B. Lupanine
Biological Source It is obtained from the herb of Genista tinctoria L. (Fabaceae) (Dyer’s Broom).
Chemical Structure
(7α, 7aα, 14α, 14aβ)-Dodecahydro-7, 14-methano-2H, 11H-dipyridiol [1, 2-a: 1’, 2’-e] diazocin-11-one; (C15H24N2O].
Isolation The racemic and optical isomers of lupanine have been duly isolated from various species of Lupinus (Fabaceae/Leguminosae) as stated below:
(±)-Lupanine—from white lupins;
d-Lupanine—from blue lupins;
l-Lupanine—from the natural racemic form;
Characteristic Features The physical parameters of the above three forms of lupanine are given below:
dl-Lupanine: It is obtained as orthorhombic prisms obtained from acetone having mp 98-99°C; bp1.0 185-195°C; It is soluble in ethanol, ether, chloroform and water; and insoluble in petroleum ether.
d-Lupanine (Synonym: 2-Oxosparteine): It is obtained as syrup crystallizing difficultly in hygroscopic needles having mp 40-44°C; bp3 190-193°C; nD24 1.5444; [α]D25 +84o (C = 4.8 in ethanol). It is found to be freely soluble in water, ethanol, ether and chloroform.
l-Lupanine (Synonym: Hydrorhombinine): It is a viscous liquid having bp1.0 186-188°C; [α]D - 61o in acetone.
Identification Test Lupanine forms the corresponding lupanine hydrochloride dihydrate (C15H24N2O.HCl.2H2O) which is obtained as rhombic crystals from water having mp 127°C (dry).
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* Couch, J.F., J. Am. Chem. Soc., 56, 2434 (1934).
