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OBJECTIVE:To investigate the effect of mulberry leaf flavonoids (MLF) on apoptosis of pancreatic cells induced by high glucose.METHODS:Long exposure to high glucose induces apoptosis of pancreatic β cells,which can lead to diabetes.In this study,we used the rat insulinoma cell line,INS-1.High glucose (33.3 mM) was used to establish a glucotoxicity model.The MTT assay was used to evaluate the MLF effect on cell viability.INS-1 cells were treated with various concentrations of MLF (125,250 and 500 mg/L) for 24 h,and then stimulated with 5.5 or 33.3 mM glucose for48 h.Then,the cell supatants were collected for enzyme-linked immunosorbent assay to determine the level of superoxide dismutase (SOD),catalase (CAT),glutathione peroxidase (GSH-Px),malondialdehyde (MDA),monocyte chemoattractant protein 1 (MCP-1),tumor necrosis factor a (TNF-α) and interleukin 6 (IL-6).West blotting was used to determine the expression of Bcl-2,Bax,caspase-3 and Caspase-9.Cell apoptosis was measured by Annexin V-FITC/propidium iodide double staining and flow cytometry.RESULTS:MLF (125-500 mg/L) improved cell viability.Furthermore,MLF (250 and 500 mg/L) inhibited apoptosis induced by high glucose.The anti-apoptosis effect of MLF was associated with increased SOD,CAT and GSH-Px expression,as well as reduced MDA levels in high-glucose-treated INS-1 cells.Moreover,MLF upregulated Bcl-2 expression,downregulated Bax expression,and reduced the expression of caspase-3 and Caspase-9.Finally,MLF decreased the secretion of inflammatory cytokines and insulin in high-glucose-induced INS-1 cells.CONCLUSION:MLF is a potential therapeutic agent for preventing diabetes and related disorders.