Coumarin is a chemical compound found in many plants, notably in high concentration in the tonka bean, woodruff, and bison grass. It has a sweet scent, readily recognised as the scent of newly-mown hay. It has clinical value as the precursor for several anticoagulants, notably warfarin. It is also used as a gain medium in some dye lasers.
Synthesis
The
biosynthesis of coumarin in plants is via hydroxylation,
glycolysis and cyclisation of
cinnamic acid. Coumarin can be prepared in a laboratory in a
Perkin reaction between
salicylaldehyde and
acetic anhydride.
The Pechmann condensation provides another synthesis of coumarin and its derivatives.
Derivatives
Some naturally occurring coumarin derivatives include
umbelliferone (7-hydroxycoumarin),
herniarin (7-methoxycoumarin),
psoralen and
imperatorin.
Coumarin toxicity
Coumarin is often found in
tobacco products and artificial
vanilla substitutes, though it has been banned as a food additive in numerous countries since the mid-
20th century because it is moderately toxic to the liver and kidneys, with an
LD50 of 275 mg/kg - low compared to related compounds.
OSHA does not consider this compound to be carcinogenic with the exception of being a lung-specific carcinogen. Coumarin was banned as an adulterant by tobacco companies in 1997 but due to the lack of reporting requirements for pipe tobacco to the US
Department of Health and Human Services it was still being used as a flavoring additive in pipe tobacco. Coumarin was banned as a food additive in the United States in 1940, however it was still used in tobacco until 1997. Coumarin is on the
Food and Drug Administration's (FDA)
Generally Recognized as Safe (GRAS) list as an additive to
alcoholic beverages, most notably as an additive to white wines flavored with woodruff, a beverage popular in Germany known as
Maiwein. Concerns of coumarin damage to the kidneys and liver may to some extent be associated with coumarin derivatives, many of which are more toxic.
External links
lactones | Fluorescent dyes | Phenylpropanoids
Kumarin | Cumarin | Coumarine | Coumarine | クマリン | Kumaryna