Furanocoumarins, or furocoumarins, are a class of organic chemical compounds

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

 produced by a variety of plants. They are biosynthesized partly through the phenylpropanoid pathway and the mevalonate pathway, which is biosynthesized by a coupling of dimethylallyl pyrophosphate

Dimethylallyl pyrophosphate

Dimethylallyl pyrophosphate is an intermediate product of both mevalonic acid pathway and DOXP/MEP pathway. It is an isomer of isopentenyl pyrophosphate and exists in virtually all life forms...

 (DMAPP) and 7-hydroxycoumarin

Umbelliferone

Umbelliferone, also known as 7-hydroxycoumarin, hydrangine, skimmetine, and beta-umbelliferone, is a widespread natural product of the coumarin family. It occurs in many familiar plants from the Apiaceae family such as carrot, coriander and garden angelica, as well plants from other families such...

 (umbelliferone).

The chemical structure of furanocoumarins consists of a furan

Furan

Furan is a heterocyclic organic compound, consisting of a five-membered aromatic ring with four carbon atoms and one oxygen. The class of compounds containing such rings are also referred to as furans....

 ring fused with coumarin

Coumarin

Coumarin is a fragrant chemical compound in the benzopyrone chemical class, found in many plants, notably in high concentration in the tonka bean , vanilla grass , sweet woodruff , mullein , sweet grass , cassia cinnamon and sweet clover...

. The furan may be fused in different ways producing several isomer

Isomer

In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...

s. The compounds that form the core structure of the two most common isomers are psoralen

Psoralen

Psoralen is the parent compound in a family of natural products known as furocoumarins. It is structurally related to coumarin by the addition of a fused furan ring, and may be considered as a derivative of umbelliferone...

 and angelicin

Angelicin

Angelicin is a furanocoumarin. It can be found in Bituminaria bituminosa. It is present in the list of IARC Group 3 carcinogens ....

. Derivatives of these two core structures are referred to respectively as linear and angular furanocoumarins.

Many furanocoumarins are toxic and are produced by plants as a defense mechanism against various types of predators ranging from insect

Insect

Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...

s to mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s. This class of phytochemical

Phytochemical

Phytochemicals are biologically active chemical compounds that occur naturally in plants . Phytochemicals are the molecules responsible for the color and organoleptic properties . For example, the deep purple color of blueberries and the smell of garlic...

 is responsible for the phytophotodermatitis

Phytophotodermatitis

Phytophotodermatitis is a chemical reaction which makes skin hypersensitive to ultraviolet light. It is frequently mistaken for hereditary conditions such as atopic dermatitis or chemical burns, but it is caused by contact with the photosensitizing compounds found naturally in some plants and...

 seen in exposure to the juices of the wild parsnip

Parsnip

The parsnip is a root vegetable related to the carrot. Parsnips resemble carrots, but are paler than most carrots and have a sweeter taste, especially when cooked. The buttery, slightly spicy, sweet flavor of cooked mature parsnips is reminiscent of butterscotch, honey, and subtle cardamom...

 and the Giant Hogweed

Giant Hogweed

Heracleum mantegazzianum, commonly known as giant hogweed, cartwheel-flower, wild parsnip, wild rhubarb, giant cow parsnip, or giant cow parsley, is a plant in the family Apiaceae. It typically grows to heights of , sometimes reaching...

.

Furanocoumarins have other biological effects as well. For example, in humans, bergamottin

Bergamottin

Bergamottin is a natural furanocoumarin found principally in grapefruit juice. It is also found in the oil of bergamot, from which it was first isolated and from which its name is derived. To a lesser extent, bergamottin is also present in the essential oils of other citrus fruits...

 and dihydroxybergamottin are responsible for the "grapefruit juice effect", in which these furanocoumarins affect the metabolism of certain drugs.