| Popis: |
Quaternary ammonium compounds (QACs) are amphiphilic molecules known for their broadspectrum antibacterial activity. Although they have potent biological potential, they are often highly toxic to living organisms and ecosystems. Recent studies show that the addition of polar groups results in soft QACs that are more susceptible to hydrolysis, and therefore less toxic. [1] The aim of this study was to synthesize the new soft 3-acetamidoquinuclidine (QAc) and 3- benzamidoquinuclidine (QBn) QACs, both of which contain a naturally-derived quinuclidine backbone. [2, 3] The quaternization reactions were carried out using suitable alkyl halide chains of different lengths (12, 14 and 16 C atoms). The antibacterial activity of the new compounds was tested against a panel of Gram- positive and Gram- negative bacteria. We found that the QACs of 3- benzamidoquinuclidine exhibited better antibacterial activity in both bacterial panels (MIC between 3.9 and 62.5 μM) than the QACs of 3- acetamidoquinuclidine, which were active only against Gram-positive bacteria (MIC between 7.8 and 62.5 μM). Because we suspected that the composition of the culture medium might affect the activity of the QACs, we additionally determined the activity in CA-MHB and DMEM media. The MIC values in the cation-adjusted medium, i.e., CA- MHB, decreased 1- to 10-fold, and in the DMEM medium decreased 10- to 20-fold compared with the initial MIC values determined in MHB. These results indicate that the addition of an amide group and the composition of the culture medium strongly influence the antibacterial activity of the synthesized soft QACs. |
