Bergapten is a 5-methoxyfurocoumarin that is psoralen substituted by a methoxy group at position 5. Bergapten occurs naturally in plants and is one of the main non-volatile components of Bergamot essential oil. Psoralens extracted from Bergamot have photosensitizing effects on the skin and have been used in sunscreens in the past. But these substances have been found to be photocarcinogenic and were banned in sunscreen formulations. Today Bergapten is used in combination with UV light irradiation only in certain therapies to manage psoriasis and vitiligo. In addition, Bergapten can inhibit proliferation in the human hepatocellular carcinoma cell line.