亚麻苦苷, Linamarin

Linamarin is a glucoside of acetone cyanohydrin found in the leaves and roots of cassava, lima beans, and flax. It is thought to function in the transport of nitrogen from plant leaves to roots in young plants but also serves as a plant defense mechanism. Linamarin is converted to toxic hydrocyanic acid or prussic acid when it comes into contact with linamarase, an enzyme that is released when the cells of cassava roots are ruptured.

Linamarin, also known as phaseolunatin or manihotoxin, belongs to the class of organic compounds known as cyanogenic glycosides. These are glycosides in which the aglycone moiety contains a cyanide group. Linamarin exists as a solid, soluble (in water), and a very weakly acidic compound (based on its pKa). Within the cell, linamarin is primarily located in the cytoplasm. Linamarin can be biosynthesized from 2-hydroxy-2-methylpropanenitrile. Linamarin is a bitter tasting compound that can be found in a number of food items such as sesbania flower, yardlong bean, kiwi, and sugar apple. This makes linamarin a potential biomarker for the consumption of these food products. Linamarin is a potentially toxic compound.

Linamarin is a beta-D-glucoside. It derives from a 2-hydroxy-2-methylpropanenitrile.

Title: Linamarin

CAS Registry Number: 554-35-8

CAS Name: 2-(b-D-Glucopyranosyloxy)-2-methylpropanenitrile

Additional Names: phaseolunatin

Molecular Formula: C10H17NO6

Molecular Weight: 247.25

Percent Composition: C 48.58%, H 6.93%, N 5.66%, O 38.83%

Literature References: From the seed skins or embryos of flax: Jorissen, Hairs, Bull. Acad. Roy. Sci. Belg. [3] 21, 529 (1891); André et al., Compt. Rend. 231, 590 (1950); Lüdtke, Biochem. Z. 323, 428 (1953). Synthesis: Fischer, Anger, Ber. 52, 854 (1919). Biosynthesis in white clover: Butler, Butler, Nature 187, 780 (1960).

Properties: Bitter needles, mp 142-143°. [a]D18 -29°. Freely sol in water, cold alcohol, hot acetone; slightly in hot ethyl acetate, ether, benzene, chloroform. Practically insol in petr ether. Evolves HCN with linseed meal but not with emulsin.

Melting point: mp 142-143°

Optical Rotation: [a]D18 -29°

Derivative Type: Tetraacetate

Molecular Formula: C18H25NO10

Molecular Weight: 415.39

Percent Composition: C 52.05%, H 6.07%, N 3.37%, O 38.52%

Properties: Needles from alcohol, mp 140-141°. [a]D14 -10.8° (acetone). Sol in acetone, ethyl acetate, chloroform, glacial acetic acid, benzene, warm methanol and ethanol. Practically insol in petr ether.

Melting point: mp 140-141°

Optical Rotation: [a]D14 -10.8° (acetone)