Swietenine and swietenolide from Swietenia macrophylla king improve insulin secretion and attenuate apoptosis in H2O2 induced INS-1 cells

Oxidative stress is an important factor that causes pancreatic beta-cell dysfunction leading to the development and aggravation of diabetes. Swietenine (Stn) and swietenolide (Std) were isolated from the fruits of Swietenia macrophylla King and had the potential effects on treatment and prevention of diabetes. The aim of this study is to investigate the effects of Stn and Std on insulin secretion and apoptosis in H2O2 induced insulinoma cell line (INS-1) cells. In the present study, INS-1 cells were treated with 300 mu M H2O2 for 4 h to establish the oxidative damage model. Cell apoptosis, insulin secretion, reactive oxygen species (ROS), superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH) levels, and Caspase-3 enzyme activity were measured via corresponding methods. Finally, pancreatic duodenal home box factor-1 (PDX-1), B cell lymphoma-2 (Bcl-2), and Bax protein expression were detected by western blot. Experimental results showed that Stn and Std could significantly improve the INS-1 cell viability, increase the secretion of insulin and reduce the ROS level in H2O2 induced INS-1 cells. Furthermore, the SOD and GSH levels increased, and the MDA levels decreased compared with the model group after Stn and Std treatment. In addition, after treated with Stn and Std, cell apoptosis was improved, and the activity of Caspase 3 was also significantly inhibited. Meanwhile, Western blot results showed that Stn and Std could up-regulate the expression of PDX-1 protein, and affect the cell apoptosis pathway by up-regulating the expression of Bcl-2 protein and down-regulating the expression of Bax protein. In conclusion, Stn and Std can signifcantly improve the insulin secretion function, protect oxidative stress injury, and reduce apoptosis in H2O2 induced INS-1 cells, which provides a research basis for Stn and Std to be new drug candidates for the treatment and prevention of diabetes.