The sensitizing capacity of coumarins (I).

10 coumarins used in perfumery, cosmetics and ointments, have been investigated by 2 different methods to determine their sensitizing capacity. Only 1 of the compounds, 4-methyl-esculetin, which serves as a sunscreen agent, was found to be a weak sensitizer. All other coumarins were negative. It is assumed that this dihydroxycoumarin becomes a sensitizer when it is enzymically oxidized to the corresponding orthoquinone in the skin.