Journal of Microbial & Biochemical Technology

Antibacterial efficacy of four structurally related phenylpropenes against Escherichia coli and Staphylococcus epidermidis

Joint Event on 4^th World Congress and Expo on Applied Microbiology & 2^nd International Conference on Food Microbiology

November 29-December 01, 2017 Madrid, Spain

Najjar Amal

Lebanese University, Fanar, Lebanon

Scientific Tracks Abstracts: J Microb Biochem Technol

Abstract:

Phenylpropenes (PPs) are volatile hydrophobic phytochemicals generally characterized by their potent antibacterial activities. The modes of antibacterial actions of these molecules differ from those of conventional antibiotics, which suggests their usage may help overcome antibiotic resistance mechanisms. The efficacy of allylic/propenylic PP isomers (eugenol/isoeugenol and estragole/ anethole) was evaluated by macrodilution methods allowing to determine IC50s, MICs and MBCs against reference strains, Escherichia coli ATCC 25922 and Staphylococcus epidermidis ATCC 14990. Results indicate that all PPs were efficient against both bacteria in low millimolar levels, which makes them considerably less potent than common antibiotics. Allylic/propenylic isomers presented very similar growth inhibition patterns, indicating that the position of the double bond in the propenyl chain has low influence on PPs efficacy against the studied strains. For both strains, eugenol and isoeugenol were two to three times less effective than anethole and estragole, indicating distinctive modes of actions between these two pairs of isomers. Eugenol and isoeugenol would particularly involve their hydroxyl group to elicit antibacterial activity. Lacking a free hydroxyl group, the mode of action of anethole and estragole may be rather related to their higher lipophilic character. Interestingly, gram-negative E. coli, showed to be more susceptible to all PPs than the Gram-positive S. epidermidis strain, probably due to the easier permeation of PPs across the hydrophobic cell envelope structures of E. coli. Using high-dose PPs (low millimolar levels) in vivo may not be an optimal strategy, however the combination of phytochemicals presenting different mechanisms of action may allow reduction of efficient doses. Recent Publications 1. Riham Gharib, Amal Najjar, Lizette Auezova, Catherine Charcosset, Helene Greige-Gerges (2017) 2. Interaction of Selected Phenylpropenes with Dipalmitoylphosphatidylcholine Membrane and Their Relevance to Antibacterial Activity, J Membrane Biol, 250(3):259-271. (doi: 10.1007/s00232-017-9957-y)

Biography :

Najjar Amal has completed her PhD from Mediterranean University – Aix-Marseille II, France, and is currently working as Assistant Professor at the Lebanese University Faculty of Sciences II, Lebanon. She is affiliated with the Bioactive Molecules Research Laboratory at the Lebanese University, and currently working on investigating the antibacterial and antibiofilm activities of plant bioactive compounds, as well as the impact of confinement of these compounds in nanoencapsulation systems on their activities.