Effect of Olive Leaf )Olea europaea L. (on Glucose-stimulated Insulin Secretion from Isolated Pancreatic Islets of Rat

Abstract

Background: The traditional use of medicinal plants to treat diabetes mellitus after using synthetic oral hypoglycemic agents and insulin is point to search for safer and more effective drugs of plant origin, although study of their mechanism have been continued. Olive tree and its products have important components of a healthy diet because of their phenolic content. Objective: We are interested to investigate the effects of the methanol extraction of Olea europaea leaf on insulin secretory function of pancreatic islets which were isolated freshly from rat. Methods: Plants were extracted with methanol and then powdered through freeze-drying. Islets were isolated from male adult pancreas and cultured overnight, preincubated in glucose 2.8 mM then incubated at 37 ºC in the presence of basal (2.8 mM) and stimulatory (16.7 mM) doses of glucose, with different doses of plants extracted (0.01, 0.05, 0.1, 1 mg/ml), after 30 min incubation the secreted insulin was assayed by ELISA kit. Results: Data indicated that Olea europaea leaf extract at concentration of 0.05 mg/ml plus basal glucose could enhance insulin secretion from isolated pancreatic islets compared to control group which exposed just to basal glucose, significantly (4.2 ± 0.48 vs 10.5 ± 0.29 µg/l) (p<0.05), also compared to other groups. Although it could increase insulin secretion at stimulant glucose level but it was not significant. Conclusion: Olive leaf extract, probably without metabolic transformation, could increase insulin secretion from freshly isolated pancreatic islets of rat at basal glucose level significantly, which point to that its affect might be akin to glucose.

Keywords

• pancreatic islets
• olive leaf
• diabetes
• insulin
• glucose