coumarin

Coumarin
IUPAC name	2H-chromen-2-one
Other names	1-benzopyran-2-one
Identifiers
CAS number	91-64-5 Y
PubChem	323
SMILES	C1=CC=C2C(=C1)C=CC(=O)O2
Properties
Molecular formula	C9H6O2
Molar mass	146.143
Density	0.935 g/cm³ (20 °C)
Melting point	71 °C
Boiling point	301 °C
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Coumarin is a chemical compound (specifically, a benzopyrone) found in many plants, notably in high concentration in the tonka bean (Dipteryx odorata), vanilla grass (Anthoxanthum odoratum), woodruff (Galium odoratum), mullein (Verbascum spp.), and sweet grass (Hierochloe odorata). It has a sweet scent, readily recognised as the scent of newly-mown hay, and has been used in perfumes since 1882. It has clinical medical value as the precursor for several anticoagulants, notably warfarin, and is used as a gain medium in some dye lasers.^[1][2][3]

The name comes from a French word, coumarou, for the tonka bean.

Synthesis

The biosynthesis of coumarin in plants is via hydroxylation, glycolysis and cyclization 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.

Biological function

Coumarin has appetite-suppressing properties, suggesting its widespread occurrence in plants, especially grasses, is because of its effect of reducing the impact of grazing animals.^{[citation needed]}

Derivatives

Some naturally occurring coumarin derivatives include umbelliferone (7-hydroxycoumarin), aesculetin (6,7-dihydroxycoumarin), herniarin (7-methoxycoumarin), psoralen and imperatorin. Coumarin and its derivatives are all considered phenylpropanoids.

Medical use

Coumarin has been used in the treatment of lymphedema.^[4]

Toxicity and use in foods, beverages, tobacco, and cosmetics

Coumarin is moderately toxic to the liver and kidneys, with an LD₅₀ of 275 mg/kg—low compared to related compounds. Although only somewhat dangerous to humans, coumarin is a potent rodenticide: rats and other rodents largely metabolize it to 3,4-coumarin epoxide, a toxic compound that can cause internal hemorrhage and death. Humans largely metabolize it to 7-hydroxycoumarin, a compound of lower toxicity. The German Federal Institute for Risk Assessment has established a tolerable daily intake of 0.1 mg coumarin per kg body weight, but also advises that, [if] this level is exceeded for a short time only, there is no threat to health.^[5] For example, a person weighing 135 lbs or about 61 kg would have a TDI of approximately 6.1 mg of coumarin.

European health agencies have warned against consuming high amounts of cassia bark, one of the four species of cinnamon, because of its coumarin content.^[6] According to the German Federal Institute for Risk Assessment, 1 kg of (cassia) cinnamon powder contains approximately 2100 to 4400 mg of coumarin.^[7] Powdered Cassia Cinnamon weighs 0.56 g/cc^[8]; therefore, 1 kg of Cassia Cinnamon powder is equal to 362.29 teaspoons (1000 g divided by 0.56 g/cc multiplied by 0.20288 tsp/cc). This means 1 teaspoon of cinnamon powder contains 5.8 to 12.1 mg of coumarin, which may be above the Tolerable Daily Intake for smaller individuals.^[7] However, it is important to note that the German Federal Institute for Risk Assessment only cautions against high daily intakes of foods containing coumarin. Chamomile, a common herbal tea, also contains coumarin.

Coumarin is often found in tobacco products and artificial vanilla substitutes, despite having been banned as a food additive in numerous countries since the mid-20th century. Coumarin was banned as a food additive in the United States in 1978. OSHA considers this compound to be only a lung-specific carcinogen, and "not classifiable as to its carcinogenicity to humans".^[9] Coumarin was banned as an adulterant in cigarettes by tobacco companies in 1997, but due to the lack of reporting requirements to the US Department of Health and Human Services it was still being used as a flavoring additive in pipe tobacco.^{[citation needed]} Coumarin is currently listed by the United States Food and Drug Administration (FDA) among "Substances Generally Prohibited From Direct Addition or Use as Human Food", according to 21 CFR 189.130,^[10][11] but some natural additives containing coumarin (such as Sweet Woodruff) are allowed "in alcoholic beverages only" (21 CFR 172.510).^[12] In Europe, such beverages are very popular, for example Maiwein (white wine with woodruff) and Żubrówka (vodka flavoured with bison grass).

Coumarin should be avoided by people with perfume allergy.^[13]

Related compounds and derivatives

Compounds derived from coumarin are also called "coumarins". Compounds within this coumarin family include:

• brodifacoum^[14][15]
• bromadiolone^[16]
• coumafuryl^[17]
• difenacoum^[18]
• auraptene
• ensaculin
• phenprocoumon (Marcoumar)
• Scopoletin can be isolated from the bark of Shorea pinanga^[19]
• warfarin

Several of the above compounds are used as anticoagulant drugs and/or as rodenticides.

Use as pesticides

Coumadins, dicoumerol derivatives of coumarin, are potent rodenticides because they block the synthesis of vitamin K, especially in rodents, giving it strong anticoagulatory and rodenticidal properties. Death occurs after a period of between several days to two weeks, usually from internal hemorrhaging.

Vitamin K is a true antidote for poisoning by coumadins such as bromadiolone. Treatment usually comprises a large dose of vitamin K given intravenously immediately, followed by doses in pill form for a period of at least two weeks, though usually three to four, afterwards. If caught early, prognosis is good, even when large amounts are ingested.^{[citation needed]}

References

External links

• More info about coumarin
• Coumarin in tobacco
• More info about Coumane(TM)
• Coumarin as an ingredient of perfume.
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