Bioactivity and morphological changes of bacterial cells after exposure to 3-(p-chlorophenyl)thio citronellal

Abstract

In order to investigate the use of semi-synthetic antimicrobial compounds, the objective of this study was to evaluate the 3-(p-chlorophenyl)thio citronellal, a novel compound that is derived from the essential oil of Cymbopogon citratus, against spoilage and pathogenic bacteria in food. This study also evaluated the possible mechanisms of action and cellular targets. Qualitative and quantitative tests and scanning electron microscopy were used to compare 3-(p-chlorophenyl)thio citronellal with citral and (R)-citronellal. It was observed that 3-(p-chlorophenyl)thio citronellal is a potent antimicrobial agent with bactericidal activity against different pathogenic and spoilage bacteria, of which the Gram-positive species were the most sensitive. The minimal inhibitory concentration for 3-(p-chlorophenyl)thio citronellal was approximately 100 times lower than that of citral, and this was corroborated by the kinetic curve of action, demonstrating that cell death was faster when the bacterial cells were treated with 3-(p-chlorophenyl)thio citronellal. This finding showed that the addition of thiol enhances the bioactivity of citral. In vitro testing showed that the compound does not show toxicity. The SEM images showed cell damage with the formation of pores in the cell wall and membrane, which are possibly the cellular targets of the compound.