Novel α-glucosidase inhibitors from Macaranga tanarius leaves

One of the hyperglycaemic remedies is glucose absorption reduction by suppressing carbohydrate digestion due to utilisation of α-glucosidase inhibitors (AGIs). Determination of prospecting herbs done in vitro by using enzyme assay resulted in the finding of Macaranga tanarius, which showed a potent inhibitory activity. An EtOAc-soluble extract of M. tanarius leaves was chromatographed by a Diaion HP-20 column and the active fractions were further purified with high performance liquid chromatography (HPLC) to isolate active principles against α-glucosidase. Five ellagitannins were successfully isolated and identified. Structure determination revealed that these isolated compounds were mallotinic acid (IC50 > 5.00 mM), corilagin (IC50 = 2.63 mM), chebulagic acid (IC50 = 1.00 mM), and two novel compounds named macatannins A (IC50 = 0.80 mM) and B (IC50 = 0.55 mM). AGIs play an important role for the treatment of diabetes, therefore this research results may suggest novel alternatives for diabetes treatment management.