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Z. Naturforsch.
69c, 124 – 132
(2014)
doi:10.5560/ZNC.2013-0137
The Co-Occurrence of Two Pyridine Alkaloids, Mimosine and Trigonelline, in Leucaena leucocephala
1 Biotechnology Research Center and Department of Biotechnology, Toyama Prefectural University, Imizu, Toyama, 939-0398, Japan
2 Department of Biological Sciences, Graduate School of Humanities and Sciences, Ochanomizu University, Tokyo, 112-8610, Japan. E-mail:
ashihara.hiroshi@ocha.ac.jp
3 Iriomote Station, Tropical Biosphere Research Center, University of the Ryukyus, Okinawa, 907-1541, Japan
*Author for correspondence and reprint requests
Received August 23, 2013 / January 13, 2014 / published online April 25, 2014
Leucaena leucocephala is a nitrogen-fixing tropical leguminous tree that produces two pyridine alkaloids, i. e. mimosine [β-(3-hydroxy-4-pyridon-1-yl)-l-alanine] and trigonelline (1-methylpyridinium-3-carboxylate). Mimosine has been detected in leaves, flowers, pods, seeds, and roots, and it is one of the principal non-protein amino acids that occurs in all organs. Asparagine was the most abundant amino acid in flowers. The mimosine content varied from 3.3 μmol/g fresh weight (FW) in developing flowers to 171 μmol/g FW in mature seeds. Trigonelline was also detected in leaves, flowers, pods, and seeds, but not roots. The trigonelline content was lower than that of mimosine in all organs. It varied from 0.12 μmol/g FW in developing seeds to
2.6 μmol/g FW in mature seeds. [2-14C]Nicotinic acid supplied to the developing seeds was incorporated into trigonelline but not mimosine. This indicates that the pyridine and dihydroxypyridine structures of these two alkaloids are derived from distinct precursors. The physiological functions of mimosine and trigonelline are discussed briefly.
Key words: Leucaena leucocephala, Pyridine Metabolism, Nicotinic Acid Derivatives