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Chapter 25,389

Researches on sulphanilamide, para-amino benzoic acid and their derivatives III. Ultraviolet absorption spectra and potentiometric titations. IV. The behaviour of sulphanilamide, p-amino-benzoic acid and of their derivatives with respect to the mercury/solution interface and to lecithin and protein monolayers. V. On the mechanism of the action of sul-phonamides and of p-amino-benzoic acid, with remarks on the action of ergons and anti-ergons in general

Havinga, E.; Veldstra, H.

Rec Trav Chim Pays Bas 66(5): 257-299

1947


Accession: 025388551

III. U.-v. absorption spectra were detd. and electrometric titrations carried out on o-, m-, and p-aminobenzoic acids, sulfanilic acid, sulfanilamide, sulfamylon, Percoccide (sulfa-4-methylpyrimidine) (spectrum only), sulfapyridine, sulfathiazole, 2-(sulfamethyl)-pyridine (spectrum only), 5-sulfatetrazole (spectrum only), p-amino -phenylacetic acid (titration only), and p-(aminomethyl)-benzoic acid (titration only) to det. the mode of action of sulfonamide and p-aminobenzoic acid. Sulfamylon and p-aminomethyl-benzoic acid stand out as having a separate position in relation to the others. IV. The same compounds with p-aminobenzoyl-1-glutamic acid, p-aminobenzoyl-d-glutamic acid,p-amino-benzoyl-1-aspartic acid, sulfanilyl guanidine, p-aminophenyl-acetic acid, l-aminonaphthalene-4-carboxylic acid, naphthio-namide, naphthionylaminopyridine and naphthionylaminomethyl-pyrimidine were polarographically investigated. From these data it appears improbable that p-aminobenzoic acid takes part on a redox system. In the case of the che motherapeutical-ly active sulfonamides the degree of activity runs parallel to their boundary activity. Sulfamylon again assumes a position different from the others. From results of studies on action on lipoid films,_p-aminobenzoic acid and the sulfonamides probably do not influence the permeability of bacterial membranes. V. The action of p-aminobenzoic acid or derivatives as a prosthetic group of an oxidation-reduction enzyme is considered to be improbable. Its function as a permeability regulator can with fair probability also be excluded. The hypothesis that p-aminobenzoic acts as a regulator of division is considered. p-Aminobenzoic acid may exert an influence on the synthesis of nucleoproteins or interact with these compounds which are essential in the division process. Data in the literature indicate that sulfonamides interfere with the division of mechanism rather than growth. p-Aminobenzoic acid and some other important ergons are still active at concentrations of 10-10 -10-12 m. At such a high dilution, the time necessary for the molecules to reach their place of action may approximate the time in which pysiological processes take place, and therefore may become a limiting factor. For 10-10 molar solns., a value of 1-100 mins. can be calculated, this being of the same order of magnitude as the time necessary for cell division of bacteria in rapid growth. The time of adsorption of ergons and anti-ergons (competitive factors) at the place of action-is very difficult to evaluate, as it proves to vary widely with small variations of the adsorption energy and therefore with seemingly small differences of structure. The feature may offer a clue for a better understanding of the difference in activity and relative specificity of many ergons. For molecules like p-aminobenzoic acid and the sulfonamides and adsorption time varying between 1 and 10-5 secs. is found to be proper approximation, consistent also with the hypothesis that at a concn. of 10-10-5 molar the simple sulfonamides are effective by competitively blocking the receptor for p-aminobenzoic acid. It is argued that competitive factors will be active only at higher concns. than the ergon they compete with. For ergons active at still higher dilutions (up to 10-20) a possible mechanism of guidance to their receptors along a cell surface is suggested.

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