Chlorpromazine-sensitized photooxidation of squalene.

In connection with chlorpromazine-induced skin photosensitivity, chlorpromazine-sensitized photooxidation of squalene was studied in vitro. When squalene (in ethanolic solution or in an aqueous suspension) was irradiated with UV-A light in the presence of chlorpromazine, the yield of peroxidation products was greatly increased. Lines of evidence for the peroxidation were obtained by the iodometric determination and the thiobarbituric-acid method. Gas chromatography indicated that squalene was decomposed by the photosensitized reaction and the remaining amount was decreased exponentially with increasing fluence. The quenching effects of NaN3 and 2,5-dimethylfuran and the enhancing effect of D2O showed participation of singlet oxygen in the photosensitized reaction.