Inhibition of glucose intestinal absorption by kaempferol 3-O-α-rhamnoside purified from Bauhinia megalandra leaves

Glucose intestinal absorption (GIA) is one of the factors that increase glycemia. Its reduction could be an important factor in decreasing hyperglycemia in diabetic patients. It has been shown that the aqueous extract of Bauhinia megalandra leaves inhibits GIA. In the present study we identified a compound present in the extract of B. megalandra responsible for the biological effect. The methanol extract of B. megalandra leaves was fractionated using different solvents, and high-speed counter-current chromatography yielding two pure compounds identified by 1H NMR and 13C NMR as kaempferol 3-O-α-rhamnoside and quercetin 3-O-α-rhamnoside. The first one increased the KM without changes in the VMAX of GIA. In addition it exerted an additive inhibitory effect, on GIA, when combined with phlorizin. We suggest that kaempferol 3-O-α-rhamnoside is a competitive inhibitor of intestinal SGLT1 cotransporter.

Graphical abstractA decrease in glucose intestinal absorption (GIA) could be an important factor in reducing hyperglycemia in diabetic patients. It has been shown that extract of leaves from Bauhinia megalandra inhibits GIA: We identified a compound present in B. megalandra responsible for this biological effect. The methanol extract of B. megalandra leaves was fractioned, using different solvents and high-speed counter-current chromatography yielding kaempferol 3-O-α-rhamnoside and quercetin 3-O-α-rhamnoside. The first compound increases the KM without changes in the VMAX of GIA. In addition it exerted an additive effect with phlorizin. Therefore, we suggest that it is a competitive inhibitor of the SGLT1 cotransporter.Figure optionsDownload full-size imageDownload as PowerPoint slide