Bioprospecção da atividade antibacteriana dos monoterpenos (R)-(+)-citronelal e (S)-(-)citronelal contra cepas de Staphylococcus aureus e Escherichia coli.

Abstract

Terpenes are a group of natural volatile substances of plant origin and present in essential oils, which are the main compounds for therapeutic use, isolated from plants. Citronellal is a monoterpene which is found in racemic mixture form or alone. In addition, studies have reported biological activities such as fungicide and bactericide tested and proven for racemic citronellal. The present study aims to evaluate the antibacterial activity of the monoterpenes (R) - (+) - citronellal and (S) - ( Citronellal against strains of Staphylococcus aureus and Escherichia coli. In order to perform the activity, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were analyzed. The antibacterial chloramphenicol was used as a positive control. For this, the broth microdilution method was used, in a 96-hole plate, Mueller Hinton broth and the monoterpenes under study at the different concentrations were added. The assay was performed in duplicate. Plates were incubated at 37 ° C for 24-48 hours for MIC reading. After reading, aliquots of 20 μL were withdrawn from each well that did not show bacterial growth, and transferred to wells of a new plaque, devoid of any antimicrobial. The inoculated plates were aseptically closed and incubated at 35 ° C, and the MBCs were recorded after 48 h. The (S) - (-) - citronellal monoterpene presented a MIC 50 of 256 μg / mL and CBM 50 of 1024 μg / mL against E. coli strains, whereas (R) - (+) - citronellal presented the MIC 50 and CBM 50 of 512 μg / ml against E. coli strains. For S. aureus strains, both monoterpenes presented a value of 1024 μg / mL for MIC 50. With the results analyzed it is concluded that the (R) - (+) - citronellal and (S) - (-) - citronellal monoterpenes can be considered as promising for the treatment of many diseases caused by bacteria.