On the structure of leucaenine (leucaenol) from leucaena glauca bentham

From the seeds of Leucaena glauca B, obtained from the Netherlands Indies, we isolated leucaenine which, under the name leucaenol, was first described in 1937 by Mascre, who determined for this compound the empirical formula C4H5O2N. We obtained about 16 g of pure leucaenine (melting point 226°–227° with decomposition) from 1 kg of seeds. From an electrometrical titration the molecular formula of the substance is found to be C8H10O4N2; leucaenine is an α-amino acid in the molecule of which a pyridine ring substituted by hydroxyl occurs. By the action of dimethyl sulphate and alkali on leucaenine we obtained a compound C7H11O3N (I) which could be converted into a N-methylhydroxypyridone having the composition C6H7O2N (II). This compound is not identical with N-methyl-6-hydroxypyridone-2 or with N-methyl-3-hydroxypyridone-2, which hitherto unknown pyridones were obtained by synthesis, and it is likewise not identical with the N-methyl-4-hydroxypyridone-2 (or N-methyl-2-hydroxypyridone-4) described by Spath. To the compound C6H7O2N therefore the structure of an N-methyl-3-hydroxypyridone-4 or of an N-methyl-5-hydroxypyridone-2 must be assigned; for the present we consider the first structure mentioned the more probable. Leucaenine itself must be considered as a β-[hydroxypyridyl-oxy] -α-aminopropionic acid; the positions at which the hydroxyl group and the serine radical are substituted in the pyridine nucleus have not yet been determined, although it follows from our investigation that several positions are impossible. The most probable formula for leucaenine is in our opinion: β-[3-(4-hydroxypyridyl)-oxy]-α-aminopropionic acid. Since the compound isolated by us must therefore be classed among the naturally occurring amino acids we propose to call this substance leucaenine. The substance mimosine isolated by Renz and by Nienburg and Taubock from the leaf stems of Mimosa pudica L. and of Leucaena glauca B is very probably identical with leucaenine. From experiments on animals it was found that the administering of leucaenine or of seeds of Leucaena glauca B to rats or mice did not cause the hair to fall out. This result is not in agreement with several statements in the literature, according to which larger mammals, such as horses and donkeys, showed loss of hair after being fed on seeds or leaves of the plant.