Coumarins

The term "coumarins" refers to a group of naturally occurring derivatives of coumarinum, also known as coumarin, a colourless, burning tasting substance that gives off a sweet, spicy, hay-like odour. The derivatives of coumarin are present as methoxy or hydroxy compounds. As plant constituents they are usually present in the cell as glycosidic compounds (meliolotoside). If the cell is damaged or under enzymatic influence, the aglycans are split off, whereby the typical aromatic smell (woodruff, hay) develops.

Coumarin is the parent compound of more than 3000 natural derivatives. They are widely distributed in the plant world, for example Apiaceae, Fabaceae, Rutaceae, Solanaceae, Asteraceae. Furthermore in essential oils, such as cinnamon or peppermint oil. Derivatives of coumarinum such as phenprocoumon or dicumarol act as competitive inhibitors of the enzyme gamma-glutamylcarboxylase. They inhibit the synthesis of the prothrombin complex and thus have an anticoagulant effect (see coumarins systemic).

7-Hydroxycoumarin (Umbelliferon) is by far the most common natural coumarin derivative.

Furanocoumarins are tricyclic ring systems. 7,6 Furanocoumarins are called psoralenes and are of great medical importance (seePUVA).

Coumarin was first isolated in 1813 by A. Vogel from the seeds of the tonka tree (Spanish cumarú), a tree native to Guyana (Coumaruona odorata). The fruits have a coumarin content of about 2 to 3%.

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