Sanguinarine is a natural product, a chemical made by certain plants including the bloodroot plant (Sanguinaria canadensis), the Mexican prickly poppy (Argemone mexicana), Chelidonium majus, and Macleaya cordata. It is a slightly toxic polycyclic ammonium ion, an alkaloid, and has been demonstrated to have antitumour and antiviral properties. It also blocks the formation of blood vessels, it is antiangiogenic, and so has even greater potential as an anticancer agent.