Abstract
In a previous publication 1 the authors demonstrated that solutions of sulfanilamide and certain related compounds were endowed with antieatalase activity following irradiation with ultraviolet light. It was suggested in a subsequent paper 2 that this activity might result from the formation of either the p-hydroxylamino derivative or free hydroxylamine in the irradiated solutions. Taking hydroxylamine as a standard, it was calculated that the activity found could be explained by the conversion of about 2% of the sulfanilamide in an irradiated 8 mg % solution into the active compound. At that time no evidence was available to show that the assumed derivatives were actually formed under the conditions described. With a method recently developed by Rosenthal and Bauer, 3 it has been possible to demonstrate that solutions of sulfanilamide upon ultraviolet irradiation yield appreciable amounts of a substance which reacts as the p-hydroxylamino derivative.
Rosenthal and Bauer's method for the estimation of the p-hydroxylamino derivative in the presence of the free amine is based on the fact that in a mixture of the two substances, the amine can be acetylated by acetic anhydride and thus prevented from participating in the diazotization and coupling. The hydroxylamino form is not so affected and can thus be determined colorimetrically. As standards Rosenthal has recommended either p-hydroxylamino-benzene-sulfonamide or p-hydroxylaminobenzoic acid. We have chosen to use the benzoic acid.∗ Analyses were carried out precisely as in the specifications of Rosenthal and Bauer. The compounds were examined in simple, neutral aqueous solutions and in this respect were parallel to the standards. Complications arising from other organic materials which might be present in urine were, of course, not encountered.
Sulfanilamide was irradiated by exposing a thin layer of an aqueous solution for 1 min at a distance of 3 in. from an ultraviolet lamp.
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