Endocrine Abstracts

Traditional plant treatments have been used throughout the world for the therapy of diabetes mellitus. The aim of this study was to investigate the efficacy and mode of action of Terminalia bellerica Roxb. (Combretacea) used traditionally for treatment of diabetes in India. Terminilia bellerica aqueous extract stimulated basal insulin output and potentiated glucose-stimulated insulin secretion concentration-dependently in the clonal pancreatic beta cell line, BRIN-BD11 (P<0.001). The insulin secretory activity of plant extract was abolished in the absence of extracellular Ca²⁺ and by inhibitors of cellular Ca²⁺ uptake, diazoxide and verapamil, (P<0.001, n=8). Furthermore, the extract did not increase insulin secretion in depolarised cells and did not further augment insulin secretion triggered by tolbutamide or glibenclamide. Terminilia bellerica extract also displayed insulin mimetic activity and enhanced insulin-stimulated glucose uptake in 3T3 L1 adipocytes by 300%. At higher concentrations, the extract also produced 10–50% (P<0.001) decrease in starch digestion in vitro and inhibited protein glycation (P<0.001).

In Streptozotocin (125 mg/kg body weight) diabetes-mice, long term administration of T.bellerica decoctions (5 mg/ml) reduced (P<0.01) diabetic polydepsia, with no parallel recorded improvements of glucose homeostasis parameters.

This study has revealed that components in T. bellerica extract stimulate insulin secretion, enhance insulin action and inhibit both protein glycation and starch digestion. The former actions are dependent on the active principle(s) in the plant being absorbed intact. Future work assessing the use of Terminalia bellerica as dietary adjunct or as a source of active antidiabetic agents may provide new opportunities for the treatment of diabetes.