Furocoumarins

Furocoumarins (also furanocoumarins ) are often found in umbellifers such as hogweed ( giant hogweed , meadow hogweed ) and medicinal angelica , as well as in rhombus plants such as citrus plants (including bergamot , lemon , lime , grapefruit , bitter orange etc.) and in a number of other plants . Furocoumarins belong to the secondary plant substances and serve as phytoalexins (a type of defense substance).

properties

In the basic structure of the furocoumarins, coumarin is fused with a furan ring . Well-known furocoumarins are psoralen , bergapten and xanthotoxin . Chalepensin (xylotensin) was also found in the diamond species Ruta chalepensis .

Coumarin

Psoralen

Angelicin

Like most α, β-unsaturated carbonyl compounds, furocoumarins are very reactive. Furocoumarins are photoactivated when exposed to sunlight ( UVA and UVB radiation). A prominent example is the poisonous juice of the giant hogweed (Hercules shrub). The furocoumarins it contains damage the human organism in two ways:

• Photosensitizing / phototoxic : If furocoumarins get on the skin and are then exposed to sunlight (UV radiation), symptoms similar to burns occur depending on the severity(reddening of the skin, swelling, blistering, lesions, photopigmentation, scarring). See also berloque dermatitis , photodermatitis .
• Carcinogenic : Furocoumarins form covalent bonds with the pyrimidine bases of the DNA under the action of UV, thus irreversibly linking the DNA double strands with one another ( DNA crosslinking ) and thus have a carcinogenic effect.

In medicine, furocoumarins such as bergapten , trioxsalen , xanthotoxin or trimethylpsoralen are used to treat psoriasis as part of phototherapy and photochemotherapy.

Overview

Psoralen type
image
Surname	Psoralen	Bergapten	Xanthotoxin	Isopimpinellin	Empress
R 1	H	OCH 3	H	OCH 3	H
R 2	H	H	OCH 3	OCH 3	O-CH 2 -CH = C (CH 3 ) 2
CAS number	66-97-7	484-20-8	298-81-7	482-27-9	482-44-0
PubChem	6199	2355	4114	68079	10212
Molecular formula	C 11 H 6 O 3	C 12 H 8 O 4	C 12 H 8 O 4	C 13 H 10 O 5	C 16 H 14 O 4
Molar mass	186.16 g mol −1	216.19 g mol −1	216.19 g mol −1	246.21 g mol −1	270.28 g mol −1

Angelicin type
image
Surname	Angelicin	Pimpinellin	Isobergapten	Sphondin
R 1	H	OCH 3	H	OCH 3
R 2	H	OCH 3	OCH 3	H
CAS number	523-50-2	131-12-4	482-48-4	483-66-9
PubChem	10658	4825	68082	108104
Molecular formula	C 11 H 6 O 3	C 13 H 10 O 5	C 12 H 8 O 4	C 12 H 8 O 4
Molar mass	186.16 g mol −1	246.21 g mol −1	216.19 g mol −1	216.19 g mol −1

Occurrence in nature (selection)

• 

  Grapefruit

• 

  orange

• 

  lemon

• 

  Medicinal angelica ( Angelica archangelica )

• 

  Giant hogweed ( Heracleum mantegazzianum )

• 

  Meadow hogweed ( Heracleum sphondylium )

Individual evidence

1. ↑ RM Brooker, JN Eble, NA Starkovsky: Chalepensin, chalepin and chalepin acetate, three novel furocoumarins from Ruta chalepensis. In: Lloydia. Volume 30, 1967, p. 73.
2. ↑ furanocoumarins as potent chemical defenses .
3. ↑ ^{a b} Jeannette Aryee-Boi: shower PUVA: An innovative method of local PUVA therapy Clinical and pharmacokinetic results in psoriasis vulgaris. Inaugural dissertation at the Free University of Berlin, 2002.
4. ↑ Oskar Schimmer: The mutagenic and carcinogenic potency of furocoumarins. In: Pharmacy in our time. Volume 10, No. 1, 1981, pp. 18-28.
5. ↑ Eberhart Teuscher: Biogenic poisons. 1987, p. 233.
6. ↑ Andreas Herde: Investigation of the coumarin pattern in fruits of selected Apiaceae. (PDF 2.3 MB) Dissertation University of Hamburg, 2005, p. 29 f.
7. ↑ Entry on furocoumarins. In: Römpp Online . Georg Thieme Verlag, accessed on May 19, 2015.