Mimosine

Mimosine or leucenol is a toxic non-proteinogenic amino acid chemically similar to tyrosine. It occurs in some Mimosa spp. (including M. pudica) and all members of the closely related genus Leucaena. This compound, also known as leucenol, was first isolated from the seeds of Leucaena glauca Benth., and was later investigated by Adams and coworkers. Mimosine melts with decomposition. The hydrochloride salt melts at 174.5–175.0 °C with decomposition; the hydrobromide decomposes at 179.5 °C, and the hydroiodide decomposes at 183–183.5 °C. Mimosine only forms monobasic acids, but the methyl ester forms a dihydrochloride, C7H9O2N2(COOMe)•2 HCl•½ H2O, mp. 175–6 °C. In the final step in the biosynthesis of mimosine in Leucaena leucocephala, the enzyme L-mimosine synthase transfers a 2-amino-2-carboxyethyl group from O-acetylserine to 3-hydroxypyridin-4(1H)-one (1) with acetic acid (CH3CO2H) as a byproduct. Mimosine arrests dividing cells in the late G1 phase by inhibiting DNA replication initiation.