A pyrrolizidine alkaloid with hepatotoxic properties; metabolized by CYP3A in the liver to the detoxification product senecionine N-oxide and reactive metabolites including dehydropyrrolizidine alkaloids and dehydrotetronecine; induces mitochondrial depolarization and fragmentation in primary cultured mouse hepatocytes at 20 μM and increases apoptosis in a concentration-dependent manner; induces liver injury, increases serum levels of bilirubin and various bile acids, including taurocholic acid, glycocholic acid, and deoxycholic acid, and increases the activity of alanine aminotransferase and aspartate aminotransferase in serum in rats at 35 mg/kg; hepatotoxicity is also associated with lipid peroxidation and glutathione depletion