oa South African Journal of Chemistry - Syntheses, protonation constants and antimicrobial activity of 2-substituted N-alkylimidazole derivatives : research article
|Article Title||Syntheses, protonation constants and antimicrobial activity of 2-substituted N-alkylimidazole derivatives : research article|
|© Publisher:||South African Chemical Institute (SACI)|
|Journal||South African Journal of Chemistry|
|Affiliations||1 Rhodes University, 2 Rhodes University, 3 Rhodes University, 4 Rhodes University, 5 Rhodes University, 6 Rhodes University, 7 Rhodes University, 8 Rhodes University and 9 Rhodes University|
|Publication Date||Jan 2012|
|Pages||231 - 238|
|Keyword(s)||Antimicrobial, N-alkylimidazoles and pKa effect|
A series of N-alkylimidazole-2-carboxylic acid, N-alkylimidazole-2-carboxaldehyde and N-alkylimidazole-2-methanol derivatives [alkyl = benzyl, methyl, ethyl, propyl, butyl, heptyl, octyl and decyl] have been synthesized and the protonation constants determined. The antimicrobial properties of the compounds were tested against Gram-negative (Escherichi coli), Gram-positive (Staphylococcus aureus & Bacillus subtilis subsp. spizizenii) bacterial strains and yeast (C. albicans). Both the disk diffusion and broth microdilution methods for testing the antimicrobial activity showed that N-alkylation of imidazole with longer alkyl chains and the substitution with low pKa group at 2-position resulted in enhanced antimicrobial activity. Particularly, the N-alkylimidazole-2-carboxylic acids exhibited the best antimicrobial activity due to the low pKa of the carboxylic acid moiety. Generally, all the N-alkylimidazole derivatives were most active against the Gram-positive bacteria [S. aureus (MIC = 5-160 µg mL-1) and B. subtilis subsp. spizizenii (5-20 µg mL-1)], with the latter more susceptible. All the compounds showed poor antimicrobial activity against both Gram-negative (E. coli, MIC = 0.15 to >2500 µg mL-1) bacteria and all the compounds were inactive against the yeast (Candida albicans).
Article metrics loading...