Characterization of the transient intermediates generated from the photoexcitation of nabumetone: a comparison with naproxen.

The photochemical and photophysical properties of nabumetone (4-[6-methoxy-2-naphthyl]-2-butanone) were examined employing conventional and time-resolved spectroscopic techniques. The naphthalene-like nabumetone triplet is formed with 29% efficiency in acetonitrile. Singlet oxygen formation was also detected in this solvent with a phi delta value of 0.19. A naphthalene-like radical cation absorption, formed via biphotonic processes, was also detected. The reactivity of both the triplet and radical cation of nabumetone toward different substrates was examined. The photochemical properties of nabumetone are compared with those of naproxen, a structurally related acidic nonsteroidal anti-inflammatory drug. For these two anti-inflammatory agents, a type II photosensitization process is most likely responsible for their phototoxicity.