Dibasic esters of ortho-/meta-alkoxyphenylcarbamic acid containing 1-dipropylamino-3-piperidinopropan-1-yl and their antimicrobial activity

In Europe, the presence of microorganisms that have become resistant to antimicrobials as the most significant disease threat has remained. The aim of the current research was to screen the in vitro susceptibility of Staphylococcus aureus, Escherichia coli and Candida albicans to the series of dibasic esters of ortho-/meta-alkoxyphenylcarbamic acid previously known for their local anaesthetic effectiveness and to contribute for the structure - antimicrobial potency relationships study within that class of the compounds. The antimicrobial activity investigation involved determination of the minimum inhibitory concentration (MIC) by applying the microdilution method; quantitative screening was performed on a blood agar (S. aureus), Endo agar (E. coli) or on Sabouraud's agar (C. albicans). The activity against all the microorganisms tested was primarily influenced by the position of alkoxy side chain attached to lipophilic aromatic ring and by its length as well. Inspected meta-alkoxy substituted derivatives have shown higher efficiency against all chosen microorganisms than their ortho-alkoxy positional isomers. The most promising results were observed when investigating the activity of meta-alkoxy substituted molecules against E. coli with the estimated MICs in the range of 12-49 microg/ml. Furthermore, such potency was found to be quasi parabolically dependent on alkoxy chain length achieving a maximum for meta-hexyloxy derivative which has shown MIC= 12 microg/ml. Considered compound was also regarded as the most effective against S. aureus with MIC = 98 microg/ml. Evaluating the potency against C. albicans, it was revealed that no molecule within the tested set displayed MIC < 100 microg/ml.