Components that demonstrate an α-glucosidase inhibitory activity and hyperglycemic inhibitory activity have clearly been provided from among the components included in Yacon. The present inventors found that as a result of screening for a strong anti-oxidant component in a Yacon aerial portion extract, an antioxidant activity was converged in a DIAION HP-20 column chromatography 50% methanol-eluted fraction of hot water extract. Thus, since a previously unidentified high-content component was confirmed, the present inventors conducted purification thereof, and thereby separated TCAA. As a result, this TCAA was found to be the component that demonstrates the α-glucosidase inhibitory activity and hyperglycemic inhibitory activity.
