Elodie Guinoiseau ,Vannina Lorenzi, Anne Luciani, Jean-Michel Bolla and Liliane Berti


Laboratoire de Biochimie et Biologie Moléculaire du vegetal Université de Corse, CNRS 6134 SPE, France

Abstract:

The essential oil (EO) of Cistus ladaniferus was separated into non polar, moderately polar and polar fractions by column chromatography. The EO and its fractions were analyzed by gas chromatography in combination with retention indices [GC-(RI)] and 13C nuclear magnetic resonance (13C NMR) spectroscopy. A disc diffusion and a minimum inhibitory concentration (MIC) assays were used to evaluate their antibacterial activity against the gram negative multi-drug resistant Enterobacter aerogenes EA289 strain. The oxygenated fraction (FO) and, more precisely, the alcohol fraction (FO1') are active on this strain. None of these fractions provoke whole cell lysis (bacteriolysis assay) or outer membrane permeabilization (nitrocefin assay). However, we observed a drastic decrease of intracellular ATP after treatment with each fraction without any release in extracellular compartment. These results suggest that oxygenated compounds, and more precisely alcohols, may act either on ATP synthase or the plasmic membrane polarization. In both case, the decrease of cellular energy may be responsible of outer membrane detachment followed by aggregation of intracellular materials (transmission electron micrographies) leading to absence of cell multiplication (time-kill assays). This hypothesis must be confirmed by further experiments on plasmic membrane depolarization (DisC3-(5)) and intracellular composition (leakage of Na⁺, K⁺ and/or genetic material).