Inhibitory effect of pomegranate on intestinal sodium dependent glucose uptake

Intestinal glucose uptake is mainly performed by its specific transporters, SGLT1 and GLUTs expressed in the intestinal epithelial cells. By using Caco-2 cells and 2-NBDG, we observed that intestinal glucose uptake was markedly inhibited by pomegranate (Punica granatum L, PG) among 200 screened edible Korean plants. The effects of the PG extract on Na(+)-dependent glucose uptake were further evaluated using brush border membrane vesicles (BBMV) obtained from the mouse small intestine. PG inhibited Na(+)-dependent glucose uptake with the IC(50) value of 424 μg/ml. The SGLT1 protein expression was dose dependently down regulated with PG treatment in Caco-2 cells. We next assessed the antihyperglycemic effect of PG in streptozotocin (STZ)-induced diabetic mice. Administration of PG (800 mg/kg) to STZ mice for four weeks improved postprandial glucose regulation. Furthermore, elevated Na(+)-dependent glucose uptake by BBMV isolated from STZ mice was normalized by PG treratment. These results suggest that PG could play a role in controlling the dietary glucose absorption at the intestinal tract by decreasing SGLT1 expression, and may contribute to blood glucose homeostasis in the diabetic condition.