Search for α-glucosidase and α-amylase inhibitors from Indonesian medicinal plants

One effective way to treat diabetes is to suppress carbohydrate digestion due to utilization of α-amylase and/or α-glucosidase inhibitors. The objective of our research was to explore the potential of Indonesian medicinal herbs for putative antidiabetic activity via inhibition of α-amylase and α-glucosidase. In vitro activity was determined via inhibition of sucrose and/or maltose hydrolysis by rat intestinal α-glucosidase, and starch azure hydrolysis by porcine pancreatic α-amylase. Among 57 samples that were found to have strong inhibitory activity against α-amylase and/or α-glucosidase, 17 species are here reported for the first time to be potential anti-diabetic herbs. Among these, Macaranga tanarius leaves inhibited both α-glucosidase and α-amylase. Five ellagitannins showing inhibitory activity against rat intestinal maltase were successfully isolated and identified. Of the isolated compounds, two were new and were named macatannins A (IC50=0.80 mM) and B (IC50=0.55 mM), while the other compounds were identified as mallotinic acid (IC50 >5.00 mM), corilagin (IC50=2.63 mM), and chebulagic acid (IC50=1.00 mM).