Antidiabetic Properties of an Apple/Kale Extract In Vitro, In Situ, and in Mice Fed a Western-Type Diet.

Type 2 diabetes mellitus (T2DM) is a common and increasingly prevalent metabolic disorder, and effective preventive strategies against this disease are needed. The aim of the present study was to evaluate the potential antidiabetic properties of a dietary apple/kale extract (AKE), which was rich in phlorizin and flavonoids, in laboratory mice. Mice were fed a control diet, a Western-type high-sugar, high-fat diet (WTD), or a WTD plus AKE for 10 weeks. Body weight, food and energy intake, body composition, and blood glucose level were recorded in addition to the postprandial rise in blood glucose concentration after a single administration of glucose (oral glucose tolerance test, OGTT). Furthermore, changes in glucose-induced short-circuit current (I-SC) in response to AKE and phlorizin administration were evaluated in situ in intestinal tissues with Ussing chambers. In addition, the in vitro inhibition of alpha-glucosidase by AKE was determined. The present data suggest that supplementation of an AKE to a WTD significantly improved both blood glucose levels and OGTT in mice. Furthermore, in situ uptake of glucose was significantly inhibited by AKE. Finally, we showed that AKE significantly inhibits alpha-glucosidase activity in vitro. We conclude that AKE exhibits antidiabetic properties by a dual mechanism, including the inhibition of a-glucosidase and sodium-dependent glucose transporter 1 (SGLT1). Thus, AKE has the potential to serve as a natural plant bioactive compound for dietary prevention strategies against T2DM.