Atividade antimicrobiana e o efeito do 3-(p-clorofenil)tio citronelal em bactérias patogênicas e deteriorantes com importância em alimentos.

Abstract

The objective of this study was to evaluate the antimicrobial potential of the compound 3-(pchlorophenyl) thio citronellal against bacteria of importance in foods. In order to observe the antimicrobial activity of 3-(p-chlorophenyl)thio citronellal and to verify that the addition of thiol enhances the bioactivity of citral, through qualitative and quantitative study, we compared the antibacterial activity of citral, (R)-citronellal and 3-(p-chlorophenyl)thio citronellal. Analysis was performed by scanning electron microscopy of cells exposed to the compounds in order to infer the possible mechanism of action and observe the behavior of Gram-positive bacteria (L. monocytogenes) and Gram-negative bacteria (P. fluorescens), and check if there are changes in the target cell when citral was modified. From the results of qualitative tests, all bacteria tested were potentially susceptible to the compounds tested, which have antibacterial action, however, quantitative analysis showed that the Gram-positive bacteria are most susceptible. The kinetic curve action cell death demonstrated that for both L. monocytogenes to as P. fluorescens occurs significantly faster when treated with 3-(p-chlorophenyl)thio citronellal, however, when comparing the time of cell death from Gram-positive and Gram-negative bacteria, L. monocytogenes was more sensitive to the compounds. Furthermore, the minimal inhibitory concentration for the 3-(pchlorophenyl) thio citronellal carries antibacterial activity was 100 fold lower compared to the precursor citral. The scanning electron microscopy allowed to show morphological changes in cells treated with the compounds. Apparently, the addition of the thiol molecule citral does not change its cellular target, however, possibly the cellular target of citral, 3-(p-chlorophenyl)thio citronellal and (R)-citronellal is different in Gram-positive and Gram negative. It was concluded that the addition of thiol enhances the bioactivity of citral against Gram-negative and Gram-positive functionalizing this molecule, making a compound having potent bactericidal activity, low toxicity, which can be used in foods.