Linderane protects pancreatic β cells from streptozotocin (STZ)-induced oxidative damage

Linderane, an important bioactive compound in Linderae, improved glucose and lipid metabolism in ob/ob mice. However, the effect of linderane on streptozotocin (STZ)-induced oxidative damage in INS-1 cells remains unclear. INS-1 cells were pre-treated with different doses of linderane for 2 h and then treated with 3 mM STZ for 12 h. Cell viability was determined by MTT assay. Cell apoptosis was detected using an Annexin V-FITC Apoptosis Detection Kit. The level of intracellular ROS was determined using dichlorofluorescein-diacetate (DCFH-DA). The activities of insulin secretion, SOD, catalase (CAT) and GPx were measured using ELISA kits. The expression levels of bax, bcl-2, p38, p-p38, nuclear Nrf2 and HO-1 were measured using western blot. The results showed that STZ-caused inhibitory effects on cell viability and insulin secretion were mitigated by linderane. Furthermore, linderane inhibited apoptosis and oxidative stress in STZ-induced INS-1 cells. Finally, linderane suppressed the activation of p38 MAPK pathway, as well as enhanced the activation of Nrf2 pathway in STZ-induced INS-1 cells. Activation of p38 MAPK pathway or inhibition of Nrf2 significantly reversed the protective effects of linderane against STZ-induced ROS production and cell apoptosis. The protective effects of linderane on STZ-induced INS-1 cells might be attributed to the inhibition of p38 MAPK and activation of Nrf2 pathway.