Phloroglucinol Protects INS-1 Pancreatic β-cells Against Glucotoxicity-Induced Apoptosis

Decreasing numbers, and impaired function, of pancreatic β-cells are key factors in the development of type 2 diabetes. This study was designed to investigate whether phloroglucinol protected pancreatic β-cells against glucotoxicity-induced apoptosis using a rat insulinoma cell line (INS-1). High glucose treatment (30 mM) induced INS-1 cell death; however, the level of glucose-induced apoptosis was significantly reduced in cells treated with 100-μM phloroglucinol. Treatment with 10-100-μM phloroglucinol increased cell viability and decreased intracellular levels of reactive oxygen species, nitric oxide, and lipid peroxidation dose-dependently in INS-1 cells pretreated with high glucose. Furthermore, phloroglucinol treatment markedly reduced the protein expression of Bax, cytochrome c, and caspase 9, while increasing anti-apoptotic Bcl-2 protein expression. Cell death type was examined using annexin V/propidium iodide staining, revealing that phloroglucinol markedly reduced high glucose-induced apoptosis. These results demonstrated that phloroglucinol could be useful as a potential therapeutic agent for the protection of pancreatic β-cells against glucose-induced apoptosis.