Observations on the Anticatalase Activity of Sulfanilamide and Related Compounds before and after Ultraviolet Irradiation.--MARJORIE P. BENOY. Sulfanilamide and a number of closely related compounds were found by Main, Shinn and Mellon (Proc. Soc. Exptl. Biol. Med., 39, 272, 1938) to have on catalase a definite inhibitory effect which was increased by preliminary exposure of the compounds in solution to ultraviolet light. Particular significance was attached by them to the intrinsic, catalase-depressing power of the unirradiated compounds and a possible connection between it and therapeutic potency was suggested. Subsequently these workers (Shinn, Main, and Mellon, Ibid., 42, 736, 1939; Locke and Mellon, Science, 9o, 231, 1939) postulated that p-hydroxamino benzenesulfonamide was the compound developed by ultraviolet light which was responsible for the in vitro enzymeinhibiting action of the irradiated solutions.
The observations made in this laboratory on the native and ultraviolet light-induced, anticatalase activity of sulfanilamide and related compounds, and the conclusions derived therefrom, are somewhat at variance with those of the authors mentioned above.
Materials.--Catalase was prepared from rabbit red blood corpuscles by the method of Sevag and Maiweg (Biochem. Z., 288, 4 I, 1936 ).
Aromatic Chemicals were in general obtained on the market and used without further purification. Sulfamethylthiazol (2-sulfanilamide-4-methyl thiazqle) was courteously supplied by the Maltbie Chemical Company. p-Nitrobenzenesulfonamide was prepared by Mr. Harry Winter of this laboratory from p-nitrobenzenesulfonylchloride made by an adaptation of the Loudon-Shulman method (J. Chem. Soc., 1938 , p. 1618). Benzene "A" was prepared from Mallinckrodt's "benzol pure" by the usual procedure for the removal of thiophene, followed by fractional distillation. Benzene "B" 4o2