Spectroscopic studies of cutaneous photo sensitizing agents 4. the protolysis of benoxaprofen an anti inflammatory drug with photo toxic properties

Reszka, K.; Chignell, C. F.

Benoxaprofen [2-(4-chlorophenyl)-.alpha.-methyl-5-benzoxazole acetic acid] is an antiinflammatory drug than causes acute phototoxicity in many patients. Photolysis studies in organic solvents (ethanol, benzene, dimethylsulfoxide) showed that benoxaprofen underwent both type I and type II reactions. Irradiation of an anerobic solution of benoxaprofen in ethanol resulted in hydrogen abstraction from the solvent to yield hydroxyethyl and ethoxy radicals. In the presence of O2 superoxide, singlet oxygen and hydroxyethyl radicals were detected. Photolysis of benoxaprofen in air-saturated benzene or dimethylsulfoxide gave superoxide. Under anerobic conditions the drug yielded a carbon-centered radical in benzene that could not be identified. Both O2-dependent and O2-independent processes may be important in the phototoxic reactions of benoxaprofen.