Inhibitory Effect of Boesenbergia rotunda and Its Major Flavonoids, Pinostrobin and Pinocembrin on Carbohydrate Digestive Enzymes and Intestinal Glucose Transport in Caco-2 Cells.

Boesenbergia rotunda (L.) Mansf., commonly known as fingerroot or "Kra-Chai," is a traditional Thai medicinal plant used for treating digestive and metabolic disorders. Recent evidence highlights its potential role in controlling hyperglycemia, though its active compounds and mechanisms remain unclear. This study evaluated the antidiabetic activity of B. rotunda crude extract and its major flavonoids, pinostrobin and pinocembrin, through in vitro enzyme inhibition and cellular glucose transport assays. Pinocembrin exhibited the strongest inhibition of both α-amylase and α-glucosidase, while pinostrobin and the crude extract showed moderate effects. In Caco-2 cells, the crude extract reduced glucose uptake, whereas both flavonoids markedly inhibited transport under glucose-depleted conditions, suggesting interaction with sodium-dependent glucose transporters (SGLTs). Under high-glucose conditions, their effects were minimal, indicating limited activity on facilitative glucose transporters (GLUTs). Moreover, molecular docking studies revealed that pinostrobin and pinocembrin bind within the glucose transporter channels of SGLT1 and SGLT2, blocking glucose passage and supporting the experimental findings. Overall, B. rotunda, particularly pinocembrin, demonstrates notable in vitro antidiabetic potential through enzyme inhibition and SGLT modulation. Further in vivo investigations are warranted to validate its hypoglycemic properties and identify additional active compounds.