Early view

Nacéra TADJINE, Atika BENRIMA, Noureddine BOURAS, Fawzi Rostane MEKLATI

Abstract

The present study evaluated the chemical composition and antibacterial activity of Juniperus communis L. and Pistacia lentiscus L. essential oils (EOs) and their 50:50 mixture against clinically relevant Gram-positive and Gram-negative bacteria. Antibacterial activity was assessed using agar diffusion, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and fractional inhibitory concentration index (FICI) assays, while the chemical profiles were characterized by GC-MS (Gas Chromatography-Mass Spectrometry) and FTIR (Fourier-Transform Infrared Spectroscopy) analyses. Both EOs exhibited antibacterial activity, with Gram-positive bacteria showing greater susceptibility than Gram-negative strains. The MBC/MIC ratios were ≤ 4 for all tested samples, indicating a predominantly bactericidal effect. Among the evaluated formulations, the 50:50 mixture displayed the highest antibacterial activity, particularly against Staphylococcus aureus, with a MIC value of 3.12% (v/v) and a synergistic interaction against S. aureus ATCC 6538 (FICI = 0.49). GC-MS analysis showed that the mixture was rich in monoterpene hydrocarbons (64.2%), followed by sesquiterpenes (19.3%) and oxygenated monoterpenes (8.1%). The major constituents identified were α-pinene, limonene, β-pinene, myrcene, and terpinen-4-ol. FTIR analysis confirmed the terpene-rich nature of the oils and supported the GC-MS results. The enhanced antibacterial activity of the mixture is likely associated with additive and synergistic interactions among its bioactive compounds, leading to increased disruption of bacterial cellular functions. These findings suggest that the combination of J. communis and P. lentiscus EOs represents a promising natural antibacterial agent, particularly against Gram-positive pathogens.

Keywords

Juniperus communis, Pistacia lentiscus, essential oils, antibacterial activity, GC-MS, FTIR

 Download