is a natural toxin produced by several tree species of the Moraceae family such as the common fig (Ficus carica).
This plant is reported to be cultivated by humans in the Middle East from as far as the 9th century BCE. Psoralen is a chemical from the family of furanocoumarins. It is present in relatively high concentrations in the milky sap of leaves, which has also high concentrations of another furanocoumarin, bergapten.
Psolaren is the main active compound of fig tree essential oil widely used in Asian traditional medicine for thousands of years. It has shown positive effects in trials to fight diabetes, osteoporosis and skin problems. Psoralen has also been reported to be effective to fight proliferation of skin cancer and skin disorders such as psoriasis. However, psolaren is also proved to cause lethal mutagenic effects on eukaryotic cells. The mechanism of action is by intercalation into the DNA double strand, forming covalent bonds with the nucleic acids after absorption of UV radiation.
The effectivity of psoralen absorbing UV light is the reason why it was added to sunscreen, with the claim of increasing both sun tanning and sun protection. However, studies in the 90’s reported that the presence of psolaren in sunscreen was associated with a higher incidence of skin melanoma. Based on the results, the use of psolaren as tanning activator in sunscreen was banned in 1996.
CAS no: 66-97-7
Chemical formula: C11H6O3
- Ashwood-Smith, M. J., Poulton, G. A., Barker, M., & Mildenberger, M. (1980). 5-Methoxypsoralen, an ingredient in several suntan preparations, has lethal, mutagenic and clastogenic properties. Nature, 285(5764), 407-409.
- Autier, P., Doré, J. F., Schifflers, E., Cesarini, J. P., Bollaerts, A., Koelmel, K. F., ... & Joarlette, M. (1995). Melanoma and use of sunscreens: an Eortc case‐control study in Germany, Belgium and France. International journal of cancer, 61(6), 749-755.
- Averbeck, D., Dardalhon, M., & Magana-Schwencke, N. (1991). Mutagenic effects of psoralen-induced photoadducts and their repair in eukaryotic cells. In Photobiology (pp. 933-950). Springer, Boston, MA.
- Tang, D. Z., Yang, F., Yang, Z., Huang, J., Shi, Q., Chen, D., & Wang, Y. J. (2011). Psoralen stimulates osteoblast differentiation through activation of BMP signaling. Biochemical and biophysical research communications, 405(2), 256-261.
- Common fig fruits: https://en.wikipedia.org/wiki/Common_fig
- Molecular structure of Psoralen: https://en.wikipedia.org/wiki/Psoralen