Purification of a Component of the White-skinned Sweet Potato (Ipomoea batatas L.) with Antidiabetic Effects by Strong and Weak Anion Exchange Column Chromatography Steps

Abstract

The 22 kDa component of the white-skinned sweet potato (Ipomoea batatas L.) suppressed blood glucose elevation in the glucose tolerance test, although it has yet to be conclusively identified. In this study, we attempted to isolate and identify this component using an anion exchange resin column. Purification by weak anion exchange resin (TOYOPEARL DEAE-650M) separated an active fraction but could not isolate the active component. Purification by strong anion exchange resin (TOYOPEARL SuperQ-650M) isolated a component that was approximately 22 kDa, but it was not the active component. The active component, 22 kDa sporamin protein, was isolated by combining strong and weak anion exchange resin. These results showed that separation based on the difference in the adsorptive power of the ion-exchange resin was possible, and the component that suppresses blood glucose elevation is one of the components of sporamin with similar polymorphism.