A Biochemical Screening Test for the Photosensitizing Potential of Drugs and Disinfectants

Abstract

A series of photosensitizers known to cause photodermatitis were tested with respect to photosensitizing properties. Irradiation of these sensitizers together with unsaturated fatty acids or amino acids showed that few of them can be transformed by most of the photosensitizers. SH groups can. however, be destroyed by most of the photosensitizers known in dermatological practice. At low photosensitizer-to-SH group ratios, GSSG is formed; at higher ratios, other transformations of GSH predominates. The reactivity of GSH with ninhydrin is decreased after irradiation with a photosensitizer. Glutathione seems to be a biomolecule that is suitably sensitive to photosensitized modification and thus suitable for evaluation of any photosensitizing activity that new drugs may have as an unwanted side effect. In Methods in Enzymology 11 (Edited by P. S. Colowich and N. 0. Kaplan) 127: pp. 722-725. Academic Press, New York. 161--170. Wiener Klin. Woch. 89, 177-184.

Lack of singlet oxygen formation by photoexcited promazine derivatives in aqueous and ethanolic solutions

“…This conclusion is supported by the fact that photooxidation of L-histidine, a well known 10 2 scavenger, does not occur when CPZ is used as photosensitizer (Schothorst et al 1979). The lack of 10 2 production is however in contradiction with previous proposals, which were based on reactions using either DABCO (1,4-diazabicyclo[2.2.2]octane; Davies et al 1976) or dimethylfuran (Moore 1977).…”

SPECTROSCOPIC STUDIES OF CUTANEOUS PHOTOSENSITIZING AGENTS–XII. SPIN TRAPPING STUDY OF THE FREE RADICALS GENERATED DURING THE PHOTOLYSIS OF PHOTO ALLERGENS BITHIONOL and FENTICHLOR

“…Aryl radicals are highly reactive chemical species which readily abstract hydrogen atoms from suitable donors (Li and Chignell, 1987b;van der Walt and Cahnman, 1982;Arvis et al, 1978). In vivo these radicals may be expected to initiate lipid peroxidation and oxidize glutathione (Schothorst, 1979). The secondary free radicals formed from macromolecules may react with the aryl radicals to form covalent complexes which could act as antigens and elicit an allergic response.…”