Furanocoumarins

Tricyclic ring systems, whereby the furan ring is either linearly or angularly linked to the coumarin.

The linear 7,6-furanocoumarins are called psoralens. They are photosensitizing, which is the basis of PUVA therapy with 8-methoxypsoralen (see PUVA).

In dermatology, the furanocoumarins psoralen, bergapten, angelicin, xanthotoxin and coumarin play a major role.

The most important representatives of the angular 7,8-furanocoumarins are pimpinellin (see Pimpinellae Radix below) and angelicin, which can be found in Apiaceae, Rutaceae and Fabaceae. The highly toxic and carcinogenic mycotoxins found in certain molds (especially Aspergillus flavus), the aflatoxins, also have furanocoumarin structures.

Furanocoumarins are found in the following European plants:

Lime, lemon, bitter orange, bergamot, white diptam, garden rue, chervil, giant hogweed, hogweed, celery, parsnip, fennel, dill, hogweed, carrot, carrot cartilage, angelica, fig tree, Yarrow, field bindweed, agrimony, goosefoot, lovage(Levistici radix), fig, masterwort, parsley, hemlock, hogweed, giant hogweed, meadow chervil, grapefruit, rue.

Recent studies indicate that the furanocoumarins contained in citrus may increase the risk of non-melanocytic skin cancer due to phototoxic/sensitizing effects associated with UV radiation.

1. Almutawa F et al. (2013) Systematic review of UV-based therapy for psoriasis. Am J Clin Dermatol 14:87-109.
2. Atzmony L et al. (2016) Treatments for Cutaneous Lichen Planus: A Systematic Review and Meta-Analysis. Am J Clin Dermatol 17:11-22.
3. Zic JA (2015) Extracorporeal Photopheresis in the Treatment of Mycosis Fungoides and Sézary Syndrome. Dermatol Clin 33:765-776.
4. Sakaki JR et al. (2021) Citrus Consumption and the Risk of Non-Melanoma Skin Cancer in the Women's Health Initiative. Cancers (Basel). 30;:2173
5. Montag A (2023) Plants and skin. Springer-Verlag Ltd. S. 229-243