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 α-glucosidase and α-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 α-glucosidase and a moderate inhibitory activity against α-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 α-glucosidase inhibitor for management of postprandial hyperglycemia with less side effect, and provide strong rationale for further animal and clinical studies.