p-Aminophenylketone als Antagonisten der p-Aminobenzoesäure

Abstract

P-Amino-benzoic acid is essential for the growth of Streptobacterium plantarum, the optimal conc. being 1:1010-1:1011 in the nutrient soln. It is suggested that the bactericidal action of the sulfonamides is due to the fact that they disturb the equilibrium: Apoenzyme + p-aminobenzoic acid [image] holo-enzyme. The symplex apoenzyme + sulfonamide is inactive as an enzyme. The nutrient soln. used in investigating the effect of various compounds on the growth of Streptobacterium plantarum contains glucose, salts, 11 amino acids, thiamine, pyridoxine, niacin, adenine and casein. (Kuhn and Wieland, Ber. deutsch, chem. Ges., 73: 965, 1940.) The nutrient soln. is placed in test tubes which are then inoculated with 3.107 cells and the compounds to be tested added. The tubes are kept at 30[degree] for 16 hrs. Growth is detd. by measuring the extinction of diluted solns. in the Pulfrich photometer. Sulfathiazole is very active in preventing growth, while sulfanilic acid derivatives whose amino group in the 4-position is substituted are inactive. Diaminodi-phenyl sulfone is more active than sulfathiazole, and its digalactoside, tibatin, also has considerable activity. All these compounds are inactivated if sufficient amts. of p-aminobenzoic acid are added to the tubes. For example, 2500 more times sulfanilamide are needed to prevent the growth of the bacteria when p-aminobenzoic acid is present. With Str. plantarum in vitro, p-aminophenyl ketones are also antagonistic to p-aminobenzoic acid, p p[image]-diamino-benzophenone being the most active. The latter compound also shows much antagonistic activity in infected mice. An antagonism between [beta]-acetylpyridine and niacin is not demonstrated.