Photoactivity of bleomycin

The anticancer drug, bleomycin, has recently been shown to be light-sensitive by a number of research groups. This photosensitivity extends to its complexes with iron(II), copper(II), cobalt(III) and DNA. Nicking of DNA by photoactivated bleomycin occurs at lower concentrations than under dark conditions. Phototreatment of a bleomycin/dopamine beta-hydroxylase mixture leads to extensive irreversible inhibition of the enzyme. The implications of this drug's photoreactivity are discussed.