Photosensitivity of DNA-bound 7,12-dimethylbenz(alpha)anthracene.

Structural information about the products formed when 7,12-dimethylbenz(alpha)anthracene (DMBA) is bound to DNA in mammalian cell cultures has been sought through studies of the photosensitivities of these products and of various model compounds. Under conditions of light exposure in which the DNA-DMBA products were highly photosensitive, 8,9,10,11-tetrahydro-DMBA and 5,6-dihydro-DMBA were stable, whereas 9,10-dimethyl-anthracene and DMBA itself were highly photosensitive. This indicates that in the binding reaction with DNA, DMBA retains either the aromatic benz(alpha)anthracene nucleus or is metabolically activated in the 1,2,3,4-ring.