Antidiabetic actions of aqueous bark extract of Swertia chirayita on insulin secretion, cellular glucose uptake and protein glycation

Objective: There is renewed scientific interest in the potential of plant-derived agents for the treatment ofdiabetes mellitus. This study investigated the antidiabetic actions of Swertia chirayita, a plant used traditionally inthe management of diabetes. Materials and Methods: Insulin secretion from BRIN-DB11 cells was assessedin the absence or presence of plant extract and modulators of beta cell function. Glucose uptake was assessedusing 3T3-L1 cells while effects of the plant extract on protein glycation was assessed using model peptide.Insulin was measured by radioimmunoassay and intracellular calcium by FlexStation®. Results: S. chirayitasignificantly stimulated concentration-dependent insulin secretion from BRIN-BD11 cells. Its insulinotropiceffects were abolished in the absence of extracellular Ca2 + or by diazoxide and were significantly decreasedby verapamil and in beta cell depolarization with KCl. S. chirayita extracts evoked a 28-59% increase in basaland insulin-stimulated glucose uptake by 3T3-L1 cells. Protein glycation was significantly inhibited by S. chirayitain a dose-dependent manner. Conclusion: This study reveals that the antidiabetic actions of S. chirayitaaqueous bark extracts involves the stimulation of insulin secretion and enhancement of insulin action. Inhibitionof protein glycation may also help counter diabetic complications. These actions of S. chirayita may providenew opportunities for the treatment of diabetes.