engleski

A membrane active alkyl-quinuclidines as new potential antimicrobial agents

Quinuclidine is a bicyclic alkaloid isolated from the bark of a cinchona tree. Quinuclidine and its better- known counterpart, quinine, have widely been used in traditional medicine as a remedy for fever, arrhythmia and malaria. Due to their enormous medicinal and pharmacological potential, these compounds have for a long time been an inspiration to organic chemists for the development of new drugs. As a result, a number of quinuclidine based drugs have been developed, some of which are now in clinical use as anticholinergic and neurotropic medicines. Here we present a new class of quinuclidine derivatives as potential antimicrobial candidates. These compounds, bearing different alkyl chain lengths were screened for their antimicrobial potential against several representative Gram- positive and -negative bacteria. The MIC and MBC values were determined for clinical isolates and the ATCC bacterial strains. The results show a positive correlation between antimicrobial activity and an alkyl chain length suggesting that alkyl chains are an important part of the structure that play a role in bioactivity. Moreover, it has been shown that our compounds display a much better antimicrobial activity toward Gram-positive strains. Therefore, an atomic force microscopy (AFM) was performed on S. aureus. These images revealed an enhanced secretion of the extracellular polymeric substances (EPS) and disruption of the bacterial cell wall upon treatment with concentration as low as 4 μg/mL. The extent of the cell membrane damage by flow cytometry and the effect on human cell lines are currently in progress.

quaternary ammonium salts, antimicrobial activity, cytotoxicity

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