Psoralen · Constituent

Chemical info / 化学情報

CAS number CAS

66-97-7

Molecular formula

C₁₁H₆O₃

Molecular weight

186.16 g/mol

Aroma

Essentially odorless, a hidden phototoxic constituent in citrus and umbelliferous oils.

Safety / 安全性

Phototoxic · Mutagenic · IFRA + EU prohibited

Psoralen is one of a group of furanocoumarins causing significant photosensitization and phototoxicity in animals and humans. The European Union and SCCP impose strict limits in cosmetics.

Phototoxicity. In combination with UVA, psoralen causes DNA damage and persistent skin darkening. It is the constituent that makes rue, bitter orange and non-FCF bergamot oils highly phototoxic.

Mutagenicity. Psoralen was positive in the SOS chromotest and genotoxic in human lymphocytes and HepG2 hepatoma cells. It was mutagenic in HPRT assay and photogenotoxic in a micronucleus assay above 5 µg/mL.

CYP interaction. Psoralen is a potent inhibitor of microsomal CYP3A with an IC50 of 5.1 µM. It inhibits CYP3A4 more weakly with IC50 of 116 to 257 µM in human liver.

Usage guidelines / 使用基準

Concern level

High · phototoxic and mutagenic

EU SCCNFP limit

1 ppm for furocoumarin-like substances in all cosmetics

Oils with high content

Rue 0.015 percent · Angelica root 0.011 percent

Found in essential oils / 含有精油

Principal sources
Rue	0.015 %
Angelica root	0.0112 %
Taget	0.011 %
Orange (bitter)	0.007 %
Bergamot	0 – 0.0026 %

Notes / 注記

Psoralen is used medically alongside UVA in PUVA therapy for psoriasis and vitiligo under strict supervision. In cosmetics and fragrance, psoralen and related furanocoumarins are limited to 1 ppm.