, black soybean, green gram, and soybean. Antioxidant activity was significantly correlated with the concentrations of monomer- and oligomer-type polyphenols. Polyphenols from peas and soybean were mostly of the monomer-type and had little inhibitory activity against glycosidases. The oligomer-type comprised 67-76% of polyphenols from Adzuki bean, kidney bean, and black gram. Extracts from these legumes showed antioxidant and glycosidases inhibitory activity. Polyphenols from green gram and black soybean poorly inhibited α-amylase but effectively inhibited α-glucosidase. Legume oligomer-type polyphenols inhibit both α-amylase and α-glucosidase, but monomer-type polyphenols possess mainly antioxidant activity.
