Lasiocarpine is toxic only after its metabolic conversion to the toxic intermediate, known as dehydrolasiocarpine.
Dehydrolasiocarpine and other putative didehydropyrrolizidine alkaloids (the pyrrolic esters) are very reactive,they attack nucleophilic macromolecules such as DNA and proteins, eliciting severe toxicities, including liver veno-occlusive disease and tumors.
Lasiocarpine is mainly metabolized in vitro through five metabolic pathways, dehydrogenation, ester bond cleavage, demethylation.