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

•Silychristin A was purified from the fruit of Silybum marianum.•Silychristin A exhibits significant hypoglycemic effect.•Silychristin A improves insulin secretion by protecting pancreatic β cells.•Silychristin A shows potent α-glucosidase inhibitory activity.•Silychristin A protects pancreatic β cell line INS-1 from ROS-induced apoptosis.