Hypoglycemic effect of silychristin A from Silybum marianum fruit via protecting pancreatic islet β cells from oxidative damage and inhibiting α-glucosidase activity in vitro and in rats with type 1 diabetes

In the present study, the hypoglycemic effect of silychristin A on streptozotocin (STZ)-induced type 1 diabetes in rats was evaluated and the underlying pharmacological mechanism was further elucidated in vitro. Silychristin A significantly lowered the glucose level, increased insulin secretion, and improved the structure of β cells in STZ-induced rats. Accordantly, reactive oxygen species (ROS) production induced by STZ or high concentration of glucose (HG) was effectively suppressed by silychristin A in pancreatic INS-1 β cells evaluated by flow cytometry. Western blot analysis demonstrated that silychristin A markedly suppressed STZ or HG induced cell apoptosis. In addition, in vitro inhibitory effect of silychristin A on α-glucosidase and molecular docking analysis revealed that silychristin A could reduce the digestion rate of carbohydrates. These findings indicate that silychristin A may be useful as a potential functional food ingredient against oxidative stress-mediated destruction of pancreatic islet β cells and inhibition of α-glucosidase activity.