Mimosine or leucenol is an alkaloid, beta-3-hydroxy-4 pyridone amino acid. Mimosine is an effective inhibitor of DNA replication in mammalian cells. It blocks entry into S phase (late G1 phase), and suppress elongation of DNA replication (S phase). The chelation of iron seems to be one of the main modes of action of mimosine for cell cycle arrest. As an iron-chelating and cell cycle stopping agent, mimosine was tested in preclinical models of cancer, pulmonary fibrosis and iron overload.