Bergapten

Bergapten is the most important psoralen responsible for phototoxicity in expressed citrus oils. The compound is strictly limited in cosmetics and is the basis for producing furocoumarin-free (FCF) bergamot.

Skin and photobiology. Bergapten is strongly phototoxic. It can increase UV-induced DNA damage, although in some settings it also protects.

Cardiovascular. Strong antiplatelet aggregation activity in vitro.

Reproductive. Pregnant female rats fed 1,250–2,500 ppm for 39–49 days had fewer implantation sites and pups per female, reduced uterine weight at the high dose, and dose-dependently reduced 17β-estradiol. Bergapten also induced hepatic CYP1A1 and UGT1A6. Dietary 1,250–2,500 ppm in male rats for 8 weeks reduced pituitary and prostate size, lowered sperm counts, and elevated testosterone.

Bergapten is also used pharmaceutically in PUVA therapy for psoriasis and vitiligo, under close medical supervision.

Bergapten induces CYP1A1 and is a potent CYP3A4 inhibitor. Induction of estrogen metabolism may explain the reproductive toxicity observed in female rats.

Bergapten is the scientific basis for the advice not to apply expressed bergamot before sun exposure. Bergamot FCF is specifically produced to remove furocoumarins and is safe for outdoor use.

The compound was historically used as a tanning agent in suntan products but is now strictly limited.