Inhibitory potential of trilobatin from Lithocarpus polystachyus Rehd against α-glucosidase and α-amylase linked to type 2 diabetes

The chemical structure of the sweet compound from Lithocarpus polystachyus Rehd was identified as trilobatin on the basis of HPLC, EIS-MS and NMR analyses. The inhibitory activities of trilobatin against alpha-glucosidase and alpha-amylase were evaluated, and the inhibition mechanism was analysed with Lineweaver-Burk plots. Also the antioxidant activity evaluation of trilobatin was conducted by DPPH radical scavenging assay. Comparing with acarbose, trilobatin showed a strong inhibitory activity against alpha-glucosidase and a moderate inhibitory activity against alpha-amylase. The Lineweaver-Burk plots analysis elucidated that trilobatin inhibited the enzyme non-competitively. DPPH scavenging activity of trilobatin (IC50 = 0.57 mg/ml) was higher than rutin (IC50 = 0.72 mg/ml), which indicated that trilobatin had a moderate antioxidant potential. These results suggest that trilobatin is a potential effective alpha-glucosidase inhibitor for management of postprandial hyperglycemia with less side effect, and provide strong rationale for further animal and clinical studies. (C) 2011 Elsevier Ltd. All rights reserved.