[Organic ammonium salts. XLI. Preparation, aggregation properties and antimicrobial activity of N-[2-(10-undecenoyloxy)ethyl]-N,N,N-alkyldimethylammonium bromides].

The paper describes the preparation of 7 novel organic ammonium salts of N-[2-(10-undecenoyloxy)ethyl]-N,N,N-alkyl-dimethylammonium bromides, in which the alkyl chain was gradually lengthened from ethyl to tetradecyl, constantly keeping the other groups (10-undecenoyloxyethyl and methyl) bound to the ammonium nitrogen. In the paper the antimicrobial effect of the prepared ammonium salts and the aggregative properties of their aqueous solutions were studied. The aggregative properties are expressed by the values of the critical concentration of the micelles formation, which were determined tensiometrically and conductometrically. The antimicrobial activity expressed by the minimal inhibition concentration in dependence on the prolongation of the alkyl chain was determined by the dilution test on the strains Staphylococcus aureus, Escherichia coli and Candida albicans. As follows from the table, all ammonium salts prepared were active in this respect, the most effective ones possessing 6, 8 and 10 carbon atoms in the alkyl chain. They were more effective than the standard Ajatin to all strains of the microorganisms tested. The antimicrobial effect decreased with the increasing length of the alkyl chain. Also the structure--activity relationship was quantified by the QSAR analysis methods using two procedures: the dependence log ck vs. m was linear and the dependence log (1/MIC) vs. m and log (1/MIC) vs. log ck were nonlinear. The calculated coefficients of regression equations and statistical evaluation of dependences are shown in Table 4.(ABSTRACT TRUNCATED AT 250 WORDS)