The furanocoumarins, or furocoumarins, are a class of organic chemical compounds 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 (DMAPP) and 7-hydroxycoumarin (umbelliferone).
The chemical structure of furanocoumarins consists of a furan ring fused with coumarin. The furan may be fused in different ways producing several isomers. The compounds that form the core structure of the two most common isomers are psoralen and angelicin. Derivatives of these two core structures are referred to respectively as linear and angular furanocoumarins.
Many furanocoumarin compounds are toxic. The phytochemicals enter the nucleus of epithelial cells and form a bond with the DNA, which causes the cells to die. As a result, the skin is unable to protect itself from sunlight, which leads to phytophotodermatitis, a serious skin inflammation.
Furanocoumarins are produced by plants as a defense mechanism against various types of predators ranging from insects to mammals. The substances are found in the sap of plants such as the wild parsnip, the giant hogweed and related umbellifers. There are also reports of these chemicals in the species Dictamnus albus.
Furanocoumarins have other biological effects as well. For example, in humans, bergamottin and 6',7'-dihydroxybergamottin are responsible for the "grapefruit juice effect", in which these furanocoumarins affect certain P450 liver and gut enzymes, such as the inhibition of CYP3A4 which either activates or deactivates many drugs, thus leading to higher or lower levels in the bloodstream. Furanocoumarins have various effects which can specifically increase or decrease (depending on the drug) the blood levels of many pharmaceuticals in ways that can be life-threatening and so FDA approved drugs will include warnings for grapefruit.
- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "furanocoumarins". IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "furocoumarins".
- Berenbaum, May (May 14, 2010). "Furanocoumarins as potent chemical defenses".
- Kakar, SM; Paine, MF; Stewart, PW; Watkins, PB (2004). "6',7'-Dihydroxybergamottin contributes to the grapefruit juice effect". Clinical Pharmacology and Therapeutics. 75 (6): 569–579. doi:10.1016/j.clpt.2004.02.007. PMID 15179411.