Premium
SPECTROSCOPIC STUDIES OF CUTANEOUS PHOTOSENSITIZING AGENTS—II. SPIN TRAPPING OF PHOTOLYSIS PRODUCTS FROM SULFANILAMIDE AND 4‐AMINOBENZOIC ACID USING 5,5‐DIMETHYL‐1‐PYRROLINE‐1‐OXIDE
Author(s) -
Chignell Colin F.,
Kalyanaraman B.,
Sik Robert H.,
Mason Ronald P.
Publication year - 1981
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1981.tb08978.x
Subject(s) - sulfanilamide , chemistry , spin trapping , photodissociation , pyrroline , photochemistry , trapping , medicinal chemistry , organic chemistry , biochemistry , radical , ecology , biology
— The photodecomposition of sulfanilamide, 4‐aminobenzoic acid and related analogs in aqueous solution has been studied with the aid of spin traps 5,5‐dimethyl‐1‐pyrroline‐1‐oxide (DMPO) and CH 3 NO 2 as well as by direct electron spin resonance techniques. The NH 2 radical was trapped by DMPO during the photolysis of aqueous solutions of sulfanilamide with a Xe arc lamp. Studies with [ 15 N 1 ]‐sulfanilamide indicated that the NH 2 radical was generated by homolytic fission of the sulfur‐nitrogen bond. Under the same conditions DMPO trapped the H and SO − 3 radicals during photolysis of sulfanic acid. Direct photolysis of sulfanilamide, sulfanilic acid and Na 2 SO 3 in the absence of any spin trap yielded the SO − 3 radical. Photolysis of 4‐aminobenzoic acid at pH 7 gave the H radical which was trapped by DMPO. At low pH values OH and C 6 H 4 COOH radicals were generated during the photolysis of 4‐aminobenzoic acid. No e − aq were trapped by CH 3 NO 2 when acid (pH 4) and neutral aqueous solutions of sulfanilamide or 4‐aminobenzoic acid were photoirradiated. The mechanism of formation of known photoproducts from the free radicals generated by sulfanilamide and 4‐aminobenzoic acid during irradiation are discussed. The free radicals generated by these agents may play an important role in their phototoxic and photoallergic effects.