Chemical Composition, Antioxidant and Antibacterial Efficiency of Essential Oils from Algerian Juniperus phoenicea L. Against Some Pathogenic Bacteria

Abstract

Essential oils (EOs) are known for their medicinal properties which are used in different domains. The current study was conducted to characterize the chemical composition and evaluate the antioxidant and antibacterial efficiency of EOs from Algerian Juniperus phoenicea L. Leaves and berries of J. phoenicea were collected from five different regions in the northeast of Algeria. EOs were extracted from the various plant samples. The analysis and identification of the components of the leaf-berry combination (Lb) and leaf-only (Lo) EOs were performed using gas chromatography-mass spectrometry (GC-MS). The antibacterial activity of the EOs was tested against seven bacterial strains; two Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and five Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, Acinetobacter baumannii, and Klebsiella pneumoniae). To test the antioxidant property of the EOs, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was employed. Forty-six compounds were identified in the Lb and Lo EOs representing 96.8 to 98.2% and 93.5 to 100%, respectively of the total oil composition. The major monoterpenes compounds were α-pinene with percentage composition of 50 to 85.8% and 42.1 to 83.1% in the Lb and Lo EOs, respectively. The EOs exhibited stronger antibacterial activity against the Gram-positive bacteria compared to the Gram-negative bacteria. Moreover, the Lo EOs showed less significant antioxidant activity in the DPPH radical scavenging assay compared to the Lb EOs for each studied variety. These findings support some of the traditional uses of this plant in food preservation by the Algerian people and also validate its use for protection against infectious diseases.