Metabolomic Analysis of the Effect of Lippia origanoides Essential Oil on the Inhibition of Quorum Sensing in Chromobacterium violaceum

Abstract

Bacteria can communicate through quorum sensing, allowing them to develop different survival or virulence traits that lead to increased bacterial resistance against conventional antibiotic therapy. Here, fifteen essential oils (EOs) were investigated for their antimicrobial and anti-quorum-sensing activities using Chromobacterium violaceum CV026 as a model. All EOs were isolated from plant material via hydrodistillation and analyzed using GC/MS. In vitro antimicrobial activity was determined using the microdilution technique. Subinhibitory concentrations were used to determine anti-quorum-sensing activity by inhibition of violacein production. Finally, a possible mechanism of action for most bioactive EOs was determined using a metabolomic approach. Among the EOs evaluated, the EO from Lippia origanoides exhibited antimicrobial and anti-quorum activities at 0.37 and 0.15 mg/mL, respectively. Based on the experimental results, the antibiofilm activity of EO can be attributed to the blockage of tryptophan metabolism in the metabolic pathway of violacein synthesis. The metabolomic analyses made it possible to see effects mainly at the levels of tryptophan metabolism, nucleotide biosynthesis, arginine metabolism and vitamin biosynthesis. This allows us to highlight the EO of L. origanoides as a promising candidate for further studies in the design of antimicrobial compounds against bacterial resistance.

A new essential oil from the native Ecuadorian species Steiractinia sodiroi (Hieron.) S.F. Blake (Asteraceae): chemical and enantioselective analyses

“…About the chemical composition, the only EO described in literature from the genus Steiractinia is the one obtained from S. aspera 14 . The comparison between the major component abundance of the two volatile fractions is represented in Fig.…”

“…On the one hand, two articles were published by Bohlmann et al on the sesquiterpene lactones produced by S. sodiroi itself, including the first description of stereactinolides; whereas a more recent article was published by Gamboa-Carvajal et al about the biological activity of hydro-ethanolic extracts from S. aspera 11 – 13 . On the other hand, only one article has recently been published about a volatile fraction from the genus Steiractinia , citing the chemical composition and biological activities of S. aspera EO 14 . Therefore, the present study constitutes the first investigation about the chemical and enantiomeric composition of an EO from S. sodiroi .…”