Aqueous bark extracts of terminalia arjuna stimulates insulin release, enhances insulin action and inhibits starch digestion and protein glycation in vitro

Abstract

Scientific evidence for the effects of Terminalia arjuna on diabetes mellitus is lacking. This study investigated the anti-diabetic efficacy and mode of action of the bark extract of Terminalia arjuna. Insulin-release from BRIN-BD11 cells was assessed in the absence or presence of T. arjuna extracts and modulators of insulin-secretion. Insulin concentration and intracellular calcium ([Ca2+]i) were measured by radioimmunoassay and FLEXstationTM respectively. Adipocyte glucose-uptake with 3T3-L1 fibroblasts, starch digestion with α–amylase and protein glycation were assessed in vitro. Terminalia arjuna extract stimulated insulin-release alone (p<0.001), in combination with known modulators but not without extracellular Ca2+. It increased intracellular calcium but had no effects on depolarised cells. Glucose-uptake was enhanced in the presence of T. arjuna (P< 0.001). At higher concentrations, the extract decreased starch digestion and inhibited protein glycation (p<0.001). Terminalia arjuna extract possesses antidiabetic potential and may provide new opportunities for the treatment of diabetes.