Abstract: OBJECTIVE: To evaluate the effect of Nelumbo Nucifera leaf water extract(NNLE) on insulinoma(RIN)cells induced by interleukin-1β(IL-1β) and interferon-g(IFN-γ), and injured pancreatic β-cells induced by Streptozotocin(STZ) in rats.METHODS: The anti-oxidative effects of NNLE were assessedusing 1,1-diphenyl-2-picrylhydrazyl(DPPH)and nitric oxide(NO) scavenging assays. The inhibitory effect of NNLE on α-glucosidase and DPP(dipeptidyl peptidase)-IV was measured in vitro. Pancreatic β-cell protective and insulin secretory effects were assessed, using IL-1β and IFN-γ-induced rat RIN cells. STZ-induced diabetic rats were treated with 50, 100, and 400 mg/kg NNLE for 4 weeks. The effects of NNLE on blood glucose(BG), body weight(BW), and lipid profiles were measured.RESULTS: NNLE inhibited DPPH, NO, α-glucosidase,and DPP-Ⅳ which were directly linked to the function of β-cells. Furthermore, NNLE protected RIN cells from toxicity induced by IL-1β and IFN-γ, decreased NO production, and increased insulin secretion. NNLE caused a significant reduction in blood glucose, triglyceride(TG), total cholesterol(TC),blood urea nitrogen(BUN), and creatinine in STZ-induced diabetic rats. Furthermore, it significantly decreased BW loss in STZ-induced diabetic rats.CONCLUSION: Our results suggest that NNLE reduced the toxicity in insulinoma cells and increased insulin secretion in pancreatic β-cells in STZ-induced diabetic rats.

Key words: Nelumbo Nucifera, Diabetes mellitus, Insulin, Interleukin-1beta, Interferon-gamma, Insulin-secreting cells, Streptozotocin, Glucose