The sensitizing capacity of coumarins (II)

5 coumarins used in perfumery, cosmetics, therapeutic ointments or occurring naturally were investigated by Freund's complete adjuvant technique (FCAT) in guinea pigs to determine their contact sensitizing potency. 4-Methylesculetin was also studied. Esculetin, dihydrocoumarin and daphnetin were found to be moderate to strong sensitizers, while fraxetin was nearly and 7-methylcoumarin completely inactive. The results corroborate the hypothetical view that only those coumarins having a catecholic disubstitution in the benzene ring, e.g., esculetin, 4-methylesculetin, daphnetin, can become sensitizers on the basis that they are capable of forming ortho-quinones under oxidizing conditions.